My 2002 "Lopey Idle" Finally Fixed

[Livin2DMax]

I had this problem since Oct 2001 (about 1mo after I picked up the truck). Truck has roughly 8000 miles on it. The truck idle would lope from cold until about 185F. Always cleared up when engine temp went above 185F. I had it looked at multiple times with no fix. "It's normal" or "it's the fuel" or "it's a diesel" or "waiting for GM to solve it". Got the impression that the dealer and others thought I was just too picky. When the warmer weather hit I noticed it smoking a little. Could have been smoking in the colder temps but I didn't notice it and obviously the dealer didn't either. Sometimes when I threw it into park or neutral at idle it would stop loping and smoking. I'd put it back into gear at idle....loped and smoked again. Tried different fuels, new fuel filter...etc etc. Last week I decided I had had enough and took it in again. Mentioned to the dealer....how about the fuel regulator...or an injector? He said "you been surfing the internet again?". First I got the latest 2002 software upgrades...with another "all ok" from the dealer but it loped on the way home. I can handle a response like "let us know if this works or not" but when you say "all ok" I expect it to be @#$%#@ fixed! Took it back again (and started looking into the lemon law). The tech dug a little deeper into his bag of tricks this time (or maybe he started surfing the internet) and with some help from GM found that injector #1 was bad and replaced it. It's been a week now and I'm willing to say that it's really "all ok" now. I have zero lope....cold or warm air temps....cold or warm engine temps. Idles like a champ and no smoke.

Can anybody explain the connection between my cold engine temp and injector failure? Official text on the work order reads:

"...checked fuel reading, noticed #1 injector balancing rate at 12.5mm cubed about 12-14mm cubed over other injectors. First checked compression and was ok at 320psi (280psi min). Then replaced #1 injector...all ok."

Now.....just the tick-tick-tick remains between me and 40k+ of diesel perfection. I think I'll cut myself a break though and crank up the stereo for a while.

[ 05-14-2002: Message edited by: Livin2DMax ]</p>

[DmaxMaverick]

Livin2DMax

The hot/cold issue could have been the temp/viscosity of the fuel affecting the injector function.

To date, my dealer has replaced 3 injectors (At the same time. 2 on one side, one on the other. What a PITA). My complaint was the lopey idle and a RPM driven knock (not the tick. been there, done that). Sounds like a rod, but is fuel related. It is worse when cold. It started at about 30K miles around last Christmas.

Now, the knock and lope is worse, and mileage is declining fast. Either they replaced the wrong injectors, or the problem lies elsewhere. I did also find the downpipe bracket was broken (stress crack). Part on order. I'm sure I'll be camping out at the dealer for a while in my near future. I'm driving it now with no real problems. Still has power and runs well, other than the noise and lope. Guess I'll just drive it until it blows. I'll just have to settle for a new motor. This one has 40K on it. Even with the current problem, I don't have any real complaints with the truck. Gotta love it!

[srubrn]

lIVIN2DMAX,

What did you use to discover the bad injector? My dealer/ sevice manager could not find any thing about the injectors on his tech II. Maybe he doesn't know where to look. Clue me in!!

[Livin2DMax]

DmaxMaverick,
That seems to make sense. Didn't think about the fuel viscosity changing that much. So far the truck is running great so I hope it's only the one injector. We're 5th wheel shopping so I wanted to get this issue fixed before I started towing something heavy. I'm real happy with the truck also especially now that it idles properly. Seems to have a bit more "pep" too. Since your problems started at 30k are you covered under warranty with all these fixes? Good luck. Hope they fix your problems.

srubrn,
This is my first diesel so other than persistence and trying to get the dealer to listen to the tips I was feeding them from this forum I didn't have much to do with discovering the bad injector. And my service dept. is not big on giving detailed descriptions. Like others have posted here, dealer mentality is often "we are the experts and like to find the problem ourselves". If they fix my truck when I need it then I guess I can live with that although I like to know more. I think after a number of visits the tech finally found there was a bona-fide problem. He then called GM for help in isolating it. Service writer hinted that this is the first of this type of problem they've dealt with. If you want I can send you names and numbers at my service dept. I think they'd be willing to help out if they could.

[JLee]

I hate to be dense, but what, exactly, does "lopey" idle feel like? Mine seems to "hesitate" on acceleration when cold, but I'm not sure I'm getting the same thing.

Thanks

Jim

[Livin2DMax]

Jim,
If I was idling in gear with my foot on the brake I could feel the truck trying to pull or surge forward. If I was idling in park it seemed like a slower frequency idle like it was fighting to stay alive. I've seen the term idle surge used as well. I haven't actually heard sound clips of any other trucks with lopey idle but the forum descriptions sounded similar so I adopted it. GM had heard the term before when I talked with them. I hope this helps. Sorry but I can no longer capture and send you a lopey idle sound bite. smile.gif

PS
Mine never hesitated on acceleration.

[ 05-16-2002: Message edited by: Livin2DMax ]</p>

[JLee]

Thanks Livin - mine doesn't seem to do that. I was particularly interested because folks seem to realize an increase in MPG when they get it fixed. Thought if I had the problem maybe my mileage would get better. I've not been happy with my MPG at 14.8 or so, mostly driving in town but not a lot of real heavy stop 'n go. I only have 3000 miles on it, hope it improves.

Jim

[Livin2DMax]

Your welcome Jim. Some folks with similar symptoms have had different problems/fixes than mine. I'm not sure whether I should expect a mileage increase or not with mine. I haven't gone through enough tanks of fuel yet since to say there was a definite change. I would have actually given up fuel mileage if that's what it took to get rid of the problem. smile.gif

[ 05-17-2002: Message edited by: Livin2DMax ]

[ 05-17-2002: Message edited by: Livin2DMax ]</p>