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-   -   IAC or TPS? (http://www.wranglerforum.com/f282/iac-or-tps-17659.html)

nater344 04-15-2008 07:30 AM

IAC or TPS?
 
I have done several searches and have still not come up with an answer to what my problem is.

I have a 97 SE that will idle well most of the time (cold or warm), but occationally sputters down to about 500 RPM, then catches and goes up to about 2000 RPM. From there it goes back and forth and does not idle well, almost stalling out. I have already replaced the plugs, wires, distributer cap, rotor and air filter. I then removed the throttle body and IAC valve and cleaned them well, including the connections to the IAC and TPS, both of which received some dielectric grease. After putting on a new throttle body gasket and reinstalling everything my Jeep runs worse. Now it sputters most of the time at idle. The only code that it is showing is a 21 which I believe has to do with one of the O2 sensors.

My question is, what part should I start with? The IAC or TPS?

Your help will be greatly appreciated.

nater344 04-15-2008 12:56 PM

Anyone?

Jerry Bransford 04-15-2008 01:15 PM

If you thoroughly cleaned the IAC's solenoid-actuated plunger, and you also throughly cleaned the oriface (hole) in the throttle body the IAC's plunger fits into, then it's just about guaranteed the TPS is the culprit.

nater344 04-15-2008 01:33 PM

Thanks Jerry. I scrubbed the entire throttle body inside and out and the IAC plunger and the problem is worse. I will go ahead and replace the TPS. Thanks for your help.

Jerry Bransford 04-15-2008 01:41 PM

One thing else to try that might help solidify the TPS as the culprit... fully cycle the throttle 50-100 times which will work the TPS's internal electrical connection back and forth. If the symptoms change especially if they seem to improve, then odds are even better that it's the TPS. This action moves the TPS's electrical contact back & forth along a carbon "resistor" which can sometimes temporarily clean it up a tad so its electrical output is not as eratic. This output tells the computer what you're doing with the accelerator pedal so if it's eratic, it's just like your foot was eratic on the pedal. :)

Gerald 04-20-2008 08:48 AM

Hi,
I have just had a very similar problem, my idle was up and down and for no apparent reason either, after a month of looking and checking and fitting new parts I finally got to the bottom of it. Turned out to be the TPS was not as tight as it could be, so the value on the throttle was never the same level, some times would read 1%, sometimes 3% and then other times would read 0 at idle. Tightened the TPS and problem solved! If the tps is reading slightly open it affects the IAC as well.
Hope this helps.
Gerald

nater344 04-21-2008 10:05 AM

I replaced the TPS and the problem is still there. It is at the dealership today for 2 recalls, so I will know a little more after they plug it in. I know that it is throwing an O2 sensor code, but I'm not sure which one. After I replace the bad O2 sensor, I'll move on to the IAC and see what happens. Thanks for your help.

nater344 04-23-2008 09:34 AM

Just to let everyone know the dealership replaced the catalytic converter and the downstream O2 sensor and cleared the check engine codes. On may way home the jeep threw an O2 sensor code and started stalling out again. I went to the auto parts store, picked up an upstream O2 sensor and installed it. Well that was my problem all along. The upsteam O2 sensor must have been making the Jeep run rich, thus causing the jeep to sputter and stall out. I have driven it about 30 miles (5 of which were off-road) and no sputtering and no check engine lights. Thanks for everyones help and make sure that you call your dealership and make sure you don't have any outstanding recalls. Just for calling I got a new fuel sending unit, catalytic converter and O2 sensor. Can't beat that!


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