1995 subaru legacy with 133,000 miles. car would not start in park.key would turn fully with no sound at all. moved shifter around then back to park and was able to start car.car now revs excessively, but not at all times.can also feel vibration while driving.all of this began simultaneously with the appearance of the check engine light! threads on this forum seem to point to the throttle position sensor.have no computer diagnosing equip.do these problems point to the tps? where is it located? should i clean or replace?earlier threads make it seem more difficult then just screwing a new one in place. if two screws hold it in position ,won't it fit in only one position ?any and all help is greatly appreciated. thanks

Welcome to the forum.

 

It would be easier to diagnose the problem if we had the trouble code, but the symptoms alone might point in a particular direction. Intermittently not being able to crank the engine when in Park probably means the inhibitor switch is acting up. That can cause other problems, if the ECU doesn't know what gear is selected. See http://endwrench.com/images/pdfs/Diagnostic.pdf .

Take it to most any autoparts place and they will read the codes for free. Just ask them for the code # and post them back here or search the USMB for that code/s.

 

If it does not start in park try it in "N"

Whatever the problem is, it isn't the TPS. Don't mess with it.

 

No engine can "rev excessively" without an air supply. You have an air leak somewhere. Anything different with the brakes? Could be a leaking brake booster.

Edited September 14, 200916 yr by john in KY

Get the codes first. The high idle can be caused by the inhibitor switch. The check light can be caused by the inhibitor switch.

A bad TPS can certainly cause excessive revving of the engine. I've had it happen. Nearly ran into the back of another car the first time it happened.

 

But you should get the codes checked before pointing the finger at one specific part.

Whatever the problem is, it isn't the TPS. Don't mess with it.

 

No engine can "rev excessively" without an air supply. You have an air leak somewhere. Anything different with the brakes? Could be a leaking brake booster.

john, the brakes went hard at one time when this happened.

Power booster could be bad or the check valve. Just disconnect the vacuum hose at the booster, plug it and see if the idle improves. Don't drive the car when doing this.

A bad TPS can certainly cause excessive revving of the engine. I've had it happen. Nearly ran into the back of another car the first time it happened.

 

But you should get the codes checked before pointing the finger at one specific part.

 

How that could be possible is a mystery to me. Not flaming you, just can't imagine how that could be possible.

Power booster could be bad or the check valve. Just disconnect the vacuum hose at the booster, plug it and see if the idle improves. Don't drive the car when doing this.

john, just drove car to auto store for computer diag.car drove fine no problems.put on machine came up wth code PO302 .it read cylinder misfire. i think no 2.auto store worker erased cel.started car to leave and car would not idle smooth.would stall if foot not on gas.cel light did not come back on. drove home using gas and brake to keep from stalling.car did not skip or hesitate at normal driving speed .only at very low rpms or stops,where it wanted to stall.brakes worked fine.do you still think it could be booster or does this info point elsewhere? thanks for reply

Well basically the TPS gets a "dead spot" where the ECM reads no input from the TPS. It gets confused and can sometimes result in the computer advancing the ignition timing and fuel mixture to what it would be at WOT. Engine revs and you take off. And trust me, it is not fun. Happened to me with an 89 Chevy Corsica I had years ago. Took off on me when I was trying to slow down for a red light. Luckily I knew enough to throw the thing in neutral, and it promptly red lined and started bouncing on the rev limiter. I killed the ignition and had it towed home. Started it at home and it was fine until I touched the gas pedal, it shot straight up to red line again. Put a new TPS on it and no more problems.

Now that could be chalked up to the programming of the ECM, I have no idea if a Subaru would react the same.

Take it to most any autoparts place and they will read the codes for free. Just ask them for the code # and post them back here or search the USMB for that code/s.

 

If it does not start in park try it in "N"

 

got code from auto store.it is PO302.read engine misfire #2 cylinder. at this time car ran fine, so he cleared cel. as soon as he did this, i started car to leave and car would not idle and stalls.cel has not gone back on. drives fine but will not idle.no engine race.any suggestions. thanks.

Look at the plugs, are the all the same color? They should all be very light tan if things are working correctly.

 

Could be an Injector, Plug, Plug wire, bad compression

Still sounds like a vacuum leak to me. Intermittent problems are the worst. Try cleaning the MAF sensor, check over all of the vacuum lines to be sure you don't have any leaks. If the hoses are really hard they should just be replaced.

Make sure the hose clamps on the intake pipe are tight too.