cummins isx with dpf blowing blue smoke

I thought these things were not supposed to put out any smoke, anybody know what's causing this, I've even seen Volvo and Macks with DPFS pass me and they're emitting what looks like yellow smoke! We have the Cummins ISX 450 and every now and then going down the road, they woof out one heck of a cloud of blue smoke. Dealer scratches head, as usual.

 

I too have seen these clean air machine belch large clouds of half burnt fuel into the air, must be clean smoke right???

 

I've got two 389's, one a family 3 (600) and the newest being a family 2 (500v). I have the same problem with the 500v 'puffing' a blue-white smoke cloud at shift changes, but only if the engine is in the process of an active regeneration process with the DPF, and only at cooler outside temps. The issue is known by the truck mfgs and Cummins, but they are playing dumb to end users and consumers. It seems to be isolated more so to the family 1 & 2 engines (385 to 500hp), and is caused by an off temperature DPF. I don't think the problem is as near widespread with the family 3 engines since they naturally burn hotter and don't go through regens quite as often. After some ranting on my part with the factory, I got some answers (alibet not what I wanted to hear) and was told the condition would not hurt the engine or DPF. Cummins has an ongoing project trying to isolate the exact cause, but still no resolution at this point. When I made my fuss, they thought the problem was isolated to the northern regions...not so. I don't think they believed me at first, but I have the video to prove it.

Anyway, it's quite embarrassing to be driving a new, shiny 389 with a 'clean idle' sticker pouring white smoke out the stacks. That, and the phantom engine miss that never manifests itself at the dealer.

 

Its pretty easy to crack a DPF if you have the regen inhibit switch on for too long and the lights start telling you to do a regen but the truck was taken all the way to the engine wanting to shut down. Now on the other hand blue smoke is still oil... so the standard diagnostics for blue smoke apply. Too much oil in the DPF would probably lead to overheating it and cracking it too.

 

Had a friend that got into warranty issues with Cummins over a DPF. They said he had the inhibit switch 'on' which caused the DPF to plug up. He maintains he only had it on while in the field for a short while and turned it off before starting his trip.

The drama made me reevaluate my options regarding ECM parameters. I disabled the inhibit switch function since it really serves no purpose in my opinion other than to offer the oem to put blame on the consumer for a DPF malfunction. The default settings prevent an active or passive regen at anything under 5mph. I still have the option of a manual/stationary regen, but have never used it, nor in the one-and-a-half years driving them have I ever been prompted to do so. Everything's been automatic so far.

 

It's funny, they all led us to believe they knew all about this technology, since they had been using it in the UK, and now you get the deer caught in the headlights look when something goes wrong. I also know people that have dpf Macks, and they are looking for lemon law lawyers, or just wanting rid of the trucks period. PA DOT bought a bunch of these Macks, and the dealer's parking lot looks like a PennDot garage LOL! Unbelievable. Found that taking our trucks to Cummins works better than the Pete Dealer tho.

 

Yeah, I hate to admit it cause I love the specs, ride, and power of both my new ones, but the total truck quality is lacking. It's been in the shop over 60 days within the first 5 months. If they don't have the problems fixed after the last attempt, I too will be sending all interested parties certified letters to start the Texas Lemon Law process. I won't go into details, but the problems I'm having (besides the smoking, which at this time I don't feel to be a pressing issue, and the engine miss) are not powertrain related. Let's just say I should have received a ShamWow and rubber boots with my truck purchase.

 

mine seems to do it every once and a while, here's my 2 cents, I think that it is bits of 'crud' from inside the filter breaking off, and burning up right away, I noticed mine do it a few times and in an after thought it seems to do it after hitting a bump, while the engine is pulling. p.s 2008 KW 475 Cat

 

Well, blue smoke is usually oil burning. See if your turbo is passing oil. As for the smoke in between shifts, we are hearing that Cummins and Cat are finding the turbo(s) are putting out more boost then they used too and respond better than they use to in change of load. Sometimes the boost drops off quicker than the fuel cutting back during a shift so there is slight timing gap where the engine is still fueling and the turbo boost is already gone. This ends up causing more fuel to be injected for the available air resulting in puffs of black smoke. Cummins has monthly ECM updates. It doesn't take long before your truck is out of date and needs a software update. To help with issues like this. Most are warranty. See if the calibration version is out of date.

 

I agree with heavyd on this, if you really feel like there is a problem then get it checked out, it is possible for your engine ecm to set active fault codes for the afterreatment system that do not turn on the engine light.