I have an EFI 351W in a '90 coupe which will not rev past about 6000 RPM. When it gets to that point, it falls flat and burbles and pops as if it was having an ignition misfire. This problem happens at WOT and part throttle, with the stock A9L program, a modified Tweecer program with higher rev limiter, and with a Ford RPM Extender with a higher rev limit. Datalogs indicate that the air/fuel ratio is fine, even at the point where it falls over, and this coupled with the fact that the problem happens at part throttle too seem to point away from a fuel pump or injector capacity problem. The ignition is a new Mallory Hyfire VI-A and MSD HVC-II coil, and even with this new ignition the problem remains and is exactly as it was with the stock ignition. The cap and rotor are extremely low milage and look brand new. The distributor is also new, but is a truck distributor for an EFI truck.
The engine configuration is as follows:
- 351W, 11:1 compression, .030" over, balanced, square decked, torque plate honed, etc.
- Comp XR292R solid roller cam, 254/260 (@.050) duration, 621/627 lift.
- Victor 5.8 intake, ported
- TFS Track Heat heads, ported, 2.02" intake, 1.60" exhaust
- K-Motion K-800 springs, installed 1.78" high. About 190# seat pressure and about 450# open pressure
- 1.75" long tubes, 3.5" dual exhaust.
- Mallory Hyfire VI-A ignition, MSD HVC-II coil, Ford EFI truck distributor and TFI module.
- A9L EEC-IV engine control, with Tweecer
- 90 mm throttle body, 95 mm MAF, 30# injectors, 190 LPH in tank fuel pump
- Engine is naturally aspirated.
I am looking for any considered opinions on why this engine cannot rev past 6000 RPM. Mechanically, I don't see any reason why it shouldn't, but I am starting to run out of ideas. What do you think?
-Matthew
The engine configuration is as follows:
- 351W, 11:1 compression, .030" over, balanced, square decked, torque plate honed, etc.
- Comp XR292R solid roller cam, 254/260 (@.050) duration, 621/627 lift.
- Victor 5.8 intake, ported
- TFS Track Heat heads, ported, 2.02" intake, 1.60" exhaust
- K-Motion K-800 springs, installed 1.78" high. About 190# seat pressure and about 450# open pressure
- 1.75" long tubes, 3.5" dual exhaust.
- Mallory Hyfire VI-A ignition, MSD HVC-II coil, Ford EFI truck distributor and TFI module.
- A9L EEC-IV engine control, with Tweecer
- 90 mm throttle body, 95 mm MAF, 30# injectors, 190 LPH in tank fuel pump
- Engine is naturally aspirated.
I am looking for any considered opinions on why this engine cannot rev past 6000 RPM. Mechanically, I don't see any reason why it shouldn't, but I am starting to run out of ideas. What do you think?
-Matthew