6.7 surging

[Pakrat]

Anybody have any ideas why my son's 6.7 would start surging suddenly? Really don't know what else to call it... idles at 500 to 800 and will not go over 1200 RPM. Thanks... any thoughts are appreciated..

 

[xcc_rider]

Can you give more info on the truck?
Deleted, when/how?, mods, stock, codes, miles, maintenance done, recently?
You know, anything that would help.

 

[Pakrat]

Truck is 2009--- completely stock...no codes... 140,000 miles ....all maintenance done within last 5000 miles. Started this erratic idling when he started it in the morning a few days ago. He thought possibly a fuel filter and changed that but no difference. He thinks it is the DPF or the cat.
Thanks for your help...

 

[xcc_rider]

I doubt its the exhaust. Turbo maybe but not the cat or dpf, yet...
He can check for exhaust restriction by cracking open the flange upstream of the nac and starting the engine. If it goes away then its nac/dpf related. Regretfully you can't check the cat as there's no flange to crack open.

Can he check or have it checked for pending codes. Could be a clue.
Any gauges like boost and rail press? If not then there's a free gauges phone app (torque app) you can use to monitor the pressures and help troubleshoot the issue. You'll have to buy the obd dongle on eBay for $20 but its well worth it.

Did he see anything in the fuel filter? Not sure how cold you get but fuel gelling could be a cause. He can cut in a 0-15 pressure gauge on the cp3 inlet line and see what the supply pressure is. Anything less than 5 would indicate a fuel supply problem. (Filter, intank pump, screen)

There's so many things it can be that without some gauges you're shooting blind.

 

[Pakrat]

Thanks XCC. I will pass the info on to him. He doesn't belong to TDR but maybe this will convince him to join.

 

[Pakrat]

Quick answer to you... Not fuel gelling up here. Outside is temp is running about 45-50. Nothing unusual in the fuel filter. As far as putting a code scanner on it, hasn't been able to since he can"t drive it. we will see.... Thanks...(-:

 

[Missouri Mule]

You can put a code reader on it with out it running.

 

[Pakrat]

OK..I didn't realize that. I thought the engine had to be running to get a reading. Now to find a code reader... Thanks,

 

[Pakrat]

Today he told me that the readout on the truck came up and said DPF 100% full. Guess that isn't cheap to fix.

 

[AH64ID]

Are there any EVIC messages about the DPF being full or in limp mode? There is generally plenty of warning.

A dealership can force a regen, but if he can get it to operating temp (harder at idle) it should start one at idle too.

 

[Pakrat]

Don't know what EVIC means but it started this all of a sudden one morning...no warning. I will send your note to him and he can try...Thanks,

 

[AH64ID]

Basically the smart overhead... it should have told him DPF 80% full, DPF 90% full, etc... It should also now tell him it's 100% full if that is truly what is going on.

 

[Pakrat]

It is telling him 100% full.

 

[AH64ID]

It is telling him 100% full.

I reread what you wrote and misread it earlier. I though you said the code reader said the DPF was full, not the truck.

He still should have gotten a 80, 90, limp mode soon, etc messages prior to the DPF Full. But that really is irrelevant at this point. He may be able to idle it and regen out of 100% or he may need to have it towed to a dealership to force a regen.

 

[Pakrat]

I don't think he got any warning..80%, 90%, etc. He is going to try idling when he gets off work. Fast idle and get it as warm as he can.

 

[AH64ID]

I would plug it in for a couple hours and then try. Fast idle with the exhaust brake if it lets him and once it is up to temp turn off the exhaust brake and go back to normal idle. That should allow the idle regen to take place, which should increase the rpms to 900.

 

[xcc_rider]

Have him crack open the flange like I posted and see if the surge goes away. If not then its another issue that's not coding yet and filling the dpf faster than it can regen.
One thing about dpf's, they're rarely the cause of a problem (except extremely high mileage - end of life dpf's) and a great indicator of another problem that's creating way too much soot like injector, fuel pressure, egr valve, turbo or sensor issues.

I haven't heard of the idle regen capability. Don't know if it will work but won't for sure if there's another problem.

 

[AH64ID]

I haven't heard of the idle regen capability. Don't know if it will work but won't for sure if there's another problem.

It was released mid MY08 and was a flash for 07-08 trucks and standard for 08.5+ trucks. It's how Dodge/Ram made the trucks farm/ranch/woods friendly.

It should work, but may not depending on the issue. It's worth a try.

 

[xcc_rider]

It was released mid MY08 and was a flash for 07-08 trucks and standard for 08.5+ trucks. It's how Dodge/Ram made the trucks farm/ranch/woods friendly.

It should work, but may not depending on the issue. It's worth a try.

Cool, learn something new everyday.