Sticky idle

[NUKEMAN]

Lately my idle has been sticking at 1000 rpm about 80% of the time. Happens in cold or warm weather. If I let the clutch out as if I'm taking off, it drops down to normal. If I mash the brakes, that also drops it back down. No other symptoms; any ideas?

 

[nickleinonen]

just a shot in the dark...



intake air temp sensor defective maybe. . reading too low. . mine will idle up right from start when it gets below -4°c, but if i put the brake on, it will come back down [unless it is like -15°c, then it will stay up until moving]



reason i am thinking iat instead of coolant temp sensor, my truck will idle up with a warm engine when left sitting for a while, when it is cold outside [>-10°c]



see if you can find a scan tool that will read the obd port while running, and see what the iat is reading compared to actual ambient temp. .



maybe it could be a poor connection too? check the baro/iat sensor connection on the air intake tube [after air cleaner before turbo inlet]



$0. 02

 

[Prairie Dog]

If your in extremely cold weather it will idle up even after the eng has warmed up. Has something to do with keeping combustion temps up for emmisions reasons.

I think your truck is working normally.

 

[NUKEMAN]

The reason why I think it is abnormal is because it just started doing it within the last 3 months. Even if the engine is at operating temp, it still happens. Just curious if it is a reflash thing or not.

 

[Prairie Dog]

Like I said, will do this if the combustion temps are too low - even if the eng is totally warmed up.

Mine has done it on single digit days arround here. What are the temps in your area?

 

[NUKEMAN]

Anything from -30 to +60 any day of the week. Crazy weather up here.

 

[grasshopper1]

My 03 does the same thing, summer or winter. I was wondering if your trucks RPM's stay at 1000 RPM's while shifting.

 

[Slow Six]

I had that same problem with mine. After a couple of visits to a "good" dealer and a couple of calls to DC by the mechanic it was determined that the connections in the block that goes onto the ECM was defective as they were not sized properly. The story I got is that there was a change in manufacturers of this part. The right connectors were ordered and installed and it has idled properly ever since. I could also lock the doors with the switch on the door with it open and the engine running and also had erratic engine fan operations. This fixed all the problems. The only PO of this is that even though DC acknowledged a defect it was my nickle as I was just out of warranty. They would not even consider any good will. My truck is not the only one that this dealer has had the same problem with. Also my truck was an early 03 built in 02.

 

[Pawpaw]

Anything from -30 to +60 any day of the week. Crazy weather up here.

The engine is supposed to go into fast idle if the intake air temp falls below 66 degrees.



Bob

 

[Slow Six]

The problem is not high idle due to cold. This 1000 RPM idle happens intermittently, such as when you come to a stop and disengage the clutch. If you let the clutch out just enough to put a slight load on the engine, the idle drops down to where it is supposed to be. Also sometimes if you rev the engine up and get off the go pedal the idle will hang up at the 1000 RPM. As Nukeman stated, his is about 80% of the time which is pretty well the way mine was before it was fixed.

 

[NUKEMAN]

The problem is not high idle due to cold. This 1000 RPM idle happens intermittently, such as when you come to a stop and disengage the clutch. If you let the clutch out just enough to put a slight load on the engine, the idle drops down to where it is supposed to be. Also sometimes if you rev the engine up and get off the go pedal the idle will hang up at the 1000 RPM. As Nukeman stated, his is about 80% of the time which is pretty well the way mine was before it was fixed.

Amen. Nail on the head.

 

[NUKEMAN]

I had that same problem with mine. After a couple of visits to a "good" dealer and a couple of calls to DC by the mechanic it was determined that the connections in the block that goes onto the ECM was defective as they were not sized properly. The story I got is that there was a change in manufacturers of this part. The right connectors were ordered and installed and it has idled properly ever since. I could also lock the doors with the switch on the door with it open and the engine running and also had erratic engine fan operations. This fixed all the problems. The only PO of this is that even though DC acknowledged a defect it was my nickle as I was just out of warranty. They would not even consider any good will. My truck is not the only one that this dealer has had the same problem with. Also my truck was an early 03 built in 02.

Wow, I never even tied the erratic fan and door lock issues to this. This is making complete sense now. How much was the repair if you don't mind me asking.

 

[Slow Six]

I got hit for about $1400. 00. The new connector blocks are expensive plus labor. They took about 10 hours to do the work which I think was a bit to long. To be fair though, it is a time consuming task. There is close to 80 wires that have to be cut and spliced with each connection soldered and heat shrinked plus being certain there are no screw ups. It is also in an akward and uncomfortable place to work. Like you I was surprised that all these functions were affected by the ECM. I was tempted to just live with the situation but I tend to keep my trucks longer than most plus I like everything to be operating properly and the chance that it may have led to more serious problems down the road.

 

[jman]

Mine has been doing this for a while also. Same thing, come up on a stop sign and it is stuck at 1000 rpm, put it in gear and ease out on the clutch and it returns to normal idle. I can get mine to quit with the brake if I put a lot of pressure on it, but sometimes that doesn't even work. It has been in the 70's here for a while so it isn't the cold temperature idle up we see in the winter months. At times I can use the accelerator pedal to increase speed to 1000, let off and it will stay until I let out on the clutch. I guess I should get it in one of these days. I have 87K on it now so I still have a few miles left.

 

[SKing]

WOW my 03 has done this for a while. . Good to know what the fix is. I will go get the part and rewire it. This is the same type of problem thats in the ignition plug and harness. Wires are to small. I wonder if its just early model 03s that have this problem. I bought my 03 in Nov 02. The temperatures that I have had to drive in are in the 80s to low 90s and I have the same problem so It sounds like its not a temp sensor. Thanks for the info it was as helpfull as the post of pictures about how to fix the defrost doors. I fixed my door actuators myself thanks to that. Now I get to play wires. :-laf

 

[Semicrazy]

Mine is an early 03 and it is doing the same thing. It just happens out of the blue anytime and it does not matter if I am pushing in the clutch or coming to a stop. But it has not been above 70 here yet, so I will wait a few weeks to see if the issue gets any better. If not, may have to set aside a day for rewiring... :{

 

[jman]

Mine hasn't been starting the best when cold and this all happened around the same time. There is no use waiting for the grid heaters cause it is going to start lousy anyway. I know the grids are working too because the Volt gauge moves as they cycle. Similar symptoms involve the rail pressure relief valve. Has anyone tried this? If I hit the throttle when idling it goes up normally, but returns to 750 rpm very slowly. I need to get it in and see if they can fix it before I run out of warranty. Luckily I have a good dealer so maybe I have a chance.

 

[jman]

Just picked mine up from the dealer today and I mentioned this to them. They said they couldn't get it to do it so I went down and got it warmed up and tapped the throttle and of course it wouldn't stick, but it would take about 3-5 seconds to idle down from 1000 rpm. The advisor told the "Tech" and he said I was confusing it because it has 2 APPS sensors and tapping the throttle confuses it. I'm not buying this confusion bit because it wasn't "confused" the first 78K miles I owned it. It became "confused" the last 20K miles. It is supposed to be in the 40's for lows early this week and it is way worse when it is cold so we'll see if I can get it to act up and take it in.



On the positive side I got new upper and lower ball joints at 98. 6K under the extended warranty. That is pretty good timing in my book.