Edit: Correction to the initial post. After clarification with him, I misunderstood the issue. It does not seem to be hitting a limiter, it's just breaking up (missing) so bad that he's getting out of it by 4000 RPM to prevent engine damage.
Original post:
I just bought a '95 mustang from a friend for $4500 with one catch. It hits what seems like a limiter at about 4000 RPM. Can anyone provide a list of things that could cause this problem?
My friend is extremely mechanically inclined and this situation has us both stumped.
He test the coil's spark and said it was sparking, but based on the color it looked like a weak spark. So, he tried swapping the coil with another friend's mustang, but that did not change anything. He checked the timing which he stated was "rock solid" with the spout out. To me that indicates that it probably isn't the PIP/hall-effect sensor, as I would expect erratic timing if they were an issue. He tried removing the MSD 6AL and ran the car without it, and there was no change.
This really seems like an ignition issue to me, but he believed that it could be fuel issue. Initially he saw fuel pressure drop when the car hit the "limiter," but I'm convinced that would happen simply as a result of losing boost pressure from the turbos. He also said that the AFR was never worse than low 12s, which is kinda lean for WOT at 10 psi boost, but not bad enough to act like a limiter and probably not even enough to cause detonation.
Car's mods:
Engine:
GT40X heads
Edelbrock Performer 5.0 intake (fox-style)
unknown (but probably stock HO) cam
1.72 FMS rockers
Incon twin-turbo kit
Fuel:
Walbro 255 LPH pump
AFPR
42 lbs/hr injectors
in-car fuel pressure guage
Tuning:
MSD6AL box (he removed this and it did not change the problem)
Tweecer RT
Wideband O2 with gauge (innovate brand, I think?)
Drivetrain:
6spd transmission ('03 Cobra)
I'm not sure if I missed anything, but if I get a chance, I'll have him jump on here to further clarify what he's done and any other mods I left out which may affect the problem.
Thanks for any ideas.
Original post:
I just bought a '95 mustang from a friend for $4500 with one catch. It hits what seems like a limiter at about 4000 RPM. Can anyone provide a list of things that could cause this problem?
My friend is extremely mechanically inclined and this situation has us both stumped.
He test the coil's spark and said it was sparking, but based on the color it looked like a weak spark. So, he tried swapping the coil with another friend's mustang, but that did not change anything. He checked the timing which he stated was "rock solid" with the spout out. To me that indicates that it probably isn't the PIP/hall-effect sensor, as I would expect erratic timing if they were an issue. He tried removing the MSD 6AL and ran the car without it, and there was no change.
This really seems like an ignition issue to me, but he believed that it could be fuel issue. Initially he saw fuel pressure drop when the car hit the "limiter," but I'm convinced that would happen simply as a result of losing boost pressure from the turbos. He also said that the AFR was never worse than low 12s, which is kinda lean for WOT at 10 psi boost, but not bad enough to act like a limiter and probably not even enough to cause detonation.
Car's mods:
Engine:
GT40X heads
Edelbrock Performer 5.0 intake (fox-style)
unknown (but probably stock HO) cam
1.72 FMS rockers
Incon twin-turbo kit
Fuel:
Walbro 255 LPH pump
AFPR
42 lbs/hr injectors
in-car fuel pressure guage
Tuning:
MSD6AL box (he removed this and it did not change the problem)
Tweecer RT
Wideband O2 with gauge (innovate brand, I think?)
Drivetrain:
6spd transmission ('03 Cobra)
I'm not sure if I missed anything, but if I get a chance, I'll have him jump on here to further clarify what he's done and any other mods I left out which may affect the problem.
Thanks for any ideas.
