1994-2002 [Subscribe to Daily Digest] |
I've been having problems with my idle surging, racing, and idling way too low. The problem all started after I removed my throttle bracket to modify it for a WOT switch. I didn't realize at the time that it also served as the throttle stop. Well I finally got the specs for the TPS signal from townsend's website. It should read ~.7 volts at idle on the signal wire. It should be noted that the wire colors in the diagrams didn't apply to my '97. I pulled my IAc valve and hoses to get better access to the harness for the TPS. I then deducted which wire was my signal, on mine it was the red/green wire. I loosened up my set screws and cranked my engine and monitored the voltage on the signal wire as I moved things around. This proved very insightful. Below .65 volts the engine surged quite noticibly, much like when it was acting up. I found this odd, since my IAC wasn't controlling airflow, I was restricting the lower idle air port to get a near idle air flow into the intake. It seems the ECU was causing the surging by adjusting the fuel mixture back and forth. When I adjusted my throttle stop to the .7 volt setting it actually opened the throttle plate a little raising the idle. I settled on .694 volts at idle with the engine running. This gave me .674 volts without the engine running. Since these are both above the .65 volt surge threshold and gives close to .7 volts without opening the throttle plate, I feel I've finally got this nagging problem beat. After clearing the adaptation and restarting the car I got the best idle I've had in few months.(since I screwed with it) It seems like there is a very small window for correct idle signal despite the Townsend site's info stating that the check engine light will only give a TPS code if the voltage is below .2 volts at idle or above the 4.whatever volts at WOT. Only 5 tenths of a volt from spec was causing serious surging during this test and fix session. For those suffering similar symptoms, hopefully this info can help fix a few of them.
posted by 216.148.24...
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
![]() |
![]() |
![]() |
![]() |
![]() |