P0171 & P0174 codes - 4.4 LR3

[Howski]

Getting a P0171 and P0174 lean codes after a Seafoam intake treatment, repairing a crack in the intake resonator, and cleaning the MAF. Had no codes prior. I reset the adaptive values after this but the codes came back. Truck otherwise is running smooth (and peppier than before the above items were addressed). Double checked the intake hoses and vacuum hoses for leaks and found nothing. Understand fuel trims should be looked at. Fuel trims while cruising at constant throttle and light load are approx 7% long term and 2% short term. Off throttle coasting long term will increase to 13-14%. Anything else obvious I should be looking at before I throw a new MAF at it?

 

[discostew]

I would smoke test it for leaks. Also make sure the adaptions really got reset. SDD sometimes doesn’t do it even though it says it did. I’ve gotten in the habit of displaying them again to make sure all the boxes are really reset.

 

[Howski]

Have positively reset values a few times now and no dice. Any other method I can try to reset values (disconnecting battery?) just to be sure? Just perplexed how I got no codes when there was a visible crack in the airbox and now I’ve got one. Otherwise will look to smoke test next

 

[gmtech]

i am having same concerns. is there another way to reset adapts if do not have gap tool ? heard places that if you keep clearing the code and driving and concern is actually fixed fuel trims will come into spec after could drive cycles. is that true? it is with GM cars

 

[jymmiejamz]

If you fix the root cause of the problem and drive it long enough it will eventually adapt back to the correct values.

 

[discostew]

Like Jymmiejams said it will come back eventually once you find your problem. That said, a cracked air cleaner box will not bring in unmetered air. Dirty air maybe, but it’s all accounted for since it’s going thru that mass air sensor

 

[discostew]

If it’s lean smoke it for vacuum leaks, clean your throttle and start running 44K in every other tank of fuel. It takes time but that will clean out your injectors.
The way it was explained to me by an old Jag tech is this…They went from 4 or 6 holes in the tip of the injector to 8. The holes are smaller and get restricted. Flushing the shit out of the injectors is the fix.

 

[Howski]

Just to circle back since there have been some recent responses, I am an idiot. Pulled everything apart and there was a large crack on the underside of the intake pipe near the baffle, post-MAF. Swapped in one from an RRS (sans baffle) , reset adaptive values and been golden since

 

[gmtech]

i have been chasing this for the 2 months ive owned this. smoked system found cracks in intake duct. replaced with landrover part from british parts of utah. cleared code. made it 3 drive cycles and 50 miles. codes came back. removed and cleaned MAF. cleared codes. codes came back in 4 miles. replaced MAF and air filter cleared codes . codes came back in 30 miles. codes seemed to set under more than half throttle load making me think it was a MAF sensor . but today it set on steady cruise 4 miles into drive to work.
should i clean throttle body and add fuel system cleaner and go from there?

 

[gmtech]

re smoked intake system with power smoke machine. found smoke coming from EGR solenoid.. thought i read somwhere that this is normal? is that true Discostew? cleaned throttle body also but it was pretty clean already. installed bottle of fuel injector cleaner also.

 

[Howski]

IIRC that gasket on the EGR pipe can get buggered up and can leak. Often after people do the thermostat replacement

 

[gmtech]

which gasket? could you link a picture? thanks mine was leaking from where the solenoid on top bolts to main EGR.

 

[Dogbreath077]

Use a piece of vacume hose to find intake and exhaust leaks. Put a piece of thin brake line on the end of it, and then put the other end next to, not in, your ear. Run the metal tube around and all over the engine and when you get near the leak, you will hear it loudly.

 

[gmtech]

how is that going to find what a smoke machine wont? a hole big enough to whistle loud enough for you to hear over the engine running is going to let a lot of smoke out with a smoke machine. i have been using a smoke machine like this https://www.grainger.com/product/80...VYxStBh27Iwb6EAQYASABEgIq2PD_BwE&gclsrc=aw.ds

it makes a lot of smoke...

 

[discostew]

i have been chasing this for the 2 months ive owned this. smoked system found cracks in intake duct. replaced with landrover part from british parts of utah. cleared code. made it 3 drive cycles and 50 miles. codes came back. removed and cleaned MAF. cleared codes. codes came back in 4 miles. replaced MAF and air filter cleared codes . codes came back in 30 miles. codes seemed to set under more than half throttle load making me think it was a MAF sensor . but today it set on steady cruise 4 miles into drive to work.
should i clean throttle body and add fuel system cleaner and go from there?

Yeah. They get restricted. Since your a GM guy I would maybe use a couple small bottles of top engine cleaner and fuel thru a injector flush canister

 

[gmtech]

k thanks. also me and some other techs were thinking on it. would a pcv that is sort of stuck cause lean codes? it goes to the duct and if it were leaking it would be internal so you would not see smoke. it is an 08 with 160k on it and i have no idea if it has ever been replace.

 

[gmtech]

after reseting fuel trims. codes have been gone for over 200miles. thanks for the help! the fix was either the air duct between the air box and throttle body. replaced with new. or the mass air flow sensor which was replaced with new denso one.