exdeath
Lifer
- Jan 29, 2004
- 13,679
- 10
- 81
Adding to the list of "other things" is throttle position sensor. The computer uses a MAP or MAF sensor to estimate air intake and compute fuel requirements under steady state operation or gradual changes over time. However when you suddenly go wide open, it needs to plan ahead, and uses the TPS to provide enrichment in anticipation of more air coming in when you floor it (WOT power enrichment, same purpose as the accelerator pump in a carb).
It seems that it only dies when you go wide open from a low speed but is fine if you gradually speed up, so it makes sense that it might be related to wide open power enrichment functions.
Fuel pressure is also a good thing to monitor; fuel pump or regulator, especially a vacuum controlled regulator that might not respond fast enough to a sudden change in manifold pressure. Could also be the one way check valve in the pump not able to hold a sudden pressure spike when the regulator blocks the return path to increase fuel pressure.
The key here is that you have no problems through the RPM range if you gradually accelerate, so you need to look at things that come into play when there is a sudden instant change in throttle angle.
I doubt it's timing because a) no problems any other time at high or low revs if gradual, and b) timing is something that gradually changes with engine RPM, not instantly in any way that would cause hesitation when going wide open. The total timing at any RPM is fixed based on the base timing and the advance function, and is soley a function of the crank position and RPM and has nothing to do with throttle changes.
It seems that it only dies when you go wide open from a low speed but is fine if you gradually speed up, so it makes sense that it might be related to wide open power enrichment functions.
Fuel pressure is also a good thing to monitor; fuel pump or regulator, especially a vacuum controlled regulator that might not respond fast enough to a sudden change in manifold pressure. Could also be the one way check valve in the pump not able to hold a sudden pressure spike when the regulator blocks the return path to increase fuel pressure.
The key here is that you have no problems through the RPM range if you gradually accelerate, so you need to look at things that come into play when there is a sudden instant change in throttle angle.
I doubt it's timing because a) no problems any other time at high or low revs if gradual, and b) timing is something that gradually changes with engine RPM, not instantly in any way that would cause hesitation when going wide open. The total timing at any RPM is fixed based on the base timing and the advance function, and is soley a function of the crank position and RPM and has nothing to do with throttle changes.
Might have to do some timing retard then, but sooooo worth it...
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