I'll make this quick and to the point, looking for some help: I will list the symptoms, then what I have done so far to try to resolve the issue
WHAT I HAVE:
2003 GT with 4v swap, new factory 01 Cobra block and intake, 04 Mach heads decked .010", JLT Ram Air, Sniper Bazooka 95mm MAF, Delphi 42lb Injectors, T56, ARH longtubes and O/R x, EGR delete, UDP's, Intake spacer etc
PROBLEMS:
In Neutral, I cannot hold the RPM's at 1500. The throttle seems jumpy up to about 2000. After 2000 still in N, I can hold any RPM I desire, but from 1000-2000, the car repeatedly burbles back down to idle, even with the throttle pressed. It also seems as though the car doesnt react to the throttle until it is depressed enough to make it go to 2000, then when I try to back it down to 1500, it burbles to idle (SEE VIDEO)
When the TPS sensor is disconnected, I can hold the RPM's at 1500 no problem and it is much smoother.
In 3rd or 4th at WOT, there is a small hiccup at 3000, larger hiccup at 3500, and backfire at 4000rpm. This happens almost all the time, but once in a while it will be fine. This also happens more sporadically at part throttle and lower RPMs. This is regardless of whether the tune is rich or lean, same mechanical issue is present at the same RPM. During the split second of each hiccup, it shows lean (Also, SEE VIDEO). I really hope these problems are related, so I'm only chasing one problem, instead of several
WHAT I HAVE DONE:
Replaced MAF, Injectors, TPS, disconnected one COP at a time to see if the issue persisted and there was no difference in having any one COP unplugged, as there would be with all of them plugged in. The Cam and Crank position sensors are new, but I suppose I could try to throw in my old ones. O2 Sensors are new Bosch sensors.
We have restarted the tune 3 times and triple checked everything in it, also the parameters are about the same on several other cars that do not have this problem. I am definitely have a mechanical issue somewhere, not a tuning issue.
I pulled the plugs and they look fine, they are NGK T55's.
VIDEOS:
Here is a video of the idle burbling back down:
Won't hold 1500 or 2000 in N - YouTube
And here are the hiccups:
Hiccups at part throttle - YouTube
Really need some help here, I'm at wit's and money's end. Thought it couldve been the PCM but it is sporadic. Not all the time. Also thought about the wiring I had to do to the engine harness for the COP's but I feel very confident with my wiring capabilities and know that every solder was solid. If you dont know of anywhere else to look, maybe you can forward this to somebody that can. Thanks
WHAT I HAVE:
2003 GT with 4v swap, new factory 01 Cobra block and intake, 04 Mach heads decked .010", JLT Ram Air, Sniper Bazooka 95mm MAF, Delphi 42lb Injectors, T56, ARH longtubes and O/R x, EGR delete, UDP's, Intake spacer etc
PROBLEMS:
In Neutral, I cannot hold the RPM's at 1500. The throttle seems jumpy up to about 2000. After 2000 still in N, I can hold any RPM I desire, but from 1000-2000, the car repeatedly burbles back down to idle, even with the throttle pressed. It also seems as though the car doesnt react to the throttle until it is depressed enough to make it go to 2000, then when I try to back it down to 1500, it burbles to idle (SEE VIDEO)
When the TPS sensor is disconnected, I can hold the RPM's at 1500 no problem and it is much smoother.
In 3rd or 4th at WOT, there is a small hiccup at 3000, larger hiccup at 3500, and backfire at 4000rpm. This happens almost all the time, but once in a while it will be fine. This also happens more sporadically at part throttle and lower RPMs. This is regardless of whether the tune is rich or lean, same mechanical issue is present at the same RPM. During the split second of each hiccup, it shows lean (Also, SEE VIDEO). I really hope these problems are related, so I'm only chasing one problem, instead of several
WHAT I HAVE DONE:
Replaced MAF, Injectors, TPS, disconnected one COP at a time to see if the issue persisted and there was no difference in having any one COP unplugged, as there would be with all of them plugged in. The Cam and Crank position sensors are new, but I suppose I could try to throw in my old ones. O2 Sensors are new Bosch sensors.
We have restarted the tune 3 times and triple checked everything in it, also the parameters are about the same on several other cars that do not have this problem. I am definitely have a mechanical issue somewhere, not a tuning issue.
I pulled the plugs and they look fine, they are NGK T55's.
VIDEOS:
Here is a video of the idle burbling back down:
Won't hold 1500 or 2000 in N - YouTube
And here are the hiccups:
Hiccups at part throttle - YouTube
Really need some help here, I'm at wit's and money's end. Thought it couldve been the PCM but it is sporadic. Not all the time. Also thought about the wiring I had to do to the engine harness for the COP's but I feel very confident with my wiring capabilities and know that every solder was solid. If you dont know of anywhere else to look, maybe you can forward this to somebody that can. Thanks
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