Stuck Accelerator(Idle)

[kmschna]

After going highway speeds and letting off on the gas pedal, the car will continue to hold or loose speed down-to 53 mph. It will hold there for a minute or so, then drop to around 35 mph(depending on road and wind). The car will stay indefinitely at this speed. After applying breaks you can still feel the motor pushing and makes breaking harder. But after stopping, engine idle is normal, if only a little low.

I put in a new IAC and cleaned the seat, the only difference was 60 bucks. Vacuum hoses appear OK. A new computer fixed a misfire problem.

Any ideas, please.

89' Electra

[BNaylor]

Thread moved from Electra to Park Avenue at OP's request due to higher traffic and better chance of replies.

[HotZ28]

Have you checked for codes? Usually, the TPS will send a high ,or low voltage code for this condition. You could also have low fuel pressure and the ECM is trying to compensate by richening the fuel curve, therefore, altered idle speed. Check fuel pressure and TPS voltage at idle and partial throttle. Range should read, between .40v @ idle, to 4.5v @ WOT. Fuel pressure should be 38-45 psig @ idle.

[kmschna]

Originally Posted by HotZ28

Have you checked for codes? Usually, the TPS will send a high ,or low voltage code for this condition. You could also have low fuel pressure and the ECM is trying to compensate by richening the fuel curve, therefore, altered idle speed. Check fuel pressure and TPS voltage at idle and partial throttle. Range should read, between .40v @ idle, to 4.5v @ WOT. Fuel pressure should be 38-45 psig @ idle.

Thanks for your insight,HotZ28. Since the diagnostic learning curve is a little steep for me on this one, I threw 34 dollars at it instead. A new TPS is now installed and it did do something. The idle had been high while driving, now its high also at Park. My guess about 12 to 15 hundred RPM's. It also kicked an check engine light.

Get this, the light goes out on medium to hard acceleration and goes off at cruise or idle. Advanced Auto retrieved the codes for me and they are:

Current Code 22- Throttle Position Sensor Signal Voltage is too low

History Code 22- Throttle Position Sensor Signal Voltage is too low

BTW. No check engine lights before I replaced TPS.

I will have to find someone to check fuel pressure for me. Anything else that I might be able to do here?

'89 Park Avenue

Thanks