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Discussion Starter · #1 ·
Hey Folks,
I've got an 05 LLY that is stock without a tuner, a 6" lift/35's (133,000 mls), and I am the only owner. I am getting the codes in the title along with low power and loads of black smoke; no CEL. It isn't really obvious unless towing my horse trailer and it seems to drive fine without the trailer, but it's just not as obvious. It does it all the time when towing now and had done it intermittently before. Oddly enough it would do it at the same spot, every time (four times), about 45 minutes from home, but would reset itself after stopping.

I've checked all my turbo boots, pipes to the intercooler, cleaned the MAF, cleaned the turbo vane sensor, changed the air filter, and fuel filter too. According to a mechanic my injectors are reading like new (they have been ice-picked and the harness at the alternator bracket wrapped in rubber years ago). Unrelated, but today I have changed the oil and filter, as well as the trans' fluid and filters, put on a new idler arm, and a window regulator...

Anybody have any ideas as to what my problem is? The intercooler pipes had a fine layer of oil in them (EGR is hooked up). I cant find the MAP sensor or boost sensor, so could use some help there too.

I know the codes are for the MAF and under-boost... just not sure what else I should check or if my turbo has kicked the bucket. I can barely hear it spooling and the computer only showed it at 14-15 psi (sea level).

Thanks.
 

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it is possible to have sticking vanes and or the maf is bad or needs to be cleaned? Possible it could be a fuel issue. really hard to say
 

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Discussion Starter · #3 ·
Thanks for the response. I can use the diagnostic computer anytime, but I need to know what to look for. The problem is that my buddy with the computer is not a diesel mechanic and neither am I.

How would I know if the MAF, Boost sensor, vane sensor, or fuel rail pressure return valve/pump are bad? I guess I need some spec's...
 

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Discussion Starter · #4 ·
I forgot to mention that those codes were read and cleared before I did all of the above work. After doing the work I hooked up the trailer and the truck was still blowing smoke and underpowered, but I just checked the codes again after towing and turbo under-boost code has not come back and the MAF sensor code has. Readings from the computer for the MAF looked like this:

27 g/s at idle
103 g/s at 2,000 rpm

1v at idle
2.05v at 2,000 rpm

Anyone know if those are bad numbers and the problem is in fact the MAF? I am going to go check wire harness for grounds around the IC tube when the truck cools off.
 

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Discussion Starter · #5 ·
Finally found the MAP tucked under the bracket where the two big electrical disconnects are on the front drivers side head. It was clean, but I hit it with some MAF cleaner anyway. I thought it was odd that it just hangs there not plugged into anything, but I guess it just measures ambient pressure.

Gave the radiator hose a couple of squeezes last night and now the truck is running at 210. At least that is what the gauge says. It had been right at ~180 before. I'm not sure it can be trusted because the speedometer and fuel gauges have gone crazy and I think I need to replace all of the motors in the panel.

I'm starting to wonder if the CAT is plugged up....
 

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Finally found the MAP tucked under the bracket where the two big electrical disconnects are on the front drivers side head. It was clean, but I hit it with some MAF cleaner anyway. I thought it was odd that it just hangs there not plugged into anything, but I guess it just measures ambient pressure.

Gave the radiator hose a couple of squeezes last night and now the truck is running at 210. At least that is what the gauge says. It had been right at ~180 before. I'm not sure it can be trusted because the speedometer and fuel gauges have gone crazy and I think I need to replace all of the motors in the panel.

I'm starting to wonder if the CAT is plugged up....
what about the MAF, have you cleaned that?

There was a issue similar to yours, the culprit was the CAT clogged, and the other similar issue recently was the sticking vanes issue
 

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Discussion Starter · #7 ·
I cleaned the MAF right after clearing the first two codes - P0101 & P0299. The under-boost code did not come back, but the MAF code did. The truck is not running well. At times the exhaust seems like it is oozing out (when it blows black smoke and has no power), so I think the turbo isn't working or the CAT is plugged up. I don't know...

Not sure what to do next. I've read a lot of threads where people change the MAF and the MAF is not the problem. I'd hate to spend the money if it isn't the problem.

What do you think I should do?
 

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Discussion Starter · #8 ·
Hooked the truck up to the computer again to test the vanes and noticed that the P0101 code was back again. The vanes are moving with the demand just fine as far as I could tell watching them side by side on the screen. I seen them go from 88% at idle to about 35% playing with the peddle. So, I decided to pull the turbo inlet off and check the turbine/impeller (?) and it was spinning freely with no play up-down/in-out. It wouldn't spin freely by itself for more than 3 seconds though, but it had been 20 minutes since I shut off the truck... I don't now if that is good, bad or average. The PCV had made a little mess on the outside of the inlet too.

I went ahead and changed out the MAF and the truck seems to be running better. Drove it around for a while and got on it every now and then. After about 20 miles and the sixth WOT evolution it seemed to really be picking up boost like normal with no abnormal smoke. I could hear it much better too. Think I'll hook it up to the trailer tomorrow and see how it does.
 

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Discussion Starter · #9 ·
Well...the truck was underpowered and smoking again today for a few minutes, but this time without a trailer. I guess it's not the MAF.

Maybe I need to take a look at the CAT. Anybody have any ideas? Could the EGR do this intermittently?
 

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take that CAT off first!
 

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Discussion Starter · #11 ·
Truck is running like crap - intermittently losing power and smoking like an old freight train when it decides to do it. Took it by a local diesel shop and they pulled the following codes of the day:

P0401** Exhaust Gas Recirculation Flow Insufficient Detected
P0404** Exhaust Gas Recirculation Circuit Range/Performance

Now that I am home I am going to take a look-see at that now. The way the truck is acting and everything I have read on this site is leading me to think that if I have an EGR problem then I might have a CAT problem too.

Something isn't right at all and I am starting to see tranny temperature when driving; I usually don't see that unless I am towing...
 

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Discussion Starter · #12 ·
I am pretty sure that the EGR valve was stuck. Took it all apart and cleaned the heck out of it until it spun and moved in/out easily with my fingers. Truck runs much better now and the codes are gone. I drove it back to the shop and it didn't throw any more.

There wasn't much carbon/soot around the valve or in the tube. The valve was practically clean and the tube had maybe 1/8" of stuff in it. Cleaned out the tube anyway...

Here's a lesson learned: DO NOT push on the spring cap around the EGR valve/rod. I did and two little keepers fell out and down into the heat shield of the exhaust manifold. Not only was it a pain to find the dang things, but putting them back onto the EGR valve/rod under spring tension was a literal pain in the a$$. I ended up putting a little dielectric grease on the rod/valve to stick the retainers onto it while holding the cap in with a screwdriver and then released the spring cap back onto them... It only took around 50 failed attempts to get it right.

I'll be keeping my fingers crossed that that was the problem and that it holds on until I save enough cash to buy an EGR delete, new exhaust, and tuner.
 
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