Jeep Wrglr-98 idles high after new TPS!

Joined
Jul 2, 2003
Messages
998
Location
Lexington, SC
I just replaced a TSP on my dau.s 1998 Jeep Wrangler with the 2.5L 4 cyl. 98,000 miles on it. Stock. I just put a Advance Auto TSP on it and it now runs at 2,000 rpm idle. What could cause this? I noticed the TSP has two ears that fit around a blade on the TB. I thought it could only go on one way. Maybe not!? What can I check? Is there an adjustment?
 
Joined
Nov 22, 2004
Messages
8,701
Location
Texas
Factory original parts are best for items like a TPS. Anyhow, sounds like you may have installed it incorrectly and the ears are holding the throttle body blade open. Try reinstalling it. It is not adjustable like an IAC.
 

Jim Spahr

Thread starter
Joined
Jul 2, 2003
Messages
998
Location
Lexington, SC
I did pull the Throttle Body in order to make it easier to remove the TPS which is jammed up against the firewall. I had no problems getting the TB off. The two Torx T-20 screws holding the TPS on were difficult the entire removal. The aftermarket price was $50.00 which I thought was steep. I wonder what the OEM part would be?
 
Joined
Jun 15, 2003
Messages
36,713
Location
ME
If the torx screw holes are oblongated there's your adjustment. GM is self adjusting every time you start the car, just keep your fool foot off the gas pedal. If you can get the air intake off and see the TB while it's running, you should see the idle air bypass hole. Cover it with your finger, the jeep should idle real low or stall. If this is the case the computer is commanding the high idle. (likely). Otherwise something is hanging the main throttle blade open or you have a vacuum leak. (unlikely) Most new stuff, especially stick shift, hangs the throttle open at around 2000 RPM as a "dashpot" when the TPS signals anything above idle. So your calibration smells off. I guess a battery disconnect wouldn't hurt, in case this helps recalibrate.
 
Joined
Aug 21, 2008
Messages
25,050
Location
ON, Canada eh?
You might try running starting the car without the TPS plugged in. If it idles down then it could be a defective TPS. Does your TB have the Idle Control motor on it? Try taking this off and oiling in between the plunger and the housing of the motor it could be seizing up. (Common on all Chrysler vehicles)
 

Jim Spahr

Thread starter
Joined
Jul 2, 2003
Messages
998
Location
Lexington, SC
Yesterday afternoon when I finished replacing the TPS I cranked it and ran it for 5 or 10 min and it ran great. It just idled at 2k rpm. I tried racing the engine and it always came back to 2k. This morning I cranked it up to go for a drive ( before I redid it)and it idled and drove well. Idled at 800 rpm. Runs well. I guess it recalibrated itself. I also cleaned some minor carbon build up off the insides of the TB. So it is good to go. Tools used are: TORX T-20, 8 mm for air intake, 10 mm for 4 TB bolts. Trick tip: PUll TB to get to the TSP!
 
Joined
Sep 5, 2006
Messages
19,479
Location
Chicago Area
Yes, parameters have to be relearned. It is best to clear the computer when replacing components, but with time it will straighten itself out.
 
Joined
Sep 28, 2002
Messages
39,802
Location
Pottstown, PA
It sounded to me like you had a vacuum leak. The TPS shouldn't be involved until the coolant allows closed loop. Your AIS may have been stuck and freed itself. The same effect would have occurred if you had knocked off a vacuum line off for a prolonged time and then put it back on. The idle would immediately return to normal ..but the recovery and seeking would be awkward for a bit.
 

Jim Spahr

Thread starter
Joined
Jul 2, 2003
Messages
998
Location
Lexington, SC
I am so glad I didn't follow my first inclination to tear into the TPS and see what I did wrong. The lesson learned is to allow any repair that involves engine management technology to be 'relearned or reset' before you redo it. Sometimes just removing the neg. cable on the battery and waiting a few min.s is all it takes. The end of the throttle shaft has a flat blade like a flat blade screwdriver on it. This blade fits into the TPS which has two ears to catch the blade. As the throttle shaft blade turns, it turns the ears and varies the resistance of the Variable POT in the TPS. That tells the PCM the throttle position.
 
Top