No Idea...Need Some Help. 91 vert
08-14-10, 11:21 AM
#1
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No Idea...Need Some Help. 91 vert
My car isnt running well and I'm having trouble figuring out the problem. It runs rich and will stumble/hesitate when on throttle. When I rev it up and let off it will drop down to around 500 and then itll raise back up to around 750. In gear and just trying too maintain speed feels like riding a bull. I just changed out the exhaust to a racing beat and put in a new fuel pump. I've done numerous tests to see what/where this problem might come from. Here are the tests:
FUEL PSI - perfect pressure at idle and rev
Back pinned all sensors at the cpu for proper voltage including: Air temp (at airbox and engine), water temp, pressure sensor)
BAC Valve works fine
Spark is fine
I'm not sure whether an exhaust could do this to a car but it ran fine with the new exhaust on it for a couple of days and then started to act like this. It has a generic O2 sensor in it. Any ideas, suggestions, advice would be appreciated. Everything is stock but the exhaust.
FUEL PSI - perfect pressure at idle and rev
Back pinned all sensors at the cpu for proper voltage including: Air temp (at airbox and engine), water temp, pressure sensor)
BAC Valve works fine
Spark is fine
I'm not sure whether an exhaust could do this to a car but it ran fine with the new exhaust on it for a couple of days and then started to act like this. It has a generic O2 sensor in it. Any ideas, suggestions, advice would be appreciated. Everything is stock but the exhaust.
08-14-10, 11:24 AM
#2
Check the TPS and adjust it as necessary using OHMETER to test for dead spots, then use a VOLTMETER to adjust it to 1V DC while back probing the green/red wire and having the initial set cable JUMPED to ground.
Pull codes to make sure nothing is obviously disconnected or not working well.
After doing both, report back if problem persists.
The idle dropping to 500 and back to 750 is fine, that would only be a problem if the car dies after letting off the throttle. The BAC is compensating for the idle drop as it nears 500. While doing the TPS adjustment and having the initial set connector grounded, you can adjust the idle to 750 if it is higher or lower after grounding the initial set connector. Adjust idle via the screw on top of the throttle body.
Pull codes to make sure nothing is obviously disconnected or not working well.
After doing both, report back if problem persists.
The idle dropping to 500 and back to 750 is fine, that would only be a problem if the car dies after letting off the throttle. The BAC is compensating for the idle drop as it nears 500. While doing the TPS adjustment and having the initial set connector grounded, you can adjust the idle to 750 if it is higher or lower after grounding the initial set connector. Adjust idle via the screw on top of the throttle body.
08-15-10, 12:24 PM
#4
I saw your other post here: https://www.rx7club.com/showthread.p...t=exhaust+leak
This IS an s5. Are you sure you have no codes? Sounds like it may be in limp mode due to a bad oil metering pump or possibly a blown rotor if it is running rich. Exhaust leaks generally will not cause the car to buck and run crazy rich. These are also symptoms of a unplugged or bad Air Flow Meter!
Check compression on the rotors would be something I would do right away. Followed by double checking for codes and checking the AFM.
This IS an s5. Are you sure you have no codes? Sounds like it may be in limp mode due to a bad oil metering pump or possibly a blown rotor if it is running rich. Exhaust leaks generally will not cause the car to buck and run crazy rich. These are also symptoms of a unplugged or bad Air Flow Meter!
Check compression on the rotors would be something I would do right away. Followed by double checking for codes and checking the AFM.
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