RPM increase when braking.


dwhisent
10-12-2006, 10:28 AM
92 PA, 111000 miles.

This may be a tough one to track down, it only very rarely happens.

Occasionally, when braking, when almost stopped, the RPMs kick up, trying to increase and fighting the brakes, until I quickly pump the brake. It then drops back down to normal idle. I have had this happen after driving 30 miles at 55-60 and stopping at a stop sign, and also after just starting cold, moving slowly through a parking lot, and stopping at the exit. I can sometimes go for days with this not happening, but then it may happen 3 times in one day.

I do have the SES light showing, and it is indicating a bad cam or crank sensor. However, the SES light first came on when my A/C compressor clutch self-destructed and pinged around the engine compartment, probably cracking something or breaking a wire. The bad RPM behavior started before this happened, and the SES light was not illuminated at the time.

I have had suggestions of vacuum problems or a bad front lower engine mount.

Any other ideas? Or opinions on these two ideas?

Thanks.

Bassasasin
10-12-2006, 01:49 PM
A possibilty is the Cruise Control vaccum assist diaphram is pulling on your throttle somehow..
As I understand it there are little electic valves controlled by electronics it has a release vaccum valve on the pedal.

You may have a bad TPS.Throttle Position Sensor.
They get bad often in that range and not bad to replace... find a junker and see if the symptoms change.

A responsible option is to look at the codes.
Not sure if a code will show but its good to know where you stand.

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