In Part 2 of our How To Tune series, we’ll be focusing on tuning the wide open throttle portion of your fuel map. You may have also found this article from our continuation of our How To Tune Haltech guides. Either way we’ll be giving you a step by step process to tuning your vehicle on the dyno for wide open throttle operation.
Intended mostly for standalone vehicles, this writeup is also applicable if you are using a Apexi Super AFC NEO, or Greddy Emanage or similar device. It’s important to have a firm grasp on how to dyno tune you vehicle before actually hitting the rollers, so let’s begin.
We also have a How To Tune Closed Loop Operation guide available as well if you are looking information there.
Things you should know
Your vehicle should be running in it’s peak form if you are heading to the dyno. This means your fluids, spark plugs and all your parts are in perfect running condition with no leaks or potential issues. If your vehicle is turbocharged you may want to take this time and tighten or reseal your intercooler piping the day before you are to dyno.
Most chassis dynos are rented by the hour, precious time that you can’t waste reconnecting blown off intercooler piping.
If your car is really running in optimal condition and all the proper safety steps are in place, the dyno is a safe place to tune your car. In fact it’s in a much better place for load testing than you speeding down the road and breaking the law. Making a dyno pull should be no more dangerous for your motor than you stepping on the gas on public freeways.
How to begin
Turbocharged, supercharged or naturally aspirated the process and method of tuning an engine are always the same. Using a simple starting point for your engine and load, start from the engine’s idle to the base rpm or boost level. This gives you a point from which to tune from, you can use rpm for naturally aspirated vehicles, boost in psi for boosted vehicles.
Before you do any of that however, you must make sure your vehicle is not on a cold map. Warm up the vehicle and make sure it stays within the map you want to adjust. Never attempt a dyno pull while your vehicle is cold or not at optimum operating temperature.
In short you’ve got to set a base for your vehicle to start from, meaning if you want 16psi tune your vehicle at 7psi and work your way up. Once you have your base starting point set you have something to build on.
If your tuning management allows for interpolation between cells, meaning replicating cascading values, now is the time to do it. This can be a crude way to give you a nice curve up to redline that is excessively rich and therefore safe. This makes it easy to whittle down the map or raise boost to get the numbers you desire.
Full load tuning should always be approached with extreme caution. Always make sure your fuel settings are way above what would be considered stoich. Improperly lean fuel levels at full load can cause detonation that destroys crankshafts, pistons and rings.
Whenever you are full load tuning, make sure the bars above your last known good tune are increased giving you the safety margin to lean out the fuel mixture.
Things you should bring
If you are bringing special fuel for a specific fuel map, buy this the day of and bring it with you rather than drive on it. Keep your pump gas low enough so that it won’t be such a hassle siphoning the pump gas out of your tank.
At least one full set of spare spark plugs is another thing that you most definitely should bring. You will also need a bag of tools as well as tools to tune your vehicle with.
DYNO TUNING TIPS
- Be Aware – Tuning wide open throttle on the dyno isn’t as daunting as one might initially think. If you follow the steps in our guide learning how to tune your vehicle couldn’t be simpler. But that’s not to say you can’t break something still. If you have a piggyback or standalone computer management system, always be aware that you have the capability to blow up your motor.
- Be Safe – We’ll go ahead and state the obvious here, but you want to err on the side of caution. Start out with your fuel mixture rich and work your way to your target air fuel ratio. If you are turbocharged you will want to start out with low boost to determine a baseline, and work your way up from there.
- Go Slow – Always take your time and don’t let your parts get heat soaked. Remember to allow your motor and any intercooling components of your forced induction system to cool off between pulls. If you don’t your car may become heat soaked, which in turn muddles your tune and your dyno numbers.
- Don’t Change too much at once – Never change more than just a few values, which is a very common mistake. Changing too many values before another dyno pull could cause you to lose a lot more work than you might realize. Big changes will result in widely varying results and air fuel ratios. Change to much at once and you’ll have to start from a much earlier map or version.
- Save often – Save your maps frequently and under different names, if you are using a piggyback record your changes and results, making reverting to a previous tune simple and easy.
WHEN USING A PIGGYBACK
You are going to want to watch several values when tuning with a piggyback, and the first is the basic engine inputs. Using a datalogger fast enough to keep up, you should be monitoring the engine load, and coolant temperatures at all times.
During full load pulls you will want to watch the ignition timing and knock values if the ECU presents these values to you real time. Stating the obvious once more, you ideally do no want knock throughout your dyno pull. If a knock value is not something you can read using the datalogger you have, reference ignition timing instead.
As the vehicle invariably has ignition controls that are knock based, getting a much lower ignition timing value during a pull is a surefire sign of predetonation.
The other value to watch is your wideband 02 sensor, which will present you with the real time air fuel ratio of the exhaust. There’s a target air fuel ratio number you want to reach, depending on your vehicle.
If you are using a piggyback like the Super AFC NEO, there may be additional tuning to do even after you are done with WOT tuning. If your vehicle is based on a MAF ( Mass Air Flow) or MAS (Mass Air Sensor), you may have a problem if you are forced induction.
If your turbocharger or supercharger vents the pressure to atmosphere, this is air that your ECU is assuming still exists in the system. This can create an overly rich condition and excessive backfire as well as spark plug fouling. If your piggyback has deceleration map values, you will need to tune these out if you insist of venting to atmosphere.
Remember to try and keep all the values you are watching as steady as possible. You want to replicate the conditions of your previous pulls in order to exact the best possible fuel map.
WHEN USING A STANDALONE
Standalones will all vary in this arena, but we’ll be assuming you are using a Haltech standalone tuning computer.
Here is a checklist of parameters to check during your process learning how to tune your vehicle for wide open throttle .
1. Fuel Setup – Where you’ll be spending most of your time on the dyno, the full throttle map is most likely based on throttle position. Once you’ve exceeded a certain point, the standalone interpolates values it does not have to provide a smooth full load situation.
2. Full Throttle Map – For certain standalone applications and naturally aspirated cars, you may need to correct your full throttle map before wide open throttle. For some naturally aspirated cars, the manifold pressure can reach close to full load before full throttle is reached. Cases like this will require an decreasing fuel values to compensate for this curve.
3. Ignition Timing Advance – Where you get to adjust the ignition timing should you feel extra adventurous or have an alternative fuel. If you are not comfortable tuning your own vehicle, this is the last table or set of values you should be messing with. Advanced ignition without the proper load control or tuning could cause your pistons to melt before you even know what’s happening.
3. Ignition Timing Curve –
4. Zero Throttle Map – A problem that can lead to a rough idle and performance issues, this map is correct intake manifolds that fluctuate in air flow delivery. In cases where the Manifold Absolute Pressure sensor cannot read the values correctly, a zero throttle map may be needed. This map will give you a solid idle when used with a air bypass valve or idle air controller.
02 Sensors – Your tuning eyes
Most standalone computers will have provisions for narrowband and wideband 02 sensors, be sure to use a good 4 wire 02 sensor if a wideband is not an option.
In yet another Captain Obvious moment, you are only as good as your sensors are as a tuner.
Have any questions or need some clarification? please leave us a comment below!