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I have a 98 corba with a 4.6 bored .20 over, forged, ID 1000, return style fuel system, aeromotive regulator, stock cams, Kenebell 2.6 wit a ported intake running about 21# of boost. I have recently smoothed out the timing tables, was looking to dial in the afr up top but wanted to get the idle down before i started on that. Long story short i was chasing a broken down coil months ago, car would break up when at wot. I gapped the plugs down to .21(running Br7ef) and also compensated alot of fuel up top. So the car was running very rich! Now fast forward and im dialing in the idle. I have had the car idling around 850 rpm with the iac disconnected no issues. after getting the idle screw set i then connected the iac and messed with those settings. Once again had the car idling for 30 minutes as i fined tuned the iac settings. I could rev it and it would come back down and resume idling at 850. Then when i would take it down the street and do some WOT pulls the car would surge and stall after i pushed the clutch pedal in. I have attached my tune file and my datalog sheet for your review. I feel that my injector file may be wrong? I have verified that i have 43.5psi at the rails with no vacuum to reference on the regulator. Also i feel that the VE table values are high and that also makes me think the injector file is wrong.
Its strange because the car ONLY has issues idling after i do a WOT pull under very rich conditions. The car also feels great under WOT, just needs to be leaned out. My next plan is to put a fresh set of plugs in the car along with widening the gap to about .26-.28 seeing how the car responds to that. I started this thread as a brainstorming venture to see if maybe someone else from the outside looking in could see something i dont. Let me know!
says i cant post my datalog/tune file. How do i post that?
put your file in a ZIP file (in Windows - Right click and use Send->Compressed (zipped) Folder). You can attached a .zip file.
Your idle problem may be fixed when the WOT over rich condition is solved. Why don't you solve that problem first then see if you still have an idle problem.
Do you have Decel Fuel Cut-Off (DFCO) enabled? Using that might allow recovery from the excess WOT rich condition.
The car runs rich at wot not idle. Ill check decel setting and post logs shortly!!!
see attached log
Another thing i noticed last night was that the fuel pressure at the rails with no vacuum to reference measured 43psi yet when i prime the pump my fuel pressure regulator wont hold pressure. IS that a sign that the pressure regulator is failing or is that common in return style systems?
Lose of fuel pressure when the pump isn't running is common unless there is a check valve between the pump and the fuel pressure regulator.
Ok thats what I thought. I have an aftermarket alternator that runs at pretty much 14 volts at all times since I have a high demand on the system. I think my fueling and ve tabke issues js due to the dead time values. The deadtime valves for the 14v column is like 87%. Would changing that to 100% correct this issue you think?