SES and P0106, P0402

[Mark Rinker]

I have noticed an occasional rough idle with 2006 K3500 SRW. No smoke, no fuel knock (maybe the slightest marble-in-can rattle just when you lift), good mileage and normal power.

Comes and goes, but when its present, its noticable enough to get your attention compared to the normal, smooth silent idle all the rest of the DMaxes have.

Ideas? I am running fuel treatment to see if this helps. So far, no change. Too soon for injectors, but they are under warranty just in case.

[Mark Rinker]

Started a new thread after SES illuminated and I pulled these codes. I am certain the intermittant rough idle reported under the first thread is correlated with the SES, and these codes:

P0106 - MAP / Baro CKT Range Performance
P0402 - EGR Flow Excessive

I cleared the codes, they stayed off for a few errands around town. This morning, I was hooking up a trailer, and actually heard the exhaust note change while idling, sort of like someone put their hand over the end. When I got back in the cab, the light was on, and the rough idle had returned...

Any ideas what the problem might be? How many miles on Emissions Systems Warranty? Damn I don't need any more repairs right now...

[Kennedy]

Stock intake/stock filter?

I'd start by checking for loose clamps on the intake system.

Also possibly related is the fact that some LBZ and LMM engines (moreso LMM from what I understand) have had issues with moisture/icing on the MAF sensor. We've also seen some odd occurrences of P0101 codes again mostly LMM.

The noise you hear in the exhaust is the turbo cycling. This keeps it free, plus can be part of the EGR testing ritual.

On a semi-related note, there is a programming update for the LBZ that adds EGR fast cleaning. I'd suggest applying the factory update for starters as teh LBZ EGR system can be pretty problematic.


This update will be in the revised tune I plan to send to you shortly. I can do the stock ECM N/C if you send or stop by.

[Mark Rinker]

Thanks for the info, JK. Stock everything.

I will check for loose fittings, as for MAF icing, it would seem unlikely as it has been moderate in temperature (~28F) during these occurances - and never had the problem during the coldest (-20F) days of winter. However, the humidity has been higher, and maybe I am actually melting snow or ice out of the filter that accumulated during the winter? Hmmmm...a new air filter is probably in order...

I have an EGR block-off plate, but not installed on this truck. Recommended, or no? Would it solve this problem, or compound it?

[Kennedy]

Back in the day (mostly before my time too) they used to talk about "turnpike icing" where the air entering the venturi would start to build frost/freeze. This can happen in many conditions and doesn't need to be excessively cold. It could also be simple condensation. Either way, GM added an extension tube to the sensor and from what I understand, this solves the issue.

The EGR blocker will stop the 402 and cause a 401 and 404 so it's a tradeoff.

[Mark Rinker]

Humidity has been high as we are melting lots of snow, and temps are below freezing point.

I am beginning to think this might simply be a seasonal problem, that can be corrected with the info you shared - the GM retrofit.

Light went out today on its own. I am going to run the truck and see what unfolds.

[GordonMarks]

"moderate in temperature (~28F)"
"MODERATE!!!"
You guys are wackey!! That's COLD AS HELL!!

[Mark Rinker]

"moderate in temperature (~28F)"
"MODERATE!!!"
You guys are wackey!! That's COLD AS HELL!!

Yeah, you are right. But all considered, 28F in February feels like a heat wave after 30+ days in the negative range during December and January.

You haven't lived until you walk out to your truck at -30F and the handle for the door snaps off in your hand!!! We're freekin' nuts for living up here, I agree. Was in Florida last week and each trip looks better and better...

[spongebob]

Mark Rinker, what happend??