One of the biggest sources of frustration and additional tuning costs we see is cars showing up without any preparation for the big day. Avoid disappointment and extra charges by performing the following checks listed in order of how often we see them ruin the day.
#1. Spark plugs and wires / boots should be NEW and should be gapped accordingly. Even if you are quite sure they are ok. A misfire will often only show up under heavy load half way through the tuning process and its likely your car will be making more power and more load than it ever has before. Not to mention it takes very little untuned or badly tuned runtime to kill spark plugs.
#2. Verify your front oxygen sensor / sensors are functional. This is REQUIRED. We do not do open loop tunes. Period. Call us if you are not sure. Every narrowband o2 sensor needs to be bouncing from below .45v to above .45v constantly as shown below. Wideband sensors need to be reporting something other than full rich (10:1) / full lean (18:1). Closed loop status on the scantool needs to be “Yes” or “Closed Loop” not open loop. Short and long term Fuel trims should not be stuck at 0% they should be moving and have a number other than 0%. You should have no codes for front (B1S1 or B2S1) o2 sensors or the related o2 heater circuits.
#3 If you have done an engine swap with a stock ecu and you got your harness from ebay or amazon it likely is going to have issues. Very common is non functional o2 sensors and MAF. A good rule of thumb for LSx engines is that if the harness cost less than $500 without the computers you are going to spend 4x what you saved in troubleshooting time. We condemn roughly 50% of ebay harnesses before they even make it onto the dyno. Best bet is to order a quality replacement and reschedule. Or even better just buy an aftermarket ecu and harness whenever doing swaps so you can avoid all of the stock ECU hassles.
#4 Essentially all stock ECUs expect a wheel speed signal. If you are hooking up a manual or non electronic trans you need to find a way to generate this signal. LSx ecus in particular get unhappy and have a tendency to stall without it. I can typically make it work without but its far from ideal. Once again. Its often better just buy an aftermarket ecu and harness for swaps so you can avoid all of the stock ECU hassles.
#5 If you are substantially modifying the exhaust system (big single turbo for example) with a stock ecu the o2 sensors need to measure the same cylinders they measured BEFORE doing the turbo kit. And not a mix of all of the cylinders unless they did that originally. You cant put one in the crossover and one in the turbo downpipe for example or any other shenanigans.
#6. No exhaust leaks before and 18″ after the oxygen sensor / sensors. This means you actually need a minimum of 18″ of exhaust system. Without this the sensor cant work properly.
#7. Injector data is REQUIRED. You need to know EXACTLY what injectors are in your car and injector data MUST be available for them. By proxy this means no knockoff injectors. A good rule of thumb is that good injectors have plug and play tuning data (not a flow chart) for your exact platform available and published clearly online. If you show up the day of the tune and we have to “email for injector data” we are at a standstill until it shows up. We do not tune decapped or no data injectors. Period. When in doubt contact us and ask.
#8. Size your injectors appropriately. Putting Bosch 210lb injectors in to everything just because they are cheap does not make them a good choice for your 450hp v8 setup that could easily run 50lb injectors. Especially on stock computers since they often require huge compromises to make these giant injectors work. Your car WILL run better with a reasonably sized injector.
#9. Scan for codes / errors BEFORE you show up even if your car is not yet running. Then contact us with the list so we can help you figure out what matters and what doesn’t.
#10. A fresh battery. We cant start your car if the battery is dead and it takes valuable time to charge.
#11. Fix major electrical / mechanical issues before you show up. They all affect the tuning process including brakes and tires that are unsafe or a transmission that is acting up. We understand your car is a work in progress but changes made after tuning will mess up the tune and require rework.
#12. Have the correct fuel in the tank and make sure there is plenty of it. If you bring your car with 87 in it we are tuning it on 87. If it has E85 in it we are tuning it on E85. Only exception is flex fuel tunes. Generally those go best when the tank is 1/4 full of the gas of your choosing. Then bring 10 gallons of e85 for us to add once we get to that stage.
#13. Beware of the xlink throttlebody adapter for 00-07 GM truck setups. WE CAN NOT TUNE OUT ELECTRICAL FAULTS. Sometimes they work. Sometimes they dont. We have a 50% failure rate on them. We have spent many hours troubleshooting them. Its a very touchy system and a very touchy way of fooling it. Best option is to use an upgraded housing with the stock electronics like the BBK 1757.
#14. If you are doing a 00-07 “LS” standalone harness and dont want to be stuck with the truck throttlebody make sure you order a corvette TAC module / harness and ls2 silverblade throttlebody (preferred) or ls3 throttlebody (less preferred).
#15. Clean your MAF and throttlebody. If I set your idle and MAF calibration when they are dirty its going to no longer be correct if you later clean these.
#16. Knock sensors are your friend. They are on essentially every single factory vehicle for a reason. They should be on yours too.
#17. Please do not bring in your car / truck filled with mud. I will ask you to go to a car wash first to avoid filling the dyno with mud.
Thank you for taking the time to go through this list. It will make everything go much smoother, save you money, and make your setup work better in the long run.