QuestionMy '96 2.5 V6 is having a problem idling. I can start the car and it seems like its running okay but when the tach drops to 750, 500 rpms or so, the engine dies. Occasionally it will stall in traffic at a light or in a traffic jam. Usually once it gets going it's fine. I thought I had the problem solved after replacing PCM, egr valve, idle speed motor, throttle position sensor. But several months later, the problem is back. A dealer's mechanic is suggesting there is an electrical short, which I find it hard to believe. Sounds like an excuse to chalk up some lucrative troubleshooting time. Would appreciate your comments.
AnswerOne last possibility is that the coolant temp sensor is off calibration. It should read 7-13K ohms when at 70F and 700 to 1k ohms when at 200F. It is located near the coolant filler tube. It wasn't clear to me if your problem is mainly during warm up, or at all engine temps.
Hi Gene,
It appears you have gone to some lengths to resolve this problem, so we need to consider alternatives. I suspect you know about reading out fault codes but just in case:
Try using the ignition key: turn it "on-off-on-off-on" and leave it "on" (doing this quickly, no longer than 5 seconds). By "on" I mean just the normal position when the engine is running, not the cranking position. The 'check engine'light will remain on when you leave the key in the "on" position with the engine still not running. But then watch the 'check engine' light to begin flashing, then pause, flashing, pause, etc. Count the number of flashes before each pause and keep track of the numbers. Repeat the readout and verify the counts are correct. Then group them in pairs in the order that they came out, thus forming two digit numbers. You may notice that the pause is shorter between the digits of a given number, and longer between the numbers themselves. Then send me a 'follow-up' question telling me the results of your readout. By the way, 55 will be the last number (two groups of 5 flashes each) and that is the code for "end of readout".
If nothing remarkable emerges from that then I would begin to look as follows:
a vacuum leak (follow the hose diagram on the underhood sticker as a road map looking for a cracked or disconnected hose associated with the intake manifold), or the throttle body might be loose,
the pcv valve maybe stuck and need replacement,
the air filter maybe clogged,
the fuel pressure maybe off (should be 49 +/- 2 psi),
check the ground straps for good connection at both ends,
check the engine vacuum reading,
check the calibration of the MAP sensor,
check the minimum idle air flow,
check the timing, and inspect the spark plugs.
This is a troublingly long list of possibilities, unfortunately. But you may be able to dismiss several based on whether they have been checked/serviced recently. Let me know if one of them seems particularly relevant but you need more specifics to check it out.
I would appreciate knowing what it was after you find out!
Roland
