I hope this was the culprit...
Super Moderator
Joined: Jul 2007
Posts: 13,098
From: Boat Town USA MI
Looks pretty normal to me. It is the fuel management system that is taking the idle rpm as low as it can to run all needed accessories with no unwanted additional fuel expenditure and its millisecond lag time to adjust once it finds that spot. That idle amount would be different with the AC on or off, if you had the heater, windshield defroster, rear defroster, wipers, radio, headlights and foot on the brake all at a stop sign, the amount of fuel to get to the lowest possible idle for that situation would be different as well. The fuel management system inputs the AC clutch and alternator load to output needed, then adjusts on the fly to aim for the lowest idle possible when the vehicle is stopped.
A sticky TB (dirt or film, etc...) can contribute to make that seem worse as the PCM may over/under correct the throttle location while looking for that low idle spot. Some people complain their headlights may dim for a second at a stop sign or stop & go traffic and think that is wrong, but it is just the delay in fuel management execution.
The key is, your truck does not stall. The PCM is doing what it was programmed to do.
A sticky TB (dirt or film, etc...) can contribute to make that seem worse as the PCM may over/under correct the throttle location while looking for that low idle spot. Some people complain their headlights may dim for a second at a stop sign or stop & go traffic and think that is wrong, but it is just the delay in fuel management execution.
The key is, your truck does not stall. The PCM is doing what it was programmed to do.
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Member
Joined: Jul 2018
Posts: 85
From: Phoenix, AZ
I appreciate the responses guys! Sadly my truck continues to stall usually when going over a speed bump or just coming to a stop 
I’ll try a few more things, I’ve already cleaned the sensor and intake.
I’ll try a few more things, I’ve already cleaned the sensor and intake.
Thread Starter
|
Member
Joined: Jul 2018
Posts: 85
From: Phoenix, AZ
Looks pretty normal to me. It is the fuel management system that is taking the idle rpm as low as it can to run all needed accessories with no unwanted additional fuel expenditure and its millisecond lag time to adjust once it finds that spot. That idle amount would be different with the AC on or off, if you had the heater, windshield defroster, rear defroster, wipers, radio, headlights and foot on the brake all at a stop sign, the amount of fuel to get to the lowest possible idle for that situation would be different as well. The fuel management system inputs the AC clutch and alternator load to output needed, then adjusts on the fly to aim for the lowest idle possible when the vehicle is stopped.
A sticky TB (dirt or film, etc...) can contribute to make that seem worse as the PCM may over/under correct the throttle location while looking for that low idle spot. Some people complain their headlights may dim for a second at a stop sign or stop & go traffic and think that is wrong, but it is just the delay in fuel management execution.
The key is, your truck does not stall. The PCM is doing what it was programmed to do.
A sticky TB (dirt or film, etc...) can contribute to make that seem worse as the PCM may over/under correct the throttle location while looking for that low idle spot. Some people complain their headlights may dim for a second at a stop sign or stop & go traffic and think that is wrong, but it is just the delay in fuel management execution.
The key is, your truck does not stall. The PCM is doing what it was programmed to do.
Still having issues, throttle will go way up, then drop way down almost stall, way back up, then back down then up again...usually that happens when started. Crazy sh$t! On the road will die at low speeds, and a couple of times stutters going down the road! list of everything I’ve done to date
MAF sensor- Cleaned and returned to service
TB
Crannkcase sensor- Looked good according to what I’ve read on here, wiped off and returned to service
Spark Plugs- Replaced
Air Filter- replaced
Techron 2 bottles so far used according to directions (tank almost at empty when applied etc..)
intake bolts are tight.
i dont know, fuel filter maybe, need help thanks
Senior Member
Joined: Jul 2013
Posts: 592
From: Virginia
Have you tried compression or leak down test to see if you have a valve problem? That caused my rough idle and it was not throwing any codes or CEL, just really rough at idle. Re-machined valves fixed the issue.
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Member
Joined: Jul 2018
Posts: 85
From: Phoenix, AZ
That’s probably The next thing I’m going to do. My aftermarket warranty kicks in in three days. I’m going to take it to the dealership, and less somebody else knows a good H3 mechanic in Phoenix. I’ve often wondered if there was an internal engine issue. I bought mine at auction, it was up for sale at Bill Luke Chevrolet for one day and then sent to the auction which is suspicious. The whole reason I bought the aftermarket warranty in the first place. I can say it does run a heck of a lot better since I did all of this maintenance though.
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