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Idle and starting problem.

Osprey413

NAXJA Forum User
Location
Dallas, TX
Ok, so I've got a strange problem that I can't figure out. When my Jeep is cold, and especially when it is wet outside, I have a real hard time getting the Jeep to start. The only way I can get it to start is if the Jeep is at WOT. When it does start the RPM's will sit at about 2000 for a few seconds, then drop down to normal. When the Jeep is still cold, if I give it just a little bit of gas it acts like the engine is bogging down and the engine will die. Then I will have to floor it again to get it to start. Also I've been having trouble with the temperature sensor. It will randomly drop out and go to zero, then after anywhere from a few seconds to a few minutes, the temp sensor will come back and the guage will jump from 0 to 210. While the temp sensor is out the Jeep will run terribly, and bog down with the slightest amout of gas. Then, the other night after I got home from a 2 hour drive, I shut off the engine and went to start it again and I could not get it to run. I could get it to start, but as soon as the RPM's dropped to 1000 the engine would die. I let it sit over night and the next morning I went to start it and it started right up. It was raining that night, and I'm wondering if the water had something to do with it, but then again the engine will have this starting problem. I don't know if this is an IAC problem, or maybe a faulty fuel pump? Or could it all be related to the temp. sensor?
 
It sounds like you got a couple of different problems going on there. The on again off again starting is typical of a CPS going bad. There is a way to check them at the connection for ohms, but its not reliable. I’ve had good ones test bad and bad ones test good. A new CPS will run about $35 at NAPA, Shuck’s, etc. I’d get a new one and swap it out. If it fixes the starting problem, great. If not, keep the old one as a spare in your glove box. They have a nasty habit of dieing at the most inconvenient times and locations. On to the next problem- idle. When my TPS gets wet, it runs like crap. These are pretty easy to check. Do a search for TPS and there will be a list of the procedure and the voltage on the 3 wires. Now the last problem – temp gauge jumping around. Your temperature gauge is connected to a temperature sensor located in the head, on the driver’s side, next to the firewall. It’s a very small sensor, about the diameter of your little finger, and there is a single wire that goes to it. The ONLY thing it does is send a signal to the gauge on your dash. It DOES NOT give any inputs to your computer. The computer gets its temperature signal from the sensor located in the thermostat housing located at the front of the engine. If the gauge is jumping around you have a bad connection, bad ground, or a short. Make sure the wire going to the sensor is seated well and check it for continuity. Make sure that there is at least one grounding strap from you engine to the body/frame. Also make sure that your battery is grounded to the body and the cables are in good shape. If you have a short somewhere in your wiring harness that could definitely make your Jeep run bad. My Jeep would run great when it was cold, but would idle rough and start missing when it reached operating temperature. It turned out to be a combination of the temperature sensor (one in the thermostat housing) and a short in the wires going to it. If nothing else works, it’s worth taking a look at. Good luck.
 
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