TherE is more to a tune than a pretty dyno sheet

Many of us have seen the Facebook posts of tune MAPs and heard the stories of horror tunes, but what makes a good tune or a bad tune? Many common tuning practices are incorrect and result in sub standard results. A good tune is much more than a dyno sheet.

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Emissions, Tuning and registrATION

The impact the EPA crack down has had on tuning is to reduce the ability of US based tuning software to modify and delete emission controls. So, if the EPA continues to crack down on US tuning software companies are they just pushing the industry underground? I agree that something needs to be done about emissions and there are still many performance modifications that can be made while remaining emission compliant. There are multiple non-US based tuning software suppliers that are not under EPA directives so is the EPA just hurting US companies? Is there an opportunity to legally cater for modified vehicles emissions in Australia?   

 The next step for the EPA is to tackle the performance industry shop by shop, it has started but will not be nearly as easy as targeting the large US based software suppliers. What does this mean for Australia?  My guess is a move away from US based tuning platforms like HP Tuners, Cobb, SCT and a trend towards European and Russian software that is not subject to the same EPA limitations.  The sanctions on Russia seemed to slow down the Russian software suppliers for a week or two, now all this is supported from servers outside Russia with barely a hiccup. There are still hundreds of tune file suppliers more than happy to delete and turn off whatever emission control device you wish, and while large fines exist for emission tampering in Australia for both individuals and businesses it seems to be infrequent at best and RWC testers have no ability to test for emission compliance beyond visual inspections. How do you enforce a penalty without reasonably priced infrastructure to test for emissions? It seems unfair to be fined for all but the most blatant of offences as there is no testing facilities in many states including Victoria for actual emissions. Picture a breathalyzer for the exhaust.  

It is my hope that we may have a more inclusive approach to modified vehicles and emissions than CARB in the US.  The industry should be able to survive but I do think there is a shakeup required.  In Victoria what is needed is an emissions testing station, multiple, but let’s start with one.  ABMARC have failed to provide a solution due to insufficient profit, and that was at a cost that the industry could not support.  When compared to NSW that has a free testing station Victoria is lagging.  The Victorian and Federal Government has seen fit to invest into the AIC (Auto Innovation Centre) but has neglected one of the most necessary aspects of the aftermarket, emissions compliance.  Both State and Federal governments claim to be supporting the aftermarket, the reality is most modifications made to vehicles include a performance enhancing aspect but there is no testing facility to assess these modifications either for emissions or quality. 

If proper testing was available then an option exists to offer modified vehicle registration where polluters can pay higher registration for carbon offsets.  The current system of Police removing cars from the road for RWC testing does not address the issue satisfactorily.  Police are not properly trained in vehicle modifications or emissions and RWC testers are unable to test emissions anyway.  Modifying and returning to stock of cars for the sake of passing a RWC inspection is ridiculous but is happening frequently and does not deter people from making illegal modifications anyway.

Nothing comes for free, if you can afford to modify your car then you can afford some additional costs to do so as environmentally as possible but then should be able to enjoy the modifications without fear of fines and reprisals.  With the correct equipment it would be easy enough to estimate the additional carbon output and cost of offsetting this.  This would also provide opportunities to improve the quality of aftermarket tuning with facilities that can test for all the harmful gasses, modified vehicle emissions can often be minimized which would reduce the carbon offset cost for the consumer and encourage more efficient tuning, discounts could be given where older vehicles have reduced emissions due to the fitment of newer cleaner engines or fuel injection is retrofitted. No one wants to think of additional running costs at the moment but if everyone pays their own small share relative to the level of additional pollution they make then maybe a compromise can be made. Certainly the current Russian Roulette system of modify, anxiety, return to stock could be eliminated, at least from an emission perspective, these additional funds could be funneled into emissions reduction projects testing facilities and education on tuning for emissions in modified vehicles.

New Tech, new Customers, the performance workshop, what’s changed and is it viable?

Performance upgrades are nearly as old as cars themselves dating back over 100 years.  But how times have changed.  The last decade has seen a huge change in the performance industry, for better or worse, it is without doubt though the performance workshops of today have a difficult task keeping up with technology, the volume of makes and models and customer expectations.   The advent of the internet has bought with it many changes, forums, Facebook, eBay, Instagram, online shopping and drop shipping.  On face value these things may seem to be innocuous and even beneficial to the customer, the customer can price check and purchase from numerous places and has access to information from an unlimited number of sources.  This is not all great news for the workshop and maybe not all so rosy for the customer when you have a deeper dig into it.

 Automotive mechanical repair labour rates have been undervalued for decades, customers may disagree but when compared to other trades such as electricians and plumbers this is the case. Most electricians and plumbers have lower overheads, require less factory space and fewer tools, many operate from a commercial vehicle.  A typical workshop will have multiple hoists, a range of hand and power tools also specialised diagnostic and vehicle tools.  A performance workshop will have a chassis or hub dynamometer and fabrication tools costing hundreds of thousands of dollars in addition. Many customers seem oblivious to the costs of running a performance mechanical business, and while dealerships are charging $150+ per hour the mechanics on the tools are lucky to get $40 per hour.

Mechanical workshops supplement the labour with a markup on parts, margins are usually sufficient such that the hourly labour rates can be kept lower.  In the performance industry the availability of parts online has reduced the margin and has eaten into the profits of the Performance workshop. The viability of the performance workshops with margins dropping lower than 10% is severely compromised.  Many Performance workshops no longer supply parts as there is barely sufficient margin to cover the bookkeeping costs without any consideration for warranty, these workshops have the customer supply parts hoping the customer will accept responsibility for faults and failure. The reality is it is difficult for the workshop to isolate itself from part-based failures where they agree to fit the part, by fitting a customer supplied part as the professional installer the workshop assumes liability and responsibility that the part is suitable for the job.   Performance work tends to have the highest risk for the lowest financial reward, and although the work can be fun and exciting many customers are of the opinion that the workshops should be offering increased discounts for the privilege of working on their vehicle and unfortunately many workshops, both performance and regular are fearful of missing out on work and take on more work at lower margins than they should. In the long term it is unsustainable, and the result is workshops open late into the evenings trying to keep ahead of the bills and the workload generated by taking on too much or to satisfy ever-increasing customer demands.

Information being readily available to the consumer these days in so many forms and sources, yet it often lacks the substance or knowledge available from a performance workshop with many years of experience.  Consumers look to Forums and social media groups where there are a multitude of different individual experiences, this lacks the compound knowledge that comes from multiple learned experiences from trying many different things that can be achieved in a workshop.  The huge amount of advice available can be confusing and when researching customers tend to be biased and place greater emphasis on the advice that suits their needs or budget as to what is the most accurate or appropriate.

The individual experiences of many are less valuable than the many experiences of one. Take the example of camshafts where 5 individuals upgrade their camshafts in 5 separate vehicles that were previously stock, they all perform better than stock but none of the 5 individuals have the experience of all 5 camshafts, that can only be found in a quality performance workshop, so how does any one of the 5 individuals honestly evaluate their choice in comparison to the other 4 options?, they can’t, they don’t have the experience.  Each individual will tend to believe they have made the best choice based on the information they have, rarely will you find someone on a forum willing to confess they did not make the best choice even if they felt it to be true.

Social platforms like YouTube have made it possible for consumers to educate themselves on the fitment of aftermarket components, the compressed format has meant many difficult and time consuming tasks that require experience and knowledge are trivialised in both time and complexity in such a way that consumers think a large complex task such as engine rebuild or restoration occurs over a much reduced time to what it does as they watch YouTube videos cut down to 20-30 minutes. This can give the customer an unrealistic idea of the cost and complexity.  This has also created a situation with older vehicles that have several new performance parts fitted with general wear and other mechanical issues, customers are expecting the same results as may have been achieved on YouTube or other social platforms.  This often unfairly becomes the problem of the tuner who is expected to tune some new parts in a vehicle with an aging engine and aging sensors.  Consumers who have committed their budget to a handful of online parts now have the situation when confronted by the tune shop that they need fuel pumps, filters and 02 sensors, and that’s all if they are lucky.

There has been a move towards social influencers who are paid to offer product feedback, this has meant there is less truly objective reporting on products, so much so that social influencers leverage businesses and product manufacturers for discounts and freebies in exchange for favourable feedback.  This has existed in previous forms in the past as this trend began in the 90’s with product manufacturing groups taking over automotive print media to advertise and favourably report on their own products.  These days it is everywhere, finding the truth has become nearly impossible.

Social media has been reduced to a series of short “reels” that either highlight successes or failures but never show the journey.  The highlight of a stock engine car boosted to run a 9 second pass doesn’t show the effort or failures to get there, consumers have a detachment from the time, effort and risks associated with performance upgrades and having not experienced the journey believe such feats are easy and without risk. 

Several performance workshops I know of are shifting to smaller workshops with reduced staff and a more discerning select customer base realising there is no value in chasing the migratory social media crowd that expect the impossible on a shoestring budget or want to leverage perceived celebrity for discounts, the loyal and respectful clients are getting the benefit of the wisdom of years in the performance industry.  Many are closing or moving back to more traditional more profitable auto repairs.  Newer and younger shops continuously pop up and compete for the same Insta fame market, they continue to undercut each other, functioning off impossibly low margins working increasingly long hours to keep ahead and have no financial or time buffer for when the shit hits the fan, it is an impossible scenario that can only end in poorly for someone, either a disappointed customers or burnt-out workshop staff.  Pandering to customers who think they are doing the workshop a favour by allowing them to work on their car.

Consumers in their 20s and 30s new to the performance aftermarket grew up in the back seat of and leant to drive in a different generation of vehicle to those in their 40s and 50s. Old vehicles were less reliable, carburettors and manual chokes, cars would stall, overheat and break down, people came to expect it, especially in the aftermarket.   New vehicle technology that makes a modern car the smooth reliable powerful thing that it is does not always transfer to the aftermarket.  Today the expectation is that every car will be able to make another 200-300-400 hp and beyond, this is despite the higher starting point, and to do so with the same reliability and longevity.  Consumers that have grown up with late EFI powerful cars are not educated to except the compromises of a heavily modified car, they do not understand how manufacturers build and test cars extensively for cost vs reliability nor do they realize the thousands of development hours the manufacturer puts into delivering these vehicles.  The technology and parts do amazing things however the level of complexity to correctly modify and tune these late model vehicles is ever evolving at a rate exceeding the knowledge and budget of many consumers and workshops.  OE’s put teams of people on calibrating a late model over many months yet consumers expect the aftermarket tuner to perform the same feat in a matter of hours often with a collection of parts in a worn-out vehicle.

A customer sees a social media post of a turbo LS that makes 1000hp on stock internals, so they believe that is something they can achieve, they ask on a social network and get 100 opinions on how to do this, here they can choose the answer that best suits them as opposed to the most well researched or tested, typically the answer that suits their budget and desires is the one selected.  They buy a bunch of parts and try themselves or bounce from shop to shop spending 3 times what they thought, blaming shop after shop for not being able to achieve what they saw on social media or for having component failures, maybe eventually they get there without hand grenading a few engines and transmissions but the engine they now have has worn ring lands and the bores are deformed from excessive cylinder pressures, the engine uses oil and pushes water past the head gaskets and they now have to build the motor they should have built in the first place that was fit for the purpose. 

The path currently travelled seems a difficult one, with neither the customer nor workshops being happy, customers bullying workshops using social media, workshops expected to work for the privilege, I am unsure where this goes from here, but I see no winners.

What is to come of vehicle tuning?

 The world of aftermarket tuning may slowly be being turned on its head, over the last 10 years the EPA in the US has been looking to clean up dirty emissions from the aftermarket industry, where this is going and what will we be able to tune moving forward remains to be seen.

The Clean air act is a 50-year-old law Federal law that authorizes the EPA to establish air quality standards to protect public health and welfare and to regulate the emission of hazardous air pollutants. 

For many years the EPA has set its sights on large corporations responsible for breaching air and water quality regulations, one such well know case was diesel gate where in 2015 the EPA issued a violation notice to the Volkswagen group who had been found to be designing their vehicles to pass an emission test as opposed to actually passing emissions in normal use, the software on the car could identify when the test procedure was being performed and would modify the vehicle tune to be compliant for the test.  Since this other vehicle manufacturers have been found to be using the same techniques, Mercedes Daimler, Fiat Chrysler, Hyundai Kia and others.

 More recently the EPA has looked towards the aftermarket, rolling coal tunes, DPF and Catalytic converter deletes seen as cheap performance upgrades have meant as a result the aftermarket has caught the attention of the EPA, and its no surprise really when one DPF deleted rolling coal diesel can produce 60 times the emissions of a stock vehicle.  In many respects the industry and the customers bought this on themselves.  Looking cool on YouTube smoking out pedestrians may look funny but was never going to go unchecked.

There is now an extensive list of aftermarket companies, initially larger but now also small family businesses, that have felt the rath of the EPA. Fines exceeding $1000 per vehicle offence for component sales that defeat emissions, criminal inditements for conspiracy to “Intentionally Violate the Clean Air Act” with $250 000 fines and jail time, those modifying vehicles need to have a serious think about whether it’s worth it and what modifications should be done.  A quick survey of the EPA site soon reveals the fines ranging from the tens of thousands to millions for selling devices allowing the modification or removal of emission devices to tuning with readily available aftermarket tuning software.

Most recently to fall victim, Cobb (Green speed,) have a forced software update to all their tuning tools with significantly reduced map access to areas that are deemed to impact emissions having received 88 CARB Executive orders.   Other Tuning software companies are scrambling, trying to satisfy the EPA and not lose the consumer, already HP Tuners, EFI Live, Diablosport, SCT/Bullydog, UpRev, APR and numerous others have already been fined, approached, or warned by the EPA to clean up their act with fines and forced improvement plans into the millions of dollars. Green Speed Update (April 2022) - COBB Tuning

 Not even the little guy is safe, having a name for yourself as a good tuner in the US these days may be like having a target on your back, Evans Tuning a smaller well respected Pennsylvania tuner recently found to be in breach of the Clean air act on 103 occasions was liable for tens and maybe hundreds of thousands in fines although the Civil fine was reduced to $4223 due to an inability to pay the full amount Evans has also agreed to cease any activity or sales of parts that can impact emissions, having to demonstrate all future works do not impact the operation of the OBD systems.  A breach of this order would likely result in jail time and further fines. The list below from the Consent agreement shows nothing out of the ordinary for the average tune shop to be doing.

 Here in Australia, we are not immune to the impacts of this, most workshops offering tuning will be using one or more of the OE tuning products available from the US.  

You can forget about code delete for Catalytic and DPF Removal and due to less effective aftermarket Catalytic converters, at least from the major software brands for now, there will no doubt be a smaller underground tuning scene using tuning tools from outside the US, but that becomes limiting as there will be no US dealers for these products, and it is likely only a matter of time before the EPA and the long arm of the law will continue to track down and punish individuals tuning having made the larger software companies compliant.  A similar trend is likely to be seen in Europe, many countries are similarly cracking down, Japan already has heavy fines and makes the modification of new vehicles very difficult.

It is inevitable that the large brand software companies will comply in the US, whether some will run the gauntlet in other countries in an attempt to maintain market share remains to be seen, if they can Geofence the software and hardware for regions like the UAE that don’t care, maybe, but there is always the risk Australia and European countries follow suit and like the US and start to hand out hefty fines and jail terms. It is unlikely in Australia, which is ridiculously unregulated in automotive, we have not even managed to license mechanics and brake pads can be made of cheese. To think the Federal or State governments could regulate tuning in the near future is very unlikely although in my opinion mechanics and tuners should have a minimum standard of training and be regulated as currently the market is based on internet celebrity not competence.  Many modifications have been illegal in Australia since the inception of emission standards and ADR’s here in 1969.  Despite the already high fines for emission in tampering in Australia, Court imposed fines of up to $22000 for individuals and $44000 for companies, it has been no deterrent as fines seem to be very few and far between. 

There will undoubtably be a rise in hacked, opensource and binary editing software, much of which has come from Russia (problem) in the past, but there is no shortage of groups, forums and open-source information that will continue to find the software bytes to change for emission defeats.  The cost of tuning may go up if two pieces of software are used, one for code deletion and a second for tuning. The legitimate software companies being the biggest losers, from which with reduced revenue will come reduced development, already many tuners have “work around” solutions for reducing licensing costs which may continue to damage an already uncertain future.

Expect to lose Pops and crackles from the large software suppliers, or if you do have it with stock Catalytic converters expect to be replacing OE catalytic converters that will fail rate due to the excessive temperatures associated with Pops and crackles. High flow catalytic converters will no longer be able to be used without an annoying engine light, tuners that lean out Catalyst enrichment for more power will cause the premature failure of OE Catalytic converters resulting in high replacement costs, typically in the thousands of dollars for OE catalytic converters. If your car is tuned already with these codes off that shouldn’t change, it is unlikely any software supplier will modify tune files on a personal computer to restore factory code settings on the chance the vehicle may be retuned, but it is certainly possible…  Bad tuning will no longer be able to be masked with the blanket deletion of codes which will result in greater consumer awareness as those engine lights indicate faults previously hidden.

Having been in the performance aftermarket industry for nearly 30 years modifying and tuning cars I find I am often torn between what is legal and where I sit morally.  I greatly enjoy the challenge of making a modified car run well, and in doing so reducing the emissions as much as possible from the modified car, there is no need to have poorly tuned cars running around, why tuners remove oxygen sensors and don’t tune for maximum efficiency is lost on me, an efficient car is powerful and economical.  The industry is large, it would be a huge loss to an already crippled industry since the loss of vehicle manufacturing if it was to be shut down.  Just because the aftermarket here is unregulated and basically a free for all does not mean as tuners, we need not be socially irresponsible. If we do better as an industry and educate the consumers rather than bending to every request there is a greater likelihood the industry can continue to survive, with the advent of electric cars and much tighter OE vehicle security preventing ECU access we are already on borrowed time.

2020 Clean Air Act Vehicle and Engine Enforcement Case Resolutions | US EPA

MAF or MAF less?

What is the best option for tuning a GM vehicle?

This is a common and somewhat misunderstood question regarding what will offer the customer the best overall performance.  The most appropriate answer depends on the use of the vehicle and the design of the intake.

For early LS1 vehicles, the P01 ECU had a small and less powerful processor, that was fine as it didn’t have a lot to do, like your laptop or home PC the speed of the ecu required depends on the number and complexity of tasks it has perform.  In addition to this the MAF used was relatively small in internal diameter and offered a restriction with only modest modifications, the removal of the MAF did not inhibit the performance of the ECU and did reduce the amount of restriction in the intake offered by the MAF sensor itself.

The standard early P01 ecu will run without the MAF without further changes but does loose some of its functionality, with the MAF removed the ECU logs a fault and defaults to the low octane timing table reducing the ability to modify the spark timing based on fuel quality and knock, without tuning this would result in a loss of performance.  Fortunately, the aftermarket saw to this with modified operating systems that restore the full functionality of adaptive timing system.

The later ECUs become a different story, the calibration data alone on an E38 or E67 ecu is 10 times larger than the early P01.  This means more and larger tuning Maps. The number of tasks has greatly increased with CAN messaging to the various vehicle control modules, this provides additional stress on the processor.   CAN messages are prioritised by the ECU and those deemed less important can drop out when the processor is stressed.  In addition, tighter tuning control for emissions and performance is added, the rpm pickup has twice the number of teeth and the camshaft sensor 4 times the number so the ECU is aware precisely the location of the rotating assembly at any time, this allows for more precise spark timing, misfire detection, knock detection and injection timing. 

All early P01 through to current GM Delphi ECUs operate on a similar principle where to relieve the processor from demanding Speed density calculation at high RPM the ECU switches the airflow it uses to solely the MAF, up to this point it uses a fancy blend of MAF and Speed density based on utilising the strengths of both methods.  The MAF requires no calculation as it is a sensor that measures Air flow, speed density is a calculation requiring manifold pressure, inlet air temperature and engine speed.  Within the P01, P59 and E40 ECU is a speed density efficiency Table, for the next generation a series of maps with data that form a speed density equation exist, the most current ECUs now use a Neural Network which still forms a more complex speed density output.  This calculation takes processor time, GM switch off this calculation at high speed, typically above 4000 rpm.  This frees up the processor for other tasks, importantly timing and knock control.

At lower engine speeds the ECU calculates the airflow and measure the airflow, it does this and determines the dynamic airflow, this is the most accurate airflow value as it uses the strengths of both methods.  The MAF is accurate at high flow but less at low flow, it also sits out the front of the intake so suffers from a small lag time and therefore cannot measure transient(changing) airflow as quickly. The MAF also needs a straight section of flow to be accurate or the air can buffet around the sensor element causing faulty readings. The speed density is calculated very quickly at low air speeds, it is therefore good for transient airflow changes and at low flow around idle and when large camshafts can disrupt the airflow due to reversion.

What this all means is that the choice to retrain the MAF depends on the application.  The MAF card used in LSA and later vehicles has the benefit of being able to be scaled to larger intakes, in most NA street car applications the stock MAF offers no restriction and causes no loss of performance.  Retaining the MAF with a head and cam package or boosted engines up to 800 HP is usually the best choice as the MAF pipe can be enlarged so no restriction is present and the ECU can utilise both the MAF and Speed density to produce the best dynamic airflow.  If the vehicle is correctly tuned for the two airflows, then it will be able to idle and drive at low speed better and will have more time for optimal timing processing above 4000rpm. In positive displacement superchargers that have very short intakes that are very large and very sensitive to restriction often a MAF cannot be used, not because of the potential of restriction but due to the inability to accurately measure the turbulent air in the short intake. 

In conclusion for early LS1 P01 ecu vehicles, the MAF is restrictive and offers little advantage. For later vehicles with E38, E67 and newer ECU’s retaining the MAF when correctly tuned results in better drive ability, faster ECU timing processing at high engine speeds for increased performance and lower stable idle speeds.  For all but the most high-power vehicles where the fitment of a MAF is not possible it is best to be run.

Do wire in chip tuners work on late model petrol cars?

There are a number of wire in and plug in interceptor style tuning devices on the market designed to intercept the wiring from the sensors to the ecu so as to trick the ecu, predominantly into changing the fuelling or timing. 

The way this works is to modify the voltages or pulses from the sensors into the ECU in such a way that the ecu is manipulated by being fed a modified signal or voltage.  If for example if the MAF (Mass Air Flow) sensor is intercepted and the output from the MAF is lowered via the interceptor to below what it actually is then the ecu will register less airflow, this in turn will cause it typically to remove fuel and add timing as this is what happens at lower airflow.  The chip will intercept many sensors, in part to be able to adjust them and to satisfy the ECU’s internal checking.  For decades ECU’s have had codes that warn of a fault, as technology improves, and the ECU becomes more sophisticated these internal checks have become increasingly more accurate and reliant on sophisticated modelling within the ECU.  In early electronic ECU’s a sensor would indicate a fault code if the sensor was out of range, if we take the example of a throttle position sensor that has an expected range of 0.3 to 4.6 volts if the voltage falls outside this range, then a fault code will log.  As technology has improved there has become an increasing amount of cross checking.  A current model ECU will check the TPS in multiple ways.  A given TPS voltage represents a throttle angle.  Within the ECU will be a predicted airflow model based on the throttle area at any given angle, the ECU can predict the airflow through the throttle based on its model and compare this the actual airflow measurement from the MAF or speed density calculation.  The throttle model can also predict the manifold pressure at a given amount of throttle opening area, this also is cross checked against the measured air pressure.  This advance system checking occurs for all the vehicle sensors, this needs to be considered if attempting to fit an interceptor style tuning device as it is likely to impact these checks and present fault codes.  

Let’s say for example we have wired in the TPS, MAF and MAP sensors to our interceptor chip and with careful adjustment have been able to prevent fault codes, by lowering the TPS, MAF and MAP outputs we have tricked the ECU into incorrectly calculating the airflow lower, the ecu is now getting enough data that correlates between the sensors to not fault code, however this now has the ECU calculating a different, lower, airflow.  The primary job of an ECU is to accurately calculate airflow so it can as accurately as possible estimate the mass of air in any one cylinder so as to calculate the fuel quantity requirement and output torque.  What has been achieved on the surface may look fine as this was the intention, to lean the vehicle out and to add timing by reducing the airflow calculation, what may not be considered is the impact to other vehicle systems.  By reducing the airflow calculation below what it is in reality the ECU calculates a lower torque output, in doing so other components that rely on the torque output will be given false and lower torque data.  In the case of automatic transmission vehicles this can result in reduced line pressure, early shifting and reduced shift torque reduction.  Over time this can potentially damage the transmission.  Late model transmissions are adaptive and measure internal slippage they have the capacity to adjust the shift pressure, within limits, the transmission may appear to be fine but may deteriorate over time. Another system reliant on the engine output torque calculation is the traction and stability control, if the torque output is calculated low due to the modifications it may also impact the ability for the Traction Control and Stability control to work as effectively.

Ignition timing and fuel quality have a large impact on the output of most late model performance Petrol engines.  In order to maintain the optimal performance without damaging the engine as fuel quality varies all late model ECU’s use a means to detect Knock.  Knock is the uncontrolled spontaneous combustion of fuel under pressure that causes excessive spikes in cylinder pressure that can damage and destroy the engine.  Lower quality, lower octane fuel is more prone to Knock, and the ignition timing needs to be retarded so the combustion process starts later, this results in less power and economy.  There is an ignition timing for any load and RPM that will yield the highest engine torque output, modern ECU’s attempt to get as close to this point without damaging knock occurring.  This point is called MBT, there are multiple interpretations of this, Mean Best Timing, Maximum Brake Torque, but it is the optimal ignition timing for a given load and RPM.  This is important for several reasons, as part of the torque calculation the ECU compares the current ignition timing and compares it to the MBT timing table. The further the actual ignition is away from the MBT timing the lower the engine torque will be, the torque output calculation will be modified relative to the distance (how far the actual timing is form the MBT table) to MBT spark timing. There is a similar torque output scaling relative to the mixture ratio which further contributes to the torque error output if the ECU is not achieving the desired mixture that it requests relative to the internal tables.

GM High and Low octane tables with a tuned aftermarket camshaft.

Example of Torque calculation lowered and knock learn to low octane timing due to knock in a supercharged LS 427

An interceptor chip is wired into the crank and camshaft sensors of the engine, these produce a pattern pulse that is used by the ECU to constantly know the location of the crankshaft and camshaft, so it knows where in the combustion cycle each cylinder is. The crank and camshaft sensors are in a fixed location and form the reference point from which all ignition and injection timing occur.  The interceptor chip electronically movers this reference point by shifting the phase of the pattern generated, by adjusting the point of reference back or forward the point of ignition and injection will move similarly.  It is in this way timing advance can be added to make more power, in theory.  The reality is more complex, as mentioned prior the ECU is using knock sensors to monitor knock activity, these sensors will remove timing if knock is present.  In late model ECU’s there is a method to adapt the spark to suit the current fuel quality or octane level.  This is often achieved with multiple sets of ignition tables that are set for high and low octane, increased levels of knock move the source of the ignition timing from the higher spark tables to the lower spark tables.  Due to the high compression ratios or boost used in modern cars the vehicle rarely achieves the highest spark table all the time, they tend to float between.  It is due to this that interceptor chips can create large issues. In tuning the interceptor chip the tuner will try to add timing, as he does this the engine tends to detect knock due to the additional ignition advance, this is unlikely to be audible as the sensors are much more sensitive to low levels of knock than we can hear unaided.  As the knock sensor detects knock the timing will move more from the high octane to low octane ignition maps, resulting in a return to the previous timing, the temporary gain in power that may have occurred is now gone so the tuner adds more timing again resulting in knock further pushing the ignition source to the lower spark map.  This process may be repeated until the ignition timing has hit its point of maximum retard or be on the low octane spark map fully.  At this point the tuner may be able to force more timing into the engine as the ECU has run out of ability to reduce timing due to knock.  Two things have happened here.  The engine is running much more timing than the ECU is commanding because the point of reference has been moved, and the torque calculation has been altered in error. If the Interceptor chip is adding 10 degrees by moving the reference and the maximum timing the ECU can remove is 8 degrees then the engine may be running 2 degrees more timing as measured with a timing light however this is not what the ECU is outputting, the ECU does not know that its point of reference has been moved.  The ECU is only able to see the retarded timing it is outputting and calculating the torque based on the 8 degrees reduced timing, in fact the engine is producing more torque as it is operating with 2 degrees more timing, this will further impact the operation of any systems reliant on the torque output calculation that is now potentially a very long way off and lower.  The tuner will often add timing until knock is audible and stop just prior.  This may sound good as now we have managed to make more power, but what happens the next time you fill up at a different service station or you are in the country and only 95 not 98 octane is available?  The engine will knock and have no more ability to remove timing due to knock as it has been forced back to the minimum learned spark value.  Knock or detonation and engine damage or potential failure can result.  Your sophisticated knock-controlled system designed to produce optimum safe power for varying fuel qualities has been reduced to a 1970’s distributor.

Beware the interceptor chip to tune your late model car, there may be unintended negative and expensive side effects for the small apparent gains achieved.

Injectors, how big is too big?

There appears to be some confusion amongst consumers as to the benefits and time to fit larger injectors. Many times, I hear of customers dictating to the tuner that larger injectors are needed or supplies larger injectors to be fitted for tuning seemingly under the impression a larger injector will make more power.  It poses the question. How big an injector should you fit? 

What are the ultimate plans for your engine? No one wants to buy things twice, although those of us in the industry see that often.  This is the time to be realistic, buy once and save. If you have a HP goal in mind, first make sure it is achievable in your budget, a finished 600hp engine in your car is a lot more fun than an unfinished 1000hp engine on a stand.  Be aware of the fuel you are going to run, E85 requires roughly 30% more fuel flow than Petrol under the same engine conditions.

What determines how much power an engine makes?  The main factor is airflow, the more airflow the greater the Horsepower. Fuel should be delivered into the engine in a controlled fashion relative to the air flow, the fuel flow required is a ratio of the air flow. The maximum fuel required is a ratio of the maximum airflow achieved.  The metered air fuel ratio can vary depending on the application typically from 11.7 to 14.7 to 1 for Petrol, this is the equivalent of Lambda .79 to 1.  If we take the example of 14.7:1 or Lambda 1, this means for every 1 gram of fuel there is 14.7 grams of air, at the richer end of the scale at 11.7:1 or Lambda 0.79 there is only 11.7 grams of air for every gram of fuel.

There are multiple calculators online that help with converting fuel flow to Horsepower, these should be used as they provide a good guide as to the correct injector choice based on the Horsepower your engine can make.  These calculators use proven theory and formula to estimate an engines airflow primarily based on its size, the maximum RPM and induction pressure, is it boosted and by how much. The larger the engine, the harder it revs and the more boost it has the more fuel it will require.  From the airflow a fuel flow can be calculated, from the maximum fuel flow the correct injector can be sized based on the number of cylinders (injectors). 

If you have a stock engine that is not going to rev substantially higher there will be no need for larger injectors, in most cases where a high flow exhaust and intake is fitted with high flow catalytic converters the tuner will tune the car leaner than stock as this will make more power, the manufacturer tunes richer so as to not damage the catalytic converter and other components such as 02 sensors.  The aftermarket performance tune rarely takes this into consideration which may or may not cause an issue depending on the use if the vehicle the exhaust heat generated adn the length of time the heat is generated. It is not uncommon to have less injector duty (peak open time), on a tuned car than a factory tune as the mixtures under full load will be considerably leaner.  Larger injectors at this point will be of no advantage but may in fact cause issues with idle and economy. 

An injector has a range that it can operate in, there is a minimum pulse width (open time) the injector can achieve below which the fuel delivery becomes to unstable and inconsistent.  If too large an injector is fitted the car may run overly rich on overrun and idle where the fuel required is below the minimum Pulse width of the injector, this may mean the idle speeds need to be raised unnecessarily just to use the fuel delivered and fuel economy will suffer, in addition at low Pulse widths the injector may not spray effectively, poor atomization can result in rougher idle due to poor combustion.

An injector is too small when the peak duty cycle (on time) exceeds approximately 85%, fuel injectors are not made to be permanently on. 

Choose the injector that suits your build, don’t waste money on parts you don’t need and don’t buy 1000 hp worth of injector for your 600 hp build as ultimately the best injector is the smallest that will do the job while remaining under under 85% peak duty cycle.