Engine/Transmission (1998.5 - 2002) Engine missing at idle

[chughes]

I have recently noticed the engine missing at idle rpms, with no issues at any other rpms or power settings. It is on my 2500 and I now have about 122k on it and have had very few issues with the truck. Fuel filter has no more than 5k miles on it. Does this sound like a lift pump issue?? I would appreciate any input.



Also anybody know why some engines belts chirp when shut down and some don't. My 2500 does most anytime that it is hot or hot outside, but the 3500 have never heard do it, no big deal just curious, I was concerned that maybe the 3500 has less compression or something...



Thanks

Charles

 

[Pit Bull]

My 2000 3500 4x4 auto alway chirp. My 2002 6 speed never chirp. I have heard that the autos chirp and the manuals don't, but you have 2 manuals so what can I say

 

[Puffin Smoke]

I am willing to bet its the compression from the engine and it suddenly stopping when you shut it off is why it chirps. Thats when mine does it. I have heard that compression is like 17:1 or some thing like that. Not sure.

 

[LSMITH]

The chirp is the accessories continuing to turn when the engine stops, a little inertia is all.



The idle miss could be a lot of things. First suspect is the valves out of adjustment, second is an injector not working correctly. The best way to find out what is going on is to take it to Cummins, for $150 or so they can run a really thorough battery of tests on it and likely will find a problem if it is of any significance. The lift pump should not have any effect on idle quality. Before you do anything drastic get out there and adjust the valves.



If you want to shadetree on it a little you can loosen one injector line at a time and see if the idle changes at all, then at least you will know what hole is not working right. BE CAREFUL!!!! INJECTION PRESSURE EVEN AT IDLE IS ENOUGH TO PUNCTURE YOUR SKIN, YOU CAN BE INJECTED WITH DIESEL FUEL AND POSSIBLY EVEN DIE!!!!! Not kidding either, be careful. Wear thick leather gloves, long sleeves prefferably of leather also, and do not get close to the line at all for any reason. Use the longest wrench you have. If you find a hole that does nothing to the idle situation when the line is loosened you can pull the injector and have it tested, and/or do a compression test on that cylinder. If both check OK you can have the pump tested. I would be willing to bet that it is either A) an injector problem, B) valves out of adjustment, or C) and injection pump problem.

 

[chughes]

Thanks for the replys so far -



Just to clarify the missing is very inconsistent, it doesn't miss on every revolution, I would say somewhere around every 50 to 100 revolutions (3 to 5 seconds apart, then it may stop for 20 sec and start again) and also it seems changes depending on engine temp.



Also I was not worried so much that my 2500 chirps, because it makes sense that it would. My concern was that my 3500 doesn't - both identical trucks other than weight rating

 

[cmills]

Charles, My truck used to miss at idle real bad. Took it to scheid diesel and found out it was a bad crank sensor or cam sensor. (sorry, can't remember which one it was).



Cory

 

[Ncostello]

chughes

I'm starting a support group this week for this exact problem. I am going to be the president of the club.



Actually, I do have this same exact problem under the same conditions. Mine gets worse and more consistent as the engine temperature get higher. Cold, you'd never know it. And the other day, it ran perfectly fine even when warm... until I made a mental note on how the engine sounded smooth and much quieter at idle. It was a jinx. It started acting up about 5 minutes later. . ,



Just a run down, I installed new filters, new lift pump (it was bad anyway), di-electric coated all connections (some twice), replaced crank sensor, cleaned the IAT sensor, inspected the MAP sensor, Cummins Service Center diagnosed two bad "injectors" so I installed 6 new ones, ran three tanks of high quality diesel with biocide and Stanadyne, and changed the filter again. I also installed a BHAF and straight pipe exhaust for good measure just in case... .



None of this helped me. Still does it same as ever. My prognosis is its the VP44, a fuel connection sucking air, or bad fuel cross over tubes that may be pullin in some air or dropping pressure somehow... or something like that. Has to be.



I've always wondered about the valves being out of adjustment... considering it does this when its fully warmed up. But didn't consider it cause the adjustment interval is at 150K and I'm at 80K. Who knows. I've got a good theory right now concerning the VP and am working on ruling it out. I really dont think its the cause. But I dont want to bore you with that one.



And dont mention warranty in my case... just never mind about that.

 

[chughes]

ncostello,



Thanks for the info, I will be the first member of your club. I'll leave my alone and let you do the trouble shooting since you are the president hehe. It sounds like there are numerous possible causes, I will probably check vavle adjustment since I'm at 122k.



Warranty - I thought that they would fix anything - you know a NO HASSLE garuntee - oops we were not going to go there - sorry...



Anyway keep me in mind if you find the source of the problem and I will do the same.



Thanks

 

[Vaughn MacKenzie]

Heck, I've been a member of the club for 2. 5 years and 78,000 miles



Mine has idled poorly since new. I guess I've just gotten used to it. I've done all sorts of things like new injector tubes, re-pasted the electrial connections, adjusted the valves, no effect at all. Put an scan tool on and ran the injector test and found all cylinders nice and even. Unevennes is random.



Since I have great power and mileage, I hesitant to invest the money & effort to resolve it.



BELT CHIRPING: Autos do it more readily because they have lighter flywheels and therefore the engine stops much quicker when you shut it down.



But on a 5-speed?

Time for a new belt buddy



Vaughn

 

[Ncostello]

I dont know what it is, but I will not give up. Its like a little game for me now. Seems so elementary... yet so difficult... mainly cause the VP is impossible to get bench tested. Nobody can do it. So its either buy a new one or diagnose (guess) all the other things it could be. So I'll do everything else first.



However, work has a temp gun I can point and tell the temps of the individual cyls. They use it on heavy equipment engines and such. Mechanic told me to check each cyl temperature and look for oddball temps (low) on suspect exhaust ports. Maybe I'll get lucky. Cost=0 too.



And my friends who said the miss was all in my head cause they didn't hear it... well they aren't saying that anymore since I installed the straight exhaust. It is quite pronounced now.

 

[Ncostello]

OK, I'll give my theory on why I think its not the VP. At least why I want to believe its not a $1200 part.



The firing order is 153624. The VP radial distributor has three sides from what I understand. Each side is responsible for pressurizing fuel to each third cyl. ie: 1-6, 5-2, 3-4 groups get their fuel charge from the same "area" of the distributor. So if one side of the distributor is not making proper pressure, you'll have bad delivery to one of the three groups of cylinders. I once stated here that the Cummins mechanic told me 2-5 were missing which played right into this belief (St. Laurent informed me of this possibility). But after sifting through some paperwork, I noticed the shop print out paperwork said "MISS on 2 and 6 cyls" Therefore, if the distributor operation theory applies to the firing order, I should have 4 cyls missing as the 2 and 6 are not a group to the VP distributor gear. The distributor cant deliver good charges to 2 and 6, but not 1 and 5. These cyls all look the same to the VP. Thats why I rule out the VP... for now.



I'm not trying to take away from your question chughes, but I'm just trying to rethink all of my troubles out loud to help. Having a full electronic diagnosis sure could help you see which cyls are troubling you. INSIGHT is the program to have them use. Cummins has this.

 

[LSMITH]

I adjusted my valves on my 99 at 70K miles the first time, and only 4 were in spec!!! 2 were at the limit and 6 were over, and a couple by a lot!!



The 150K mile interval is bunk, I adjusted again at 105K, and they were off about . 003" on the intakes and . 008 on the exhuast. Very few guys that have checked them at 100K have not needed adjustment. Mine are on a 25-30K cycle from here on out. It does make a difference in sound and power. Mine idles pretty good, but I have seen the valves cause a poor idle and even a total lack of idle in others. Takes about an hour and it is free. Adjust your valves.

 

[chughes]

LSmith



Thanks for the reply, do you know where I can find the seq of ops for adjusting the valves and the proper clerances, without buying a service manual, not that I shouldn't own one.



again thanks for the info.

 

[Vaughn MacKenzie]

Strange. I'll have to check my valve lash again. Did it around 30K and it was extremely close, maybe . 001" was the most it was off. Was planning to wait 'til 100,000.



Vaughn

 

[LSMITH]

Take a look at this thread, look at the posts by Chad Sheets. https://www.turbodieselregister.com...?s=&threadid=22606&highlight=valve+adjustment



He used to post here regularly, and typed it up better than I could. Don't know what happened to him, but he was a great source of info. Values for valve lash in inches are . 010" on intake and . 020" on exhuast. I have been using his procedure since he put it up, straight to the point and easy.

 

[chughes]

Thanks for all the info, I check my valves and after 122k found the following:



Intakes all ran between . 30-. 38mm



Exhaust between . 50 - . 55mm



These fall right where Chad had suggested, but interestingly enough the problem went away, but two other things happened all about the same time our normal highs dropped to about 35-40 instead of 60's and I fueled up, although before I went through two tanks, but who knows. I will wait and see.

 

[Ncostello]

Whats this you say... "the problem went away" by only checking and not adjusting your valve lash? Sort of disappeared?? I'm sorry but I'm going to have to revoke your membership to the Bad Idle Club. Only members with constant bad idles that drives owners crazy no matter what they do are allowed. Guess that means its just me and Vaughn. Membership just dropped 33%.



Seriously though, outdoor temps make no difference on mine. Neither does where I purchase my fuel or any additive I use including biocide. One note however, I did happen to speak with a guy at the fuel stop who was from out of town. He had a 98. 5 so I started conversation with him about any problems he had. He said his lift pump went out at 90K and starved the VP for lube and cooling fuel. His idle also missed while in neutral (auto truck) but not in drive... which is what mine does under no load idleing (mines a 5spd). He had the VP and lift replaced and its fine now. Kinda what I've been suspecting on mine since my lift pump was out when I bought it used. But I still gotta check my valves since its free.

 

[MWilleford]

Club VP needed??

Count me in.

It came back. The un-rythmatic miss at idle.

(occuring after the engine is warm. no other performance issues, just That Extremely ANNOYING MISS)



Facts I know to be true on my problem.

Bought truck used(60k) never had problem for 25k.

@ 85k, i filled at a truck stop (not the usual) and noticed later that day a slight miss. I would have noticed this earlier IF it had occured because i can feel the miss every so slightly through the shifter. . I knew it was a new problem.



I immediatly went and checked Lift pump-- all good, and changed the fuel filter.



This slight idle miss continued for 6k until one day i used Powerservices Diesel Biocide. It went away as quick as it came.



I though, OK, all good. Since the miss went away, i had to replace the pift lump and installed a Comp. The thought the miss was associated with fuel alge or fungi. . whatever-- I had fixed it.



All was good until 3 weeks ago, I figured I would "Clean" the fuel system by adding another shot of the Biocide (same container as the first time). Well, a week after I did that... THE MISS CAME BACK (102k)! I was running the same tank of fuel I added the biocide to.



However, I have recently installed (1. 5 month ago) an aux fuel tank that feeds the main tank. The tank was not new, and most likley had old fuel in it. BUT i had run 2-3 tanks through it before it showed up. (I would have assumed the problem would have occured a lot sooner)



I am going to saturate the fuel tanks with the Boicode (2X shock treatment) and report my findings.



Valve adjusment: hot/cold engine --miss only occurs when hot?

Fuel: winter/summer fuel --?

Neil, sorry to hear about your warranty.

 

[Puffin Smoke]

Idle fluttering?

My idle is fluttering. What could it be. Just changed the lift pump last night so I havent noticed it yet if it stopped. Im thinking maybe its the #1 fuel because I had this problem last year of it stalling when going in gears. Last weekend I just adjusted the bands and reverse is a ***** when going in. Stalls alot. Im thinking that #1 fuel is the cause because ive lost mileage also. Diese fuel addative doesnt seem to be helping since ive added a quite of bit to my last fill up. Any of you alaska guys know if they are still selling #2 fuel in Anchorage anywhere. I know we had this converstation last year. And only somebdoy in Fairbanks did. Could it be a sensor causing my fluttering idle?

 

[WestTN]

belt chirp

A Goodyear Gatorback belt does not chirp. Just about everything else does.