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high idle when slowing down


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hey guys, been having a lot of issues with the jeep recently, replaced the alternator, it was throwing a code, that issue is fixed. However, right after I replaced it, it threw a coolant temp sensor code, replaced that and I'm still having issues. When I drive, say I accelerate up to 25 mph or so, when slowing down, my idle still stays high until I come to a complete stop.. this can't be normal right?

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hey, think i fixed the problem just in case anyone ever has this issue... So here's the whole story.. Yesterday on my way home from work, the check engine light came on, so when I got home, I read the codes and I had a 12, 33, 41, and 17. 12 and 33 aren't an issue but 41 has to with the alternator, so i had it tested and sure enough, it was going out on me. 17 has to do with the thermostat. So I bought a new alternator and thermostat. When I put the new alternator on, the 17 code disappered, but it changed into a "22" so I took the thermostat back and bought a coolant temp sensor. Installed it in the parking lot and on the way home I felt the idle was WAYY too high when I was in neutral. So I figured it was the IAC valve, took that off cleaned it up, cleaned the TB while I was at it. Didn't fix my issue. Actually my issue worsened.. My truck wouldn't start.. I was thrown for a loop. I figured it had to be the the TPS or IAC at this point.. HAS to be right? Before I went and bought a new tps and iac, I figured I'd give a shot in the dark and reset my ECU.. Whatever it did, my truck is running good again. I'm guessing when installing new sensors, you want to make sure you have to battery disconnected, or reset it directly after a fresh installment. Hope this helps someone..

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4 minutes ago, Ωhm said:

Two hour story with a good ending.

dude, you have no idea, i thought I was gonna have to carpool to work tomorrow.. and that means I wouldn't have any of my tools or anything.. would have been rough. 

where there is a will, there is a way lmao

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36 minutes ago, HOrnbrod said:

 

How did you reset it?

I'm assuming thats what I did, but basically I disconnected the positive wires on the battery, grounded them to a reliable ground wire for 30 seconds. After that, I reconnected the positive wires to the battery. Got in the truck, turned the key on (but didn't start the vehicle). Turned my headlights on, turned the headlights off, then turned the key off. Waited 10 seconds or so, started the truck and everything worked like a charm after that.

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You must have read that somewhere, like here? That's the correct procedure for the Jeep 4.0 and 2.5 OBD1's to reset the ECU/PCM back to the original unmodified factory settings and remove all residual memory. For a stock engine it should be done whenever you change a sensor to clear a fault code. You done good!

 

https://comancheclub.com/topic/53413-check-engine-light-blink-codes/?tab=comments#comment-544969

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