General Tuning Preparation Checklist
I see a lot of these cars come in completely unprepared for tuning. It is usually very simple things that the builder or owner could have fixed by taking just a little extra care. Hopefully this guide can help you to be better prepared for your tune appointment.
- Intake and exhaust system should be free of leaks. This is very important and one of the most common issues I see when a car comes in for tuning. If the car has any leaks in the intake manifold after the throttle body it will be nearly impossible for the idle to be tuned properly. In addition to that, if your vehicle uses a MAF (mass air flow) sensor the fuel trims will be way off and the result will be an overly rich condition.
Exhaust leaks will also cause major issues for the calibration process. If there are leaks anywhere between the engine and the oxygen sensor(s) they will not read properly. This will wreak havoc on the closed loop fueling because it creates a false lean condition and the ECU will add fuel creating an overly rich condition. In addition to this, if there are exhaust leaks the vehicle cannot be tuned because AFR readings will be inaccurate. To prevent these types of issues always use high quality exhaust gaskets. In many cases the oem exhaust manifold gaskets are already a nice multilayer steel style of gasket and are nicer than the cheap foil types that come with aftermarket headers/exhaust manifolds. A lot of header kits will come with gaskets. Don’t bother using them as most are the cheap graphite or foil type that doesn’t last long. OEM gaskets are usually cheap and will save you a lot of time.
- Check for fluid leaks and repair them if there are any present. This one is simple. You wouldn’t race your car with a leaking engine, transmission or rear end. Don’t bring it in for tuning this way.
- Fuel System: If the vehicle is equipped with an external fuel filter make sure that it has been replaced recently. In addition, a lot of the cars that people build at this point are starting to get very old and I see a lot of poorly performing fuel pumps even on bolt on cars. If you are considering modifying an older car (20ish years old or more) it’s a good idea to just go ahead and upgrade/replace the fuel pump and the wiring that powers it. If you are unsure of the size of fuel pump that you will need to suit your power goals just ask.
- Ignition system: If they have not been replaced recently install new spark plugs of the proper heat range and at the proper gap. Plug wires are also an area of concern on V8’s with aftermarket manifolds/headers. Some header kits have very poor clearance between the exhaust runners and the wires can touch and/or burn the stock wires or boots. There are many different options for aftermarket wires with angled boots and/or heat shielding. The point here is that the wires cannot touch the exhaust runners. They will burn and cause misfires.
Upgraded Camshaft Installs
If you have installed an aftermarket cam or camshafts in your engine please check and double check that everything is aligned properly. If the cam(s) is installed improperly the car will not be able to be tuned. The engine could also be damaged before you even make it in for tuning.
Nitrous gets a bad rap sometimes. Mostly because of improper use. It really can be just as reliable as any other power adder as long as it is installed and tuned properly.
- In addition to your basic nitrous kit there are some essential extra components you will need.
- Nitrous bottle pressure gauge: It is very important to monitor bottle pressure. The car should always be run at the pressure that the system was tuned to or else it could run too rich or too lean.
- Bottle heater: Used to regulate bottle pressure
- Window switch and WOT switch or progressive controller: For both safety and consistency its best to take nitrous activation out of the driver’s hands. At minimum the vehicle should be equipped with a WOT switch in order to prevent the nitrous from being activated while the throttle is closed. For drag racers a progressive controller will be a worthwhile addition. The adjustability for changing track conditions can be very useful.
- Nitrous purge kit: This is slightly optional, but for consistency at the track its good to be able to clear the line.
- Ignition timing retard controller or 2 separate tunes for NA and nitrous: For customers that are running a stock ecu you will need some way of pulling timing when the nitrous is activated. Some factory ecu’s have ways of controlling this but most don’t. In those cases I can just pull the timing out of the tune, but it will make the car a lot slower when nitrous is not being used.
- Colder spark plugs. Heat range will vary based on how much nitrous
- Plumbing and install tips
- Nitrous systems use a lot of AN and pipe thread style fittings. It is not recommended to use Teflon tape on these as it can sometimes get into the solenoids and clog them. This could cause major problems with either fuel or nitrous delivery. Instead, I suggest the use of liquid Teflon thread sealant on all pipe thread fittings. AN fittings don’t need any sealant at all.
Also, if you are feeding off the rail the fuel system must be able to support the amount of horsepower that the car is making on nitrous. For example, if you have a 255lph fuel pump on a car that is making 450whp NA that is totally fine. The problem arises when you try to support another 150whp from your nitrous kit. The fuel pump cannot keep up, fuel pressure will drop, and the car will run lean. To remedy this problem, I typically suggest a secondary, dedicated fuel system for the nitrous kit. A small cell with its own fuel pump and regulator will supply fuel to the nitrous system. You can also use higher octane fuel in the cell in order to help support a higher-powered shot of nitrous.
Turbo and Supercharger
In addition to this list of tips for prepping your turbo or supercharged vehicle it is also important to go over the items in the basic preparation list. These items are all the more important when adding boost.
- Check your piping for boost leaks: Always check your system for boost leaks. Use of good clamps and silicone couplers is very important. If pipes are constantly blowing off during the tuning process that is going to slow things down a lot and also it will be a great annoyance to you once you start driving the car. ***Intercooler pipes should have bead rolled ends or alternatively you can weld a few beads along the edge. This will give the clamps something to hold on to. Straight cut pipes are a no go. ***
- Proper routing of lines to blow off valves, wastegates and boost controller. If you don’t know or need a diagram just ask.
- Wastegate: For turbocharged applications this is one of the most important pieces of the system and it is often misunderstood how this operates. At minimum, you will need to know the boost level your wastegate spring is rated for. It must also be of the proper size to vent enough exhaust to slow down the turbine wheel. In addition to proper sizing, the wastegate needs to be installed in the exhaust in the proper location of the exhaust manifold or turbo hot side merge for it to function. Please ask questions or send pictures if you are unsure of any of these things.
- Boost control: there are many different types of boost controllers out there. What is right for you will be determined by the use of the car. For any type, diagrams can be provided to show you how to properly set it up to prepare for your tune.
- Supercharger belt should be replaced if it has not been replaced recently. A slipping belt will cause boost to build slowly, fall off early, or sometimes not build at all. Tensioner operation and belt alignment must also be checked. Improper alignment of the belt or a failing tensioner will cause the belt to be damaged and/or break. When a belt breaks at high rpm it can take out important and sometimes expensive components around it. If any of these things aren’t right you’re not going to have a successful tune appointment.
- Colder spark plugs will need to be installed. Heat range will depend on boost/power level. Also on a boosted application the spark plug gap will be considerably smaller than a naturally aspirated setup.
- Sensors: The stock map sensor on most naturally aspirated vehicles cannot read positive manifold pressure. This will have to be upgraded. Sensor type will vary depending on the vehicle, but typically an upgrade to a 2, 3, or 4 bar would be the choice.