Issue maintaining idle....
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TECH Enthusiast
Joined: Mar 2002
Posts: 630
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From: York, PA
Issue maintaining idle.... Hey All,
Finally coming to an end with my setup and the car runs, but cannot maintain and idle.
TPS has been manually adjusted...
A new stock maf was put on the car (SLP maf was kaput)
My setup
heads/cam (230/230 114)
T-76
Q.m.p. manifolds.
TH-400
12-bolt
Aeromotive 1000 external pump.
1/2 tank gas.
Now my initial observations were that the car would have a bit of trouble starting but would when given some gas. It acted like the battery was dying.
Second, the car would have trouble maintaining idle rpm no matter what I set it to (initially 850, now 1000 rpm)
I noticed that when the car would lope below the idle rpm limit while idling the digital battery voltage meter I have read 11 volts. If I gave the car gas the volts would go up to 13 and stay there (the alternator doing it's job) Also I can hear the aeromotive pump whining down when the volts go down...
So my theory is, the Aeromotive pump isn't getting enough juice from the battery (prob. holding below 12 volts although I didn't have a chance to see it's voltage with the engine off... but that because the pump cant get full 12v, it's not feeding enough gas, and thus the problem idling.
What do you all think? Right now there's been some changes to IPR table for 57lb injectors, the higher-rpm VE and Ignition table portions which were done at Q.m.p. when the motor was stock heads/cam but other than that, the PCM is stock.
Finally coming to an end with my setup and the car runs, but cannot maintain and idle.
TPS has been manually adjusted...
A new stock maf was put on the car (SLP maf was kaput)
My setup
heads/cam (230/230 114)
T-76
Q.m.p. manifolds.
TH-400
12-bolt
Aeromotive 1000 external pump.
1/2 tank gas.
Now my initial observations were that the car would have a bit of trouble starting but would when given some gas. It acted like the battery was dying.
Second, the car would have trouble maintaining idle rpm no matter what I set it to (initially 850, now 1000 rpm)
I noticed that when the car would lope below the idle rpm limit while idling the digital battery voltage meter I have read 11 volts. If I gave the car gas the volts would go up to 13 and stay there (the alternator doing it's job) Also I can hear the aeromotive pump whining down when the volts go down...
So my theory is, the Aeromotive pump isn't getting enough juice from the battery (prob. holding below 12 volts although I didn't have a chance to see it's voltage with the engine off... but that because the pump cant get full 12v, it's not feeding enough gas, and thus the problem idling.
What do you all think? Right now there's been some changes to IPR table for 57lb injectors, the higher-rpm VE and Ignition table portions which were done at Q.m.p. when the motor was stock heads/cam but other than that, the PCM is stock.
Last edited by 02BlueFirehawk; May 16, 2005 at 07:52 PM.
run the car in open loop at startup, log wideband data (which you of all people HAVE to have 
) and try commanded a desired A/F. 12.0ish or something. That will clue you in on if your idle areas are running too rich or too lean. Then you will want to adjust your VE tables to produced your commanded AFR.
All that voltage stuff sounds more like your idle surge basically stalling out the car, and when the car aint spinnin, your battery goes to 11-12V. Keep a high idle for now, just to help it get off it's feet, then lower it to whatever you find appropriate.
Stock PCM + turbo ain't gonna run too hot... lol You did an upgraded MAP sensor as well correct? It would be a good idea to invest in a 2bar tuning software as well
) and try commanded a desired A/F. 12.0ish or something. That will clue you in on if your idle areas are running too rich or too lean. Then you will want to adjust your VE tables to produced your commanded AFR.All that voltage stuff sounds more like your idle surge basically stalling out the car, and when the car aint spinnin, your battery goes to 11-12V. Keep a high idle for now, just to help it get off it's feet, then lower it to whatever you find appropriate.
Stock PCM + turbo ain't gonna run too hot... lol You did an upgraded MAP sensor as well correct? It would be a good idea to invest in a 2bar tuning software as well
Originally Posted by 02BlueFirehawk
At idle the car is pegging 16:1 which I was told was way lean by the builder and absolutely normal for the f-body by a local tuner.
