capezig

Three times in the last 6 months, two of them recently, we have had trouble with the idle at start up. Each time the van had been running, was off briefly like at a gas station, and then would not idle on restart. Several re-starts and some revving later it runs as it should and we are on the way. No check engine light, so no codes and no other symptoms. Any thoughts appreciated.

capezig

Well...the hard starting issue has not been evident for that last 6 months...and now its back. Today it has happened twice where the van will not idle on restart after it has been running. Letting it sit for an hour or more and it again starts like normal. The 'normal' usually requires a touch of gas pedal to get it going. I have read some forum info that makes me think it might be the camshaft position sensor. Any input would be appreciated. Still no check engine light. Just won't stay running after it is started without keeping your foot in the gas pedal a little.

capezig

Still no progress. Any thoughts here on whether or not this could be an ICM issue with the part of the 'magic box' that controls idle functions failing when hot?

When 'cold' the van will start fine, idle fine, and run forever as long as it is not shut down. If shut down, and attempt to restart while hot, the van will not idle. It will start if you keep a little throttle in it, but not idle. Let it sit for an hour and it will again start and idle as normal.

Makes it kind of tough to drive unless you were trained as an automatic two foot driver.

j.garisto@rogers.com

Had the same problem, took off the IAC unit on the throttle and cleaned out the inside where the plunger seats. Spray carb cleaner and use 4 q-tips at a time to clean out all the carbon build up. Do it many times to clean out the seat so the plunger will close probably on the seat.

chevy47390

Operating according to a variation of the temperature is linked to an electrical fault.
the IAT manages the precision of delay but not to the point of malfunction.
I would be inclined to blame plugs, plugs wires or, ICM (under the candles) they are exposed to the high temperatures of the engine and cause faults without DTC, very difficult to locate; therefore, some change all ignition regularly.
In all cases the default will evolve and will be easier to interpret.

I did not understand if you must wait an hour to restart or if it was possible to drive this bad idle.

The IAM also causes this error, the pipe is generally disconnected or damaged

capezig

This was a spare car, and now I need to get it back together. At the end of the last round I changed the idle air control valve and that seemed to resolve the no idle condition after a hot re-start. Unfortunately, now we are getting a high idle code...I think I got the plunger pushed into the right length as per the install directions. Could the high idle that came along with this be junk in the seat where this plunger is supposed to seat letting air by when it wants to be closing completely? We are also getting a low temp code, and the van never warms up so I am going to replace the thermostat...perhaps this is contributing to the high idle if the magic box does not ever see the engine warm up???

chevy47390

Hello,
I read all the post
We do not know precisely how it does not idle and it is very important
1) is the engine " box" ? rough idle ?
2) the engine stops and cuts like a spark default?

if 1) Power failure when leaving the heating phase so faulty temperature sensor or far away ....

if 2) misfire with the rise in temperature or injection fault
a) check that the ignition is ok. very easy: ground the spark plug and starter
beware of low ignitions

b) check pulses on an injector (500ohms, LED, battery)

I recall that the ignition is completely independent of the PCM. it is controlled by the ICM
The injection time is controlled by the PCM

Best Regards.

this is a google translation! french - english and me

ShortVenture

You say you had a "high idle code" but did the engine seem to idle faster than usual? Occasionally codes get set as a fluke. I usually associate a high idle with a vacuum leak--the oxygen sensor detects too much oxygen and tries to compensate by increasing the fuel. A vacuum leak may also stall the engine at idle. How many miles on the engine? What brand ICV did you use?

Cold Engine: when you start the engine the upper radiator hose should stay cold for awhile until the engine warms up; put your hand on it immediately after starting the engine, if it flows hot water too soon then it could be your thermostat is stuck open. When changing antifreeze use distilled water (89 cents/gallon at the grocery/Walmart) or premixed antifreeze (not tap water) to keep calcium deposits from causing things like the thermostat flapper to stick or fail to close and also plugging up radiator tubes.

I recently had the engine of mine die at idle after filling up with gas so I read your post. Hope my incident was a fluke. Good luck and when you solve your problems please let us know what it was.

capezig

The problem with hot restarts not holding an idle good enough to drive was resolved finally I think by changing the IAC valve. The high idle code was reset and blasted some cleaner in all the holes inside the throttle body and that never came back. I intended to remove the IAC again and clean inside the plunger seat area that way, but the fight with those two little screws just wasn't happening...so everything seemed fine. Now, when I really need it right, the throttle seems to be sticking occasionally. I just drove 1/2 mile down the street at 35 with no foot on the accelerator, and then the idle was very high when I shut it down at the house. On immediate restart the idle was down and normal.
I suppose I am looking at either a bad TPS, bad new IAC, or a mechanical hangup with the cable/plate...any thoughts???

chevy47390

". On immediate restart the idle was down and normal."
The presence of the fault would depend how the butterfly valve is shut down ?

I also think of mismanagement of the intake air, an air leak in the TPS or after the TPS.
difficult to detect a leak after the TPS. close the hose out of the air filter before the MAF, leaving a small hole half or quarter inchesquare. kick off. reduce the hole with the thumb with a glove, slowly, until close. the motor will gradually slow down. If there is a leak must be able to hear and the engine will not stop. If there is no leak the engine will stop .
see if the axis of the TPS is good
whether in the closed position the butterfly valve throttle is really closed.
The Idle Air Control can not work good if all this is not OK. I think that the IAC should never be completely closed.