QuestionQUESTION: On my 2001 Dodge Durango 4.7L 4x4 I lost the cold idle after removing and cleaning the trottle body, IAC, TPS, MAP, IAT, ECT and resetting the computer by disconnecting the battery and having the key in the on position.
Once it warms up, everything is fine. Good smooth idle, great vaccum, no problem, just when it's cold in the morning it starts right up but NO higher fast cold idle like it use to before I cleaned and replaced the parts I mentioned. I live in a very cold climate so I need the cold idle.
I even tried another IAC thinking the first one was bad but no change.
No engine light is showing and mileage and acceleration is good. I was thinking maybe a PCM problem?
Any advice would be greatly appreciated.
Thank you.
ANSWER: Hi David,
I would seek a fault code readout using a plug-in code reader. Let me know any 4-digit numbers you get and we can go from there. I am not expert in that engine, but if the code is clear we can probably figure out what to do. A nationwide parts store will often do that for free. Try the ignition key:on-off-on-off-on and leave on, doing that in 5 seconds or less elapsed time. Then see if any 4 digit number show up in the odometer window of the cluster. If not, then a plug-in readout is the only way to get codes.
Roland
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QUESTION: Roland,
I just finished trying your suggestions and unfortunately because the check engine light is not on the scanner found no codes and I didn't see anything in the odometer after trying your on-off 3x in 5 sec.
At this point, I really don't know what to do.
Thanks,
David
ANSWER: Hi David,
Poor cold idle with no codes is tough. Does the engine have an egr valve? If so I would check to see that the valve stem is moving freely and closing to a dead stop. If it were hung up slightly ajar that would thin the mixture too much for a good cold idle, and then when it warms up it might loosen up and close normally. Other than that, a subtle off-accurate on one of the sensors, but not so bad as to set a code, might explain the problem. But that requires a readout with a diagnostic box that gives settings of all the sensors.
Roland
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QUESTION: Roland,
There is no egr valve.
The only unusual thing I have noticed is that now upon removal of the IAC motor the position of the piston is out quite a ways more than when I installed it.
The position of the IAC motor piston/mandrel was about 1 1/8" out when install and upon removal is at about 1 3/8" distance out. It seems as if it doesn't move back in?
Does this readout with a diagnostic box that gives settings of all the sensors tell one about the IAC positions and or if pcm working properly?
Tbanks,
David
AnswerThe AIS motor is positioned by the pcm, based upon the ambient (engine/environment) conditions, so is not surprising that it has moved. The readout box should show the position of the piston, and how it changes as the engine warms. It is shown as 'step' positions. There is a fault code for a faulty pcm.
