EFIDynoTuning Forum

Hello I have an 04 mach 1 with a 4r75. I'm chasing down a weird issue and im wondering if there is something in the tune that would cut random cylinders off at high load low rpm. my car is stock other than 4:10 gears, high flow cats, jlt air filter, walbro 255 and a 91 octane vmp tune. I recently put drag radials on and now that I have traction when I go to launch the car or do a burn out the car fall on its face. after that it runs perfectly throughout the rest of the rpms. using ids I have verified short trims fall to -14% both banks when its happening, they remain +-5% in all other scenarios. power balance shows 1 cylinder on each bank drops out if I let off and get back into it 2 different cylinders drop out and so on. I've replaced the spark plugs and maf with new. i have swapped coils, iac, fpdm, dpfe, frp sensor from my other car and cleaned pcm grounds. when I disconnect the maf it is better and will do a burnout but overall drivability is poor and will hardly idle

sounds like u didnt turn the traction control button off on the dash?

That thought crossed my mind as well and that’s almost what it seems like but the car had no problem spinning the old tires. The guy I bought the car off told me the traction control is turned off in the tune and pushing the button doesn’t turn the traction control light on/off.

if the idle and all is jacked then you peob have something mechanical going on

what tuning hardware do u have?

It idles great and has good drivability over all just when you brake torque it to launch or try and brake torque and burnout it missfires and falls on its face it currently has an sct programming it but I have purchased a quarter horse as I am collecting parts to do a kenne bell and forged motor soon but I want to get this issue ironed out before I start really modifying it

Does it pop through the air filter when you brake torque it? I found that's normally an indication of being lean.

I had a goofy issue with my 5.0ho and an sct tune. Got my base from Lasota Racing, and it would drop cylinders like torque management / trac control was kicking in somehow. It would do it at the damndest times. It seemed like a hardware/engine issue. Lucky for me, I had it running prior to that tune and never had that issue. It had to be something in that tune. I tracked it down to something with the rev limiter settings. I don't know exactly what, and Lasota basically told me I was nuts. It never did it again after I eliminated his rev limiter files though.

I’ll try and reflash back to stock and see if it changes anything. It doesn’t backfire through the intake I don’t have the wideband hooked up yet but the stft on both banks drop to -14% while it’s doing it

yeah if they switch to a set lambse then its a limiter its hitting

So I flashed it back to stock and it still has a little stumble but it does actually spin the tires now. I need to do a bit more testing and data logging when I get some free time but I’m wondering if I should just have you write me a tune decipha. I am collecting parts so far I have a forged engine with shm blower cams and a kenne bell 2.1 supercharger, long tubes and am planning to swap it over the winter so I was going to do the premium membership and have you tune my car anyways