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Car Forum / Jeep / August 2007Jeep Wrangler High Idle Problem
Hello Everyone: I have a 97 TJ and 95% of the time it idles perfectly. However, about 5% of the time, usually when the vehicle has been run for more than 20 minutes or so, the idle in neutral or park will shoot up to between 1200 and 1500 RPM. The only way to get it to stop is to put the vehicle into gear or to restart the car. If I restart it, it will not happen for a while, but it eventually comes back. The TPS was recently replaced, and I just replaced the idle air control valve, thinking this may have been the problem, but it still has the same effect. I'm thinking now that it may be the coolant temperature sensor (something wacky when the engine is hotter making the vehicle run at higher speeds??). Any suggestions? I'm hoping its not my computer... > Hello Everyone: > [quoted text clipped - 9 lines] > wacky when the engine is hotter making the vehicle run at higher > speeds??). Any suggestions? I'm hoping its not my computer... Does the check engine light come on? Have you checked to see if there are any trouble codes? Jeff DeWitt > > Hello Everyone: > [quoted text clipped - 14 lines] > > Jeff DeWitt Engine light never came on, however I did check codes and this came up when I checked a few weeks ago: 42 An open or shorted condition detected in the auto shutdown relay circuit. An open condition detected in the ASD relay output circuit. An open or shorted condition detected in the fuel pump relay control circuit. An open circuit between PCM and fuel gauge sending unit. Circuit shorted to voltage between PCM and fuel gauge sending unit. No movement of fuel level sender detected. However, I remember seeing that code a few months before this problem came up. I reset the codes a few weeks ago, and the other day I checked and that code hasn't come back. > Hello Everyone: > [quoted text clipped - 9 lines] > wacky when the engine is hotter making the vehicle run at higher > speeds??). Any suggestions? I'm hoping its not my computer... Clean the TPS connector. Go to an electronics parts store and buy some contact cleaner or WD40 works. Disconnect the TPS, clean, connect and disconnect several times, blow dry, then use some dielectric grease on the the connector seal ring to keep moisture out.  SignatureWill Honea >> Hello Everyone: >> [quoted text clipped - 14 lines] > disconnect several times, blow dry, then use some dielectric grease on the > the connector seal ring to keep moisture out. Yup, replacing parts only cleans 'half' the connection. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) How would the TPS affect idle speed? From my understanding, it is just a sending unit, meaning it can only give information to the PCM but cannot receive and therefore manipulate any settings. > >> Hello Everyone: > [quoted text clipped - 23 lines] > Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590 > (More Off Road album links at bottom of the view page) The PCM uses the signals it receives from the TPS to adjust other systems on the engine. I would also recommend cleaning the IAC valve and connector. If it is sticking it can raise the idle speed up. > How would the TPS affect idle speed? From my understanding, it is just > a sending unit, meaning it can only give information to the PCM but [quoted text clipped - 24 lines] >> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590 >> (More Off Road album links at bottom of the view page) The TPS is a resistance based switch just like a volume control. You can even test it with a multimeter set on ohms or live with the meter set on volts. If it has a bad connection, this connection has a resistance factor that isn't supposed to be there or an arcing issue which causes surges. When ours got a dirty connection, it would usually stall at the first stop and get stuck on a 1500 to 2000 rpm fast idle. We were told back in the 90's that we needed a new TPS in our Cherokee, We just retired the Cherokee recently with that same 'dead' TPS in it.... All the computer sensors are very low power items that are very touchy about their connections. A spray can of electronic contact cleaner will be a very good friend to you as the Jeep gets older. It will sure save you money, because changing out parts only fixes 'half' the connection... Mike > How would the TPS affect idle speed? From my understanding, it is just > a sending unit, meaning it can only give information to the PCM but [quoted text clipped - 24 lines] >> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590 >> (More Off Road album links at bottom of the view page) > The TPS is a resistance based switch just like a volume control. You > can even test it with a multimeter set on ohms or live with the meter [quoted text clipped - 47 lines] > > - Show quoted text - The best contact cleaner stuff is DeoxIT, www.deoxit.com You can get it at RadioShack, Fry's and other electronic stores: http://store.caig.com/s.nl/sc.15/category.295/.f Work's everytime for me. Mike The Wrangler was in high idle today so I decided to investigate. I disconnected the TPS Sensor and the idle went back down to its normal RPMs. I then reconnected it and the RPMs went back up. Tried cleaning contacts, not help there. Perhaps the TPS is defective? It's still under warranty so I can just bring it back. Mike > The TPS is a resistance based switch just like a volume control. You > can even test it with a multimeter set on ohms or live with the meter [quoted text clipped - 45 lines] > >> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590 > >> (More Off Road album links at bottom of the view page) You can do a voltage test on it. If you have the AC off and the key just in 'run' with the engine off and back probe the TPS plug with multimeter probes set to volts, it should be at .02 volts at idle and 4.8 volts at wide open. Mike > The Wrangler was in high idle today so I decided to investigate. I > disconnected the TPS Sensor and the idle went back down to its normal [quoted text clipped - 51 lines] >>>> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590 >>>> (More Off Road album links at bottom of the view page) AC? I have a JEEP remember?!?!?!? jk thanks for the specs I'll test it tomorrow. One question...there are 3 terminals, which ones do I hook up the multimeter to? > You can do a voltage test on it. > [quoted text clipped - 59 lines] > >>>> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590 > >>>> (More Off Road album links at bottom of the view page) >AC? I have a JEEP remember?!?!?!? jk thanks for the specs I'll test it >tomorrow. One question...there are 3 terminals, which ones do I hook >up the multimeter to? One of them should be a ground, one of them's a 5v reference voltage that won't change and the other one should vary between the values Mike gave you as you move the throttle. -- Old Crow "Yol Bolsun!" '82 FLTC-P "Miss Pearl" '95 YJ Rio Grande BS#133, SENS, TOMKAT, MAMBM SignaturePosted via a free Usenet account from http://www.teranews.com ok tested. closed: .938v open: 3.9v defective TPS? > You can do a voltage test on it. > [quoted text clipped - 59 lines] > >>>> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590 > >>>> (More Off Road album links at bottom of the view page) Sure sounds like it. The idle reading it high. Mike > ok tested. > closed: .938v [quoted text clipped - 57 lines] >>>>>> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590 >>>>>> (More Off Road album links at bottom of the view page) > Sure sounds like it. The idle reading it high. Throttle closed > 200 milliVolts Throttle wide open < 4.8 Volts Anything in that range will adjust. The way you 3.9 is low as well. Measure the outer two pins to make sure your getting close to 5V. Before getting a new one, run the old one back and forth a few dozen times with the engine off, then measure again. Also make sure the connector is clean and free of crudbunnies. >> ok tested. >> closed: .938v >> open: 3.9v >> >> defective TPS? |
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