Hey guys, so I got my 2005 GMC Sierra back in March this year. It ran great until a month after I got it. Started falling on its face at speeds between 45-55 mph, rpms run all the way to 3200 rpms so I don't think its limp mode. So I changed the fuel filter to a cat 2 micron, then I started getting MAF performance low codes. I cleaned the MAF, still popped so I installed a new one. Also new airfilter for the K&N intake. Didn't fix it, so a buddy lent me his efi live v2 to data log and found the egr motor to be barely functioning, only reaching 2.1v at WOT after it threw codes for low egr flow. Now the kicker is the truck has a brand new egr cooler and valve as I suspect it was deleted before since the Carfax says the truck failed smog in Cali and the next day had a cooler, egr, water pump, right bank injectors replaced and thermostats. So I replaced the motor as the valve was clean on the egr and the issue went away for almost 1 month. Now I checked the fuel lines for kinks, none. Data logged FRP and command vs actual were dead on. Data logged my vanes, desired and actual are spot on, goes to 0% on command with the efi live controller. I cleaned my vgt pos sensor, nothing changed. I then checked my wireharness and no signs of chaffed wires, no boost leaks or holes on the charge side of the turbo so I installed a egr blocker plate. Then the truck ran great, boost was hitting 23psi with ease, before it wouldn't go over 16psi. Then 2 days after the plate install on the 3rd ignition cycle it falls on its face again, 16 psi max boost at 100% throttle pos, but the weird thing is the problem is intermittent. It does it of the truck is up to temp or cold, 10 miles down the road or 300 miles it doesn't matter, no rhyme or reason. When it falls on its face at between 45-55mph, diesel clatter gets louder, turbo gets quieter, doesn't blow black smoke or any smoke. When its making low power my fuel rail pressures stay at 25,-26k psi, vanes stay spot on, MAF flow is in limits and doesn't fluctuate. Engine will idle smooth and run smooth, but just looses power. Sometimes when I clear the codes it runs fine for about 15 miles then falls on its face again. As far as I know about the tune, its stock seeing that it doesn't create much boost even when it runs good. Now efi live has been suggested by my buddy, he thinks that my fuel tables are getting wacky from the egr so he says get the egr tuned out and a tune made for all my airmods. Any help is greatly appreciated, I know its a long post but I have been reading post after post for months on this with no avail!
Odd LLY problem
- Thread starter TimmyLLY
- Start date
His post says actually vs. desired is spot on. From what I've seen sticky vanes haven't caused a pickup to fall on it's face. Not saying it won't and I'm sure others will commit if they've come across it.
What codes did it set? If not I would see which ones it's setting.
I would get a know unmodified stock tune, turn off the EGR in the tuning, and then flash it into the pickup.
How many miles are on the pickup?
When if falls on it's face does it have alot of black smoke?
I hope this is some what helpful.
Yellowchevy
Miles are 160k, I get P0101 maf, P0299 turbo underboost and sometimes P0401 but the egr assembly is all new including the cooler. I dropped a block off plate in, it did feel like it helped but still getting codes. Would these codes cause the FICM to pull fuel or timing because of "lack" of air?
My lly had an issue with the vanes sticking at a certain point and did this. Not saying it's your problem just to watch vane position a little closer. Mine also had the mass code and under boost code plus a p0263 or something.
The command and actual positions show they are spot on, but I also don't know what the expected range for the vanes. I'll do another log for vanes today on my way to work and I'll post the results. If my vanes were sticking wouldn't I see black smoke too? It blows clean even when reduced power.
I belive its oiled. When I got the truck the old filter was trashed so I removed the intake tube and cleaned it really good. I tried cleaning the maf and still popped codes. So I got a new filter and maf, I read about the k&n filters being oily so I hit it with a little compressed air when I put it on. I do want to change it out to a dry s&b kit.
Yes i need to compare the logs to see what the differences are but when it's in low power my maf flow drops to about 350g/s but when it's running good I see as high as 450ishg/s. Does you guys think a faulty glow plug module could be sending signals throughout spamming everything? My friend pointed out that I had all these issues the day it threw this code in his driveway. Since then I have an abs code for both left and right front wheels(new hubs and sensors there too) and multiple bcm codes for lost communications with various circuits like my ignition ect. I can pull them when I get home from work and post those too. The maf is a new sensor and I cleaned it again today to be sure it's clean.
Update: So today I pulled the map sensor and it was completely trashed. I tracked down one at a dealership near by and took the ride to get it. Got the new map sensor in, cleared the codes and went for a drive. Got 2 miles and maf performance low pops up and I make no boost. Truck struggled hard to make 13 psi. I'm feeling kinda defeated. I replaced the air filter, fuel filter, maf sensor, map sensor, egr assembly and blocked the egr for good measure. Are these codes causing my truck to make low boost or is it the low boost that's throwing these codes? Do I need an efi live tune to rescale the maf for the intake?
If you have a stock intake, I would stick that on to eliminate that variable. In theory, you shouldn't need to re-scale the MAF for the K&N intake, but it clearly doesn't like something about this setup.
Since you mentioned a bunch of other modules are throwing codes, you might check the grounds and make sure they are clean/tight.
Since you mentioned a bunch of other modules are throwing codes, you might check the grounds and make sure they are clean/tight.
Alright guys an update for anyone in the future with this problem. The culprit this whole time for me was the intake and exhaust mods without a tune. I took a step back on all the problems and realized that the intake was larger in diameter, so airflow is going to be slower, tricking the maf and throwing codes. Now many of my friends were skeptical but I went ahead and got an efi live tune written for me and I explained the problems to the tuner. They emailed me my tune, I loaded it and since then I have had zero issues. No more maf p0101 codes and no more p0299 from my turbo just spinning up 16 psi. Thanks for everyone's input, it steered me to the resolution.