Help with driveability problems.
05-11-2006, 09:09 PM
#1
Help with driveability problems. i bought my 97 Z28 with a rod knock so i have no clue if this was a problem before i had the motor out but i dont think it was. once my car runs long enough to go into closed loop it runs like *** at part throttle (it actually cannot keep a steady speed if you are gentle with the throttle) and it hunts for an idle, the first mile or two it is perfect. looking at live data on the tech2 it is pulling out up to 33% on short term fuel trim, timing goes down to 20ish from 36-40 degrees, egr duty cycle goes up to 100%(even with vacuum line disconnected). as you give it more throttle nearing 70% it goes out of 'fuel control learned' to 'unlearned' and all the parameters go back to normal (it says it is in closed loop still) and accelerates fine. it has codes for running rich and egr insufficient(i cant remember if the EGR codes were there before i disconnected it). i checked all my grounds (the battery ground at the block, the one above the starter, the strap near the AIR pump to the frame and the battery to strut tower) using a voltmeter and none were above .5 ohms (i did not check voltage drop, the car seems to start just a minor bit lazy like a weak chassis ground so i will do that next) I might try a reflash but i dont think thats the problem. Any help would be appreciated. thanks, rich 
05-26-2006, 08:47 PM
#2
ok, with the front O2s unplugged the car runs perfect at all times. if you watch the rear O2s they are staying in the .800v range so the car is running rich at all times and the pcm is pulling fuel out to compensate causing it to run like ****. all sensors seem to have good values and i tried reflashing to no avail. thanks for any help.
05-29-2006, 11:02 PM
#4
Originally Posted by WhiteSSP
If it runs fine with the Front o2's unplugged, you just found your problem.
i will try to replace them but they seem to be working fine.
with them plugged in you can watch them go from rich to lean when the pcm starts pulling fuel out. and with them unplugged and the car running smoothly you can watch the rear o2s staying rich all the time.
i will see in the next day or two.
