Diesel Rough Idle?

Discussion in 'Hangar Talk' started by Matthew K, Oct 23, 2016.

  1. Matthew K

    Matthew K Line Up and Wait

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    Hello all!

    I own a 99' Ram 2500 with the 5.9l Cummins. As of yesterday, my truck has been behaving weird. When I started the truck for the first time yesterday, it ran like it was about to quite for about 10 seconds, then normal, then a slightly high idle(even though it was only 60 degrees out).

    This morning(42 degrees) the grid heaters came on, started truck, same issue. This only happens on the first start of the day, if the truck is warm at all it runs as usual.

    Sticking valve? Injector? Fuel flow issue?

    I've included a mp3 of the startup on soundcloud.
    https://soundcloud.com/matt-bob-316708333/truck-rough-idle
     
  2. cowman

    cowman En-Route PoA Supporter

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    If it goes away quickly like that I immediately wonder if something is wrong with the grid heater
     
  3. mondtster

    mondtster En-Route

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    It is doubtful that there is an injector or valve problem. I also doubt there is a grid heater problem, as you'll know when those aren't working, and in the temps described shouldn't even be needed anyway.

    What it sounds to me like is when there are governor or pump/calibration problems. Do you have a tuner of any sort on this truck?
     
  4. Matthew K

    Matthew K Line Up and Wait

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    No tuner or anything. I haven't had this truck for a long time so I want to baby it for the time being.
     
  5. mondtster

    mondtster En-Route

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    Is this the first you've owned it in cooler weather?

    One thing I think you're going to find is that the older diesels can have a bit of a personality, particularly as they rack up mileage. I personally would not be too worried about a little surging like that.

    I would however make sure you have a good lift pump on that truck. Without one your injection pump will be starved for fuel, which is also used as a pump lubricant.

    I didn't ever deal with the VP44 Dodges too much but my gut says there is a quirk with the injection pump, which may or may not fix anything, and get expensive. I don't know how much you can see with a scan tool on those trucks but it might be worth having a look at what you can see with one.
     
  6. Matthew K

    Matthew K Line Up and Wait

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    I had this truck last winter as well, didn't drive it a ton then but never noticed any abnormalities. I may be wrong but I believe this engine has a relatively new injection pump on it...I'm going to replace the fuel filter on the truck this week since I've been meaning to do it since my oil change.
     
  7. denverpilot

    denverpilot Taxi to Parking

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    VP44 failure is usually preceded by in-tank lift pump failure. I will not operate a Dodge of that vintage (including mine) without a fuel pressure gauge. I also have an aftermarket lift pump (AirDog) mounted under the truck on a cross rail.

    (There's a few different good quality brands. They're all nearly bomb proof and guarantee you'll never starve the VP44 of fuel. Some like mine also include a fuel/water separator and another level of filtering prior to reaching the stock filter/separator. Some companies suggest removing the stock filter/separator when adding a pump like mine. I do not. Because there's also a fuel warming device in the filter/separator for winter driving.)

    The VP44 is cooled by fuel and when the lift pump in the fuel tank fails, it cascades into killing the VP44. You must have 5 psi or higher feeding the VP44 under load or it's going to fail quickly.

    And even at that, the VP44 will eventually fail. They all do.

    Mine grenaded pulling the fifth wheel in Nebraska on a hot day headed for OSH a couple of years ago. $2000 for the VP44 and labor, and I was on my way again in two days.

    I had the standard mechanical failure. The stator seizes and the impeller snaps off inside the pump. The other failure mode is the computer that sits on top is susceptible to heat cycles and can fail.

    Anyway back to the problem at hand...

    That sound sounds like fuel flow to me. But there's some different possibilities as to why.

    I'd get a fuel pressure gauge on it quick and see what it's showing under load and at idle. If it's the lift pump you might save the VP44. With my aftermarket pump I won't settle for anything lower than 13 psi feeding the VP44 but that's overkill.

    That's ONE possibility. How does it run when it's warmed up? Surging go away under load or once warm?

    If it's not throwing codes, more likely, and if the injectors are original, is you have one that isn't pooping off at spec anymore and it's creating a misfire.

    Injectors can be removed and pressure tested pretty easy. Bit less spendy than replacing a VP44.

    But I don't think the surging you're hearing matches an injector problem unless the computer is having trouble compensating for it.

    Any extra smoke from the tailpipe?

    Unlikely it's related to the grid heater if you see and hear it cycling. (Even in a truck with a solid electrical system, that bad boy draws a LOT of amps and you can see and feel and hear it cycling at idle from a cold start. It'll cycle until a couple of different parameters are met and the engine is then considered "warmed up".) Grid cycling sounds and feels lot like an air compressor cycling in summer.

    Loads down the engine a few RPM, headlights and dash lights dim a little when they're on, load goes away (alternator) when they're off. Goes back and forth until the truck comes up to temperature which takes about two miles of slow driving or a mile of normal speed driving. It'll never warm up at idle unless you have an exhaust brake and activate it to get some load on the engine.

    Other stuff it can be: Bad TPS sensor or camshaft sensor (usually causes problems above idle but not always on the TPS sensor - sometimes they develop a dead spot near idle and their output is erratic telling the truck that your fiddling with the pedal when you're not). Again less likely but it happens.

    Another possibility is there's a Fuel Control Actuator (FCA) that's on the VP44 that's replaceable that can go bad and surge the truck by not responding correctly to the computer controls also.

    And finally: Check for a cracked fuel line. Sucking air in will cause surging also.

    Could be a lot of stuff but it sounds like fuel to me.

    @gkainz turned me on to one of the best Dodge Cummins people I've ever met here in Denver but I don't know if he could do the diagnosis over the phone. I bet he could give the absolutely most likely things though. Give MaxTorq Diesel in Golden, CO a call and send them some beer money if they're right. Rob and Dawn are great.

    I see some monkey gave them a bad review a month ago on FB after blowing up his engine.
    Wonder if they've noticed.

    Would love to hear their side of that story, considering they rebuilt mine and studded it also and it's been a freaking tank since then, and Rob was very careful about the boost level on mine since he knew I was set up for and needed to tow heavy, not race.
     
  8. Tom-D

    Tom-D Taxi to Parking PoA Supporter

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    change the fuel filter and add winter treatment.
     
  9. denverpilot

    denverpilot Taxi to Parking

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    PS. Eliminate the possibility of huge stupidity and go out and open the water drain on the filter container before you start it next time and make sure you just don't have a filter/container full of water. Simple stuff first... heh heh.

    It's the (usually) yellow handle on the side of the fuel filter container housing.

    Drain a bit out and make sure it's diesel and no water. It's a little messy under the truck, can try to catch it but don't park where you don't want a diesel puddle or toss a big pan under it.

    After draining that (or any time you mess with the fuel filter container) make sure to switch the ignition on and then just BUMP the starter without starting the truck to run the lift pump and refill/prime the fuel filter container. When changing a filter you may need to do this a couple of times before start to not have the VP44 trying to suck air until the lift pump catches up.
     
  10. Vern B

    Vern B Pre-takeoff checklist

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    I also lost an injector while pulling a fifth wheel with a Dodge cummings. There was no warning, it just quit. Fortunately it restarted and would idle, but had no power. I was on a hill at the campground (had just arrived) and was able to idle in reverse off the road. The local shop wanted 4000 bucks to fix it, I found one online and with their labor I think it was 1800. Truck ran great before and after. I vote for fuel flow for the op s problem. If the fuel filter does not fix it take it to a good diesel mechanic and have it checked out. If it runs ok after warming up it is probably not too serious. Mine is a 2000 2500, awesome truck I have had since new. Still pull the fifth wheel with it, what they want for new ones is obscene!
     
  11. mondtster

    mondtster En-Route

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    That's kind of where I was headed with it. To me the audio clip sounds like the computer is trying to control things but something is worn enough that it doesn't work right until it warms up and parts change size. Or it could be something goofy electronically that doesn't quite work right until it gets warm.

    Obviously I wouldn't advocate going crazy until some basic stuff is checked like lift pump functionality. If the injection pump was recently replaced, why was it replaced and did the shop actually address the reason the pump went bad? Also, how good was the pump they put on? It could be that it wasn't that good to start with and it now has problems.
     
  12. PaulS

    PaulS Final Approach

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    Hook it up to an OBD reader, chances are a code is set.
     
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  13. gkainz

    gkainz Final Approach

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    Like Nate noted above - Rob at MaxTorq Diesel is a Cummins guru (he's also a current C-130 Flight Engineer and prior engine mechanic just to keep it aviation related) ... you can also post on http://www.dieselram.com which Rob runs for help.

    I'm glad to see Tom and Nate (finally?) :) got around to "check the simple stuff first" with the fuel filter and Water In Fuel separator.

    The next most common failures is the steel fuel line under the body and at the firewall to engine. But, when mine went, it just sprayed fuel as the most obvious sign of a problem.

    Check the simple stuff first, and then add a fuel pressure gauge to check the next obvious. But yeah, post up on dieselram.com as well.
     
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  14. Tarheelpilot

    Tarheelpilot En-Route

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    The big thing on the vp44 is it uses the excess fuel from lift pump to cool the electronics on the pump. It does still lubricTe as most pumps but what goes first is the electronic controls. They require more surplus fuel than the actual pump does for lube. Also the water/air separation on that series dodge sucks balls. I run an air dog filter setup. Makes the high pressure pump much happier.
     
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  15. Sac Arrow

    Sac Arrow Touchdown! Greaser!

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    Also check for deteriorated rubber fuel lines. A problem developed with mine where it became hard to start and the filter would lose its prime. Fuel was leaking out of the supply line. It was replaced under warranty, which fixed the problem.
     
  16. denverpilot

    denverpilot Taxi to Parking

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    I assume you meant to say you lost an injector pump? (The VP44)

    Losing an injector would be about a $150 repair not a $4000.

    $4000 sounds like a new dodge one. They want to give you an economic incentive to buy one of their new $60,000 trucks so new prices have gone through the roof. I think I was quoted $6000 installed.

    Almost no one buys new VP44 anymore as you noticed. There are varying quality rebuilds, some using the old heat soaked computer module on rebuilt pump hardware and some with new. And varying quality on the rebuild.

    We ended up with one done by mid-continent Diesel as I recall. About middle of the road on quality level I'd say. But then again we were in Nebraska and didn't want to wait to have a custom rebuild flown in which would have added a couple more days to the parts time.

    Picky people will pre-buy the VP44 they want ($$$) and carry it around with them or have it somewhere someone can FedEx it to them when they break down eventually. Problem with that is the core is worth quite a bit and you need a place that'll take the core of the dead one a long time after you buy and send a check, or you're just out the core charge. Or know a custom shop that stocks the one they want.
     
  17. Zeldman

    Zeldman Touchdown! Greaser!

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    I am a little late here, but it sounds as if it may be trying to lose its prime. Try pumping the primer before starting and see if it changes anything. Check the rubber ring on the fuel filter.
     
  18. Vern B

    Vern B Pre-takeoff checklist

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    @denverpilot, yeah, I did mean the pump. Wish it had been an injector! That pump was about the biggest repair I have had on it tho. It did have a gear start slipping a few years ago and I had them beef up the transmission while they were in there, pulls a load much better. Leary about buying one of the new ones. They put so much on them that is not needed, just more to go wrong. I had a Poulin chainsaw the was perfect for 15 years, then I got too aggressive with it on a big tree and it burned up. Bought a new one and it is junk, sure not like they use to be. Same with any household appliance. I am afraid it would be the same with a new truck, even though they want more for them than I paid for my first three houses!!
     
  19. Matthew K

    Matthew K Line Up and Wait

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    I completely agree here! I mean for business's they can pay for them because the trucks make money for them. But in my opinion gone are the days where you could get a diesel and get off cheaper then the gas in the long run. Especially with DEF. To me it seems the majority of none business people buying diesels that don't tow all the time(excluding half tons) these days are those that are probably overextending themselves in terms of how much they spend on their vehicle IMO.
     
  20. mondtster

    mondtster En-Route

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    Those days have been gone since the '90s, when you could buy about two gallons of diesel for the cost of 1 gallon of gas, and the diesels got better mileage to boot.

    As far as who buys what goes, it's America. We can still buy what we want and daily driving a truck that a person probably doesn't really need is still more useful than buying an airplane or boat which sits for the majority of the year. :)

    But I know what you mean. My family has owned diesels exclusively for the last 15 or so years. I can count how many times I've had a trailer hitched to mine in the last year on one hand, but having the truck and the power to do it easily sure is nice. Mine is not new and I don't owe anything on it though.
     
  21. mondtster

    mondtster En-Route

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    Believe me, if the OEMs could get away without putting the extra emissions stuff on them they would. All the extra equipment is one of the major factors in the rising prices too. But I can't complain, the new emissions regulations and testing are why I have a job. :)

    Even your old VP44 trucks are the product of tightening emissions regulations. The controls necessary to meet the regulations were just more simple back then.
     
  22. Matthew K

    Matthew K Line Up and Wait

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    Yea I really wish that diesel still cost less then gasoline(especially considering it cost less to make), but supply and demand I guess...Don't get me wrong I love my diesel truck, and I love having the extra torque even though I don't tow much, I just more or less mean that many people who buy new diesels today not for the purpose of towing, seem to be buying 50k+ trucks when financially they should be buying a used diesel for under 30k...but I guess that's a problem that people have in all aspects of life, cars, trucks, planes, etc. :)
     
  23. denverpilot

    denverpilot Taxi to Parking

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    A new diesel pickup costs 1/2 of what my first owned home cost me. A comparable housing purchase today would be $250,000+. The inflation numbers are a well concocted lie and wages aren't keeping up. House of cards.

    There's nothing on a pickup truck that's worth $60-$70,000 and there's little in a cardboard and 2x4 tract house worth over $300,000 either.
     
  24. Matthew K

    Matthew K Line Up and Wait

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    UPDATE!!
    I usually don't let my truck go below a half tank for various reasons, this issue started occurring when I let the tank get to right above 1/4 of a tank. So, I filled up yesterday, and this morning(same parameters) I didn't have the issue. So now I'm wondering if maybe its a sign of the lift pump failing or issues with the pump pickup in the tank? But I'm not sure why it would only happen on the first start of the day.

    Let out a small amount out, didn't notice any water in it.
     
  25. denverpilot

    denverpilot Taxi to Parking

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    Could be lift pump, could be old fuel contaminated with something (how long did it sit when you said you didn't drive it much?), could be something gummed up that slowly cleaned up because you've been driving it more...

    I'd still want to get a fuel pressure gauge on it to see what pressure is doing at idle and under load. It's really the only way to know for sure, because before the VP44 fails, you might be sending 0-5 psi to it (not enough) and it'll still run.

    If it sits a lot, a quality anti-gel/cetane enhancing/anti-mold additive could be worth a few bucks at fill ups. I'm usually not a fan of that stuff because it's often a waste of money on a regularly driven diesel, but when dealing with diesel that may sit for a long time (data center generators) I know they always get treated and the exercise cycle is set up to use more fuel than absolutely necessary because it slowly rotates what's in the tank. Diesel tanks sitting with fuel in them love to grow stuff in some environments.

    I won't get into the religious war about which additive to use other than to say use something Cummins approves of.

    Did you peek at the filter? If it doesn't look new, and has discolored crud in it, get it out soon and then check and replace often until you get it to come out looking clean again. You may just have a tank full of crap and the pickup got partially clogged when the tank got low.

    Just thoughts.
     
  26. Matthew K

    Matthew K Line Up and Wait

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    Haven't looked at the filter yet...going to be replacing it later this week anyways. It doesn't sit anymore, I drive it 30ish miles a day Monday-Friday now. When it did sit it still was driven at least once a week since at the time it was an extra vehicle. I'd like to get a fuel pressure gauge on it also, but I'd rather not have to pay a mechanic to do it. Also, if I floor the truck from a rolling stop it takes what seems like forever to respond, but from a dead stop does great(so that might just be turbolag or gear advantage) would that be a sign of low pressure?
     
  27. Crane Pilot

    Crane Pilot Pre-takeoff checklist

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    It sounds like to me its sucking air or like Denverpilot has said a lift pump going bad. I would also drain the filter sump, then add a quart of trans fluid to the fuel tank on the next fill up, just to clean the fuel system. Ok i know yall are saying trans fluid in the fuel ????? , yes it does work. I used it all the time when i drove a truck OTR and when i had my Ford diesel , and its cheap. just my .02
     
  28. PaulS

    PaulS Final Approach

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    Hook it up to an OBD reader.
     
  29. Matthew K

    Matthew K Line Up and Wait

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    For those of you that mentioned a fuel pressure gauge, is there a cheap one you'd recommend?
     
  30. Craig

    Craig Line Up and Wait

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    Matthew: If the problem is consistently happening at a certain tank level, you probably need to look for a split standpipe in the tank. If the split is exposed to air, being parked for a long period of time will allow the head pressure in the pipe to bleed off thru the crack and you will be sucking/pushing a slug of air into the fuel system. Certain VW's are bad about the check valve at the bottom of the lift pump getting crudded up and doing the same thing. No clue if Dodge uses a check valve on the bottom of the pump, but it should be checked too.
     
  31. denverpilot

    denverpilot Taxi to Parking

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    Sorry no help there. Mine is a sensor on the third party computer.