Quote:
Originally Posted by vettestr
Hey Gang,
I have an older Pro-jection 4DI system. I am half a$$ed decent about tunning this but am a bit lost or keep overlooking the same thing.
The only symptom is what acts like a lean condition stumble only at light cruz. If at say 2500 RPM and just maintaining that speed the cam is happy and engine is smooth, no ignition issues found but a light hesitation starts, can not see RPM loss but can just feel it. The 02 sensor readings are 0.70ish at this point ??? Any throttle increase or decrease stops the very light stumble. I have fattened up the range but no help.
What am I missing here gang?
Your help and ideas are appreciated.
THANKS Jeff C
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Jeff,
Does your EFI system have a data recording capability? If so, I'd suggest you record the following when you make the problem happen: Target and Actual A/F Ratios, ignition timing, acceleration enrichment (both TPS and MAP-based, injector pulse width, MAP Senor (or load), VE %, and RPM. If you post this data, we can probably figure out what is going on. Is the RPM and load point where you are having the problem between VE table entries? If you are splitting adjacent cells, are there big differences between the cells?
BTW, this is a pretty common problem. I've had basically the exact same experience with 2 EFI controlled engines I've built. It should be easy to tune out.
- Fred