very slight rough idle

[four_by_ken]

M1009. It runs good, starts very easy, etc.

But, at idle (even when warmed up)... there is a little roughness that comes and goes. Well, it always does it... but it is not constant.

Sitting at stop lights is when I notice it the most. Cant remember if I notice it when it is in park or not. Its a stumble every few seconds.

Any ideas?

 

[jakwi]

You know mine does a similar thing at idle, but it's less a stumble and more a variation in idle speed, anywhere from 50 to 200 rpm. I think my problem is an air leak in the stock fuel filter housing, maybe you are having the same problem. You might try bleeding your injectors out and see if the problem goes away temporarily. When I bleed mine out the problem goes away for a couple of days.

M1009. It runs good, starts very easy, etc.

But, at idle (even when warmed up)... there is a little roughness that comes and goes. Well, it always does it... but it is not constant.

Sitting at stop lights is when I notice it the most. Cant remember if I notice it when it is in park or not. Its a stumble every few seconds.

Any ideas?

 

[Buckmaw]

When you say "rough idle", are you saying there is a vibration in the truck at idle?

If so, check your motor mounts.

 

[four_by_ken]

Its a slight cough... a hiccup every little bit. Then smooth... the a little hiccup. Definitely not motor mounts.

 

[2deuce]

Mine does the same thing, a rough idle. I tried a new cdr valve... its still rough. I increased the idle alittle and its better but still rough. Mine accelerates smooth off the idle. I wondered if the IP was getting weak and shows up at idle. I've put 25k on my truck and its always been rough, so I'm interested in the solution. Another symptom my truck started doing in the last 1k is changing speeds at freeway speeds. It will start accelerating slightly on its own to where it seems to be hunting, it won't stay steady like it used to. Coupled with the rough idle makes me think the IP is losing it, but I don't know. Hopfully the experts can help.

Thanks,
Greg

 

[four_by_ken]

I only have the idle cough. Accelerates fine... cruises fine... just at idle. Fuel filter is brand new.

 

[2deuce]

Mine is rough only at idle also. accelerates smooth and runs smooth at freeway speeds, just wants to accelerate on it own slightly at times and that came up only recently. The last symptom I added because I wondered if both things could be due to the IP. How long has yours been doing the rough idle? The timing was retarded on mine when I got it. It was very quiet. I set the timing marks but the rough idle didn't change, but it did get noisier.

Greg

 

[four_by_ken]

I have only had mine since the end of January. Put about 800 miles on it. Has done it ever since I got it.

 

[2deuce]

Seems to me if it was an air leak it would give us a hiccup other than just at idle, but maybe the fact that mine wants to fluxuate at freeway speeds is also a sign that the problem is getting worse and if so yours might too. Maybe the freeway accelerating glitch is a sign of air, I don't know. Mine has been giving me the rough idle since I got it about 2 years ago. When I moved the timing marks to align, there was a slight increase in power, but the hiccup persisted.

Greg

 

[Mudstone]

i donno what my truck is doing... it runs feels powerful the mounts are good as is the balancer... but my whole **** truck shakes when that 6.2 idles. frankly... i kinda like it.

 

[2deuce]

One thing I forgot to add is that the fast idle/retard on the IP doesn't work on my truck. The truck starts easily with just a touch of throttle and runs smooth if you get it a tiny ammount of throttle until the glow plug end their cycle. I'm thinking of replacing this part to see if can have any effect on the truck when warm. I didn't think it would but who knows. Anyone have the part #? Can you get it at napa?

Thanks

 

[2deuce]

Has anyone found the cause of the rough idle? Last weekend the rough idle got alot rougher all of a sudden and has stayed that way. With alittle throttle it cleans up and runs smooth at all speeds, but at idle it shakes alot more than it used to. Its a random miss that visibly shakes the truck, but step on the throttle and it accelerates smooth.

Thanks,
Greg

 

[four_by_ken]

Mine is till doing it... no change what so ever.

 

[2deuce]

It was annoying before, now its concerning. I'm wondering if its an injector symptom.

 

[2deuce]

Ken,
I removed the green wires from the ip. Mine now idles smooth. I'll see what the difference that makes during a cold start. Curious if that helps yours.
Greg

 

[four_by_ken]

Ken,
I removed the green wires from the ip. Mine now idles smooth. I'll see what the difference that makes during a cold start. Curious if that helps yours.
Greg

Whats the green wire supposed to be for?

 

[lavarok]

Cold advance solenoid

 

[2deuce]

When I removed the cold advance and fast idle wires, it idled smooth. Today the slight roughness returned but the very rough rumping idle hasn't and the speed changing hasn't returned either. Starting was alittle more difficult but not much. It was about 45* today.

Greg

 

[four_by_ken]

When I removed the cold advance and fast idle wires, it idled smooth. Today the slight roughness returned but the very rough rumping idle hasn't and the speed changing hasn't returned either. Starting was alittle more difficult but not much. It was about 45* today.

Greg

I may disconnect as a test, but living in MI, I dont think I want to do anything that may add difficulty to starting in the winter.

 

[2deuce]

Possibly try it when the truck is warm. I'm thinking that the problem is somewhere in the fuel delivery, possibly dirty injectors and my electrical glitch compounded the problem. I can live with it the way it is, but not the way it was.

Greg