Chevy pickup problem

IMCA38 · Jan 8, 2012

Any Chevy techs here that can help me out?
I have a 2005 K1500 with 5.3L V8. (code T if that matters)
A while back, I had the check engine light coming on under hard acceleration.
I scanned for codes and got a code for MAF problem (101 I think). I checked for air leaks, cleaned the MAF and cleaned the K/N filter. Still had the light, so I replaced the MAF. That took care of the light coming on under acceleration.
However- A few days later, the light came on again while sitting at a red light idling. Re-scanned and now shows code 171 and 174 for lean on left and right. After reading some Chevy forums, it sounded like an intake gasket leak might be the problem. I did the carb cleaner test up and down the intake and didn't find anything.
Given this information, are the upstream oxygen sensors the likely culprit now?

Thanks!

Todd

WilliamBos · Jan 8, 2012

What does the exhaust look like?? Smoking black? Is the mileage terrible??

Lost sensor 1, Bank 1 (front oxygen sensor, drivers side.) and it took the Cat out with it. Got a new Y-Pipe covered by Federal Emissions warranty, via GM.

Maybe get it to a dealer, and have the diagnostic done, just state you want a print out, and no repair done. That Y pipe was $1K.

Mine is an 04, same VIN code 5.3L.

IMCA38 · Jan 8, 2012

I haven't noticed any black exhaust. Mileage may be down a little, but not much (1 MPG +/-) . Seems to run OK also.

WilliamBos · Jan 8, 2012

ok. When I lost sensor1, it was dumping raw gas into the cat, smoking like an old diesel, and burnt the cat out.

A tank of gas did not last too long.

Dmace · Jan 8, 2012

O2 sensors rarely go at the same time like that and if they did, you would see a code for at least one.

Since both sensors are reading a lean condition then the problem is something that affects the engine on both banks. I think it's still a MAF sensor or intake leak. I've received bad MAF and other electrical parts from stores before.

If you have the old MAF, plug it in and see if you get the same symptoms as before. When is the last time you cleaned the K&N? Is it possible you over-oiled it?

WilliamBos · Jan 8, 2012

To add what Derek suggested, if you have the factory airbox and filter, put it back in, until you resolve the issue.

Diamondpilot · Jan 8, 2012

I saw this on a V8 Lincoln Aviator. Ended up being a combination of a bad PCV valve hose and a bad hose going from the break booster to the intake.

Chris

CLinton_in_FL · Jan 8, 2012

My guess is the intake gasket. I had my engine light come on every winter because of the cold. Replacing it is not that bad. Or you can just wait until the summer, and it will go off

Stihlrunner · Jan 15, 2012

You might look up Technical Service Bulletins for that. I remember seeing several on aftermarket oiled filters.

Also, throttle body butterflies can get regularly gummed up and wont close completely causing and air reading problem. Believe there to be a TSB for that also.

CowboyRon · Jan 15, 2012

I had one of those codes showing maf, and it was my fuel pump. We put a pressure gauge on the fuel line and it wasn't getting enough fuel.

Dana Warner · Jan 15, 2012

Sounds like a MAF problem or an intake leak after the MAF. Low fuel pressure is easy to check too.

flusher · Jan 15, 2012

Dmace said:
O2 sensors rarely go at the same time like that and if they did, you would see a code for at least one.

Since both sensors are reading a lean condition then the problem is something that affects the engine on both banks. I think it's still a MAF sensor or intake leak. I've received bad MAF and other electrical parts from stores before.

If you have the old MAF, plug it in and see if you get the same symptoms as before. When is the last time you cleaned the K&N? Is it possible you over-oiled it?

K&N is touchy on this subject

K&N Response to Mass Air Flow Sensor Concerns

yasureyoubetcha · Jan 15, 2012

My friends pickup{also a 2005} did the same thing after I installed a K/N filter system for him, s.e.s. code said lean on banks 1&2, put the original filter back in and no more problems. It did run ok tho...

kf4uda · Jan 15, 2012

Odd timing for this post. I have a '03 GMC Sierra with a 0171 code on it. I am running a K&N filter on it as well. I just finished cleaning the MAF with CRC Mass Air Flower cleaner and then reset the code. I have had this problem before so I am fairly confident it will fix it.

I think I am going to dump the K&N filter and go back to a stock filter. I am not necessarily bashing K&N as it could be a case of me over oiling the filter.

timswi · Jan 15, 2012

I've run K&N's in my last 4 GM pickups and never had a problem...Odd though that it appears that the dealer removed the K&N warning sticker when I had it inspected...Was going to call and complain, but I forgot about it...I'll argue with that tech anyway, he put a 12/12 inspection sicker on it with a 12/13 emission sticker...I'll argue eyesight

I've had one in the wife's Hummer for 3 years and never had an issue.

Diamondpilot · Jan 15, 2012

timswi said:
I've run K&N's in my last 4 GM pickups and never had a problem...Odd though that it appears that the dealer removed the K&N warning sticker when I had it inspected...Was going to call and complain, but I forgot about it...I'll argue with that tech anyway, he put a 12/12 inspection sicker on it with a 12/13 emission sticker...I'll argue eyesight

I've had one in the wife's Hummer for 3 years and never had an issue.

I am with you. I have had them on 15 or so Fords, 1Nissan, and 1 GM with no issues. Some were K&N and some were other brands such as MAC.

Chris

lostcause · Jan 17, 2012

i used to have a 2000 chevy 2500 crew (classic style) with a 5.7 that i bought used in 2002 from a gm dealer. it had a k&n filter on it when i bought it, and I had used them before on bikes & atvs with good results, so i left it on. a few months later i started having issues with it stuttering under load, like when pulling out into traffic with several thousand pounds on a trailer behind it.

i took it to the selling dealer and explained the issue, and eventually they were able to reproduce the problem so they knew i wasn't crazy. the problem was that they couldn't figure out what was causing it. that vehicle probably didn't have anywhere near the onboard diagnostic abilities and sensors as the newer ones, so it wasn't throwing any codes to lead toward the problem. eventually, after a few calls to gm tech, they got a guy who out of the blue asked if it had a k&n filter. that ended up being the problem. apparently, small amounts of oil was bleeding through the filter and adhering to the mass airflow sensor, then tiny particles of other contaminants adhered to the oil coated wire in the sensor.

this coating obscured the wire so it was getting an incorrect reading and adjusting the fuel mixture improperly. after cleaning the mass airflow sensor and replacing the k&n with a stock style filter things were all better. as another poster said, it's not a complaint against washable filters - it could have come from over-oiling of the filter, or maybe even a lack of maintenance. i've used them before and i'll use them again, but probably not in a fuel injected vehicle. i don't need the extra airflow in a stock vehicle and i don't think long term reliability will suffer from a stock filter, so for simplicity's sake i'll keep going with the paper elements.

deerehunter/operator · Jan 19, 2012

At our GM garage, we see problems fairly often with K&N filters coating MAF sensors with filter oil. Cant count how many times especially on the Duramaxes. Put a stock filter in it and clean or replace MAF again.

murphy1244 · Jan 19, 2012

The reason your showing a lean condition is the K& N filter allows more air thru. On my 70 chevelle I had to rejet and reset idle screws.

kf4uda · Jan 20, 2012

So far cleaning my MAF has worked. The code has not come back but I have only put about 80 or so miles on my truck. I have not done anything with K&N filter yet. I may just clean and re-oil it, taking a little more care this time and not over oil it. I still think that I over-oiled the filter.

Not related (except the same truck) but looks like I will get to install a new water pump tomorrow. Making noise and leaking from the weep hole...oh joy!

How is the problem coming with your truck Todd?