6.7L Fuel Knock, White Smoke

[hepperj27]

Need some help with an 08 Cummins 6.7l. The truck was tuned 6 months ago and had been running with no problems until about a week ago. The owner said the truck started smoking black any time he was on the throttle and occasionally he would get a fuel knock along with white smoke. Initially though he had a failed injector so he took it to a local shop and they checked balance rates and they indicated no. 2 and no. 5 out of spec. He had all of the injectors replaced. When he picked the truck up it started and ran normally until warmed up and then started having the same issues as before. Then thought maybe the tune was the culprit. Flashed in a known good file and had the same results black/white smoke along with fuel knock. No codes. Logs show every thing is running in normal ranges. Timing, Pulse, TP%, etc. all normal. No post duration as the tables are zeroed. Im at a loss here any help would be greatly appreciated. Thanks in advance.

[cumminsDK]

Need some help with an 08 Cummins 6.7l. The truck was tuned 6 months ago and had been running with no problems until about a week ago. The owner said the truck started smoking black any time he was on the throttle and occasionally he would get a fuel knock along with white smoke. Initially though he had a failed injector so he took it to a local shop and they checked balance rates and they indicated no. 2 and no. 5 out of spec. He had all of the injectors replaced. When he picked the truck up it started and ran normally until warmed up and then started having the same issues as before. Then thought maybe the tune was the culprit. Flashed in a known good file and had the same results black/white smoke along with fuel knock. No codes. Logs show every thing is running in normal ranges. Timing, Pulse, TP%, etc. all normal. No post duration as the tables are zeroed. Im at a loss here any help would be greatly appreciated. Thanks in advance.

Check compression and do a cylinder leak down test!

[hepperj27]

Check compression and do a cylinder leak down test!

Thanks for the quick reply. I don't think were having a compression issue though. Although I wouldn't know for sure until running the tests, the pickup starts very well cold with no smoke. The issues only arrise when the pickup is up to operating temperature and are not consistent as I can get it to run without smoke some of the time. Thanks again.

[anarchydiesel]

Turbo is likely the culprit, nozzle sticking open will give the symptoms you are reporting. Does the exhaust brake work when it does this?

[hepperj27]

Turbo is likely the culprit, nozzle sticking open will give the symptoms you are reporting. Does the exhaust brake work when it does this?

Yes the exhaust brake seems to be working correctly. Could an EGR valve stuck open possibly cause this?

Thanks

[cumminsDK]

Yes the exhaust brake seems to be working correctly. Could an EGR valve stuck open possibly cause this?

Thanks

You are correct with the fact it's running good cold means no compression issues must have missed that! I assumed EGR was deleted, most likely the culprit!

[hepperj27]

You are correct with the fact it's running good cold means no compression issues must have missed that! I assumed EGR was deleted, most likely the culprit!

Sorry I should have mentioned that first. He wanted to save some money so he decided not to remove the egr right away. But I've got a kit coming now should be here by this weekend. I'll get it put on and report back with results. I guess it was a case of should have done it right the first time.

Thanks a lot guys.