Surging at slow speeds
07-06-2005, 02:24 AM
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Surging at slow speeds
My 951 has always done this when I cruise in traffic at low speeds. Just coming off idle it surges ahead, then comes back to idle. This keeps repeating and I can't feather the throttle to stop this. The car runs great otherwise, no problems at any other speeds. Is this normal? It doesn't really affect the driveability of the car, just annoying. Nothing specific to this in old threads. Thanks.
07-06-2005, 11:57 AM
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Make sure it is adjusted properly before you go replacing it. I had the same problem, and the TPS and just loosened up and slid around a bit. . .
If you don't know how to adjust it, I think www.clarks-garage.com has a good write up on it.
If you don't know how to adjust it, I think www.clarks-garage.com has a good write up on it.
07-06-2005, 12:10 PM
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Yep. TPS or possibly a vaccum leak. It can be adjusted also to set the "idle" position just before the cam comes off the post - check that and you might be able to save a few bucks by a minor adjustment.
07-06-2005, 12:31 PM
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Yep. I definitely agree to check first. It's one of the easiest things to do on these cars. Frankly, it's even simpler than Clark's write up. However, yours are classic symtoms of TPS failure. Mine were precisely the same. Check very carefully around the connectors wires, also. If you're still not sure, unplug the TPS, , thus eliminating it from the equation. It's sort of addition by subtraction. Isolate it out of the loop. Yopur car will run about 3 to 500 rpm higher at idle, and run a hair rich, but it will be fine. If it runs smoothly that way, then you have drasticly narrowed you search.I did all of the Vac leak, fuel line/filter/ ground chasing, youo can imagine. I found a lot of auxilary issues, but never cured the prob. until the TPS was removed from the equation. Insta fix. If you don't know what it looks like, go buy the Haynes Manual. It's a good picture book.
07-06-2005, 03:12 PM
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You might also check the wiring to the connector for the TPS.
Under the rubber boot on the backside of the connector.
I've found three diff connectors that the wires were brittle and cracked.
Easy way to do this is to run a continuity check on the individual wires while bending the harness near the boot.
Under the rubber boot on the backside of the connector.
I've found three diff connectors that the wires were brittle and cracked.
Easy way to do this is to run a continuity check on the individual wires while bending the harness near the boot.