Scotty,
I have a 2010 gmc canyon with the 3.7 liter inline 5 cylinder engine. I bought it used with 150,000 miles. Love the truck, but I have a P0171 code that pops up randomly. The truck runs really well, so I clear the code and it'll stay off for a month or so then pops back up. I replaced the vacuum hose under the resonator box. Didnt help. Cleaned the Mass air flow sensor. No change.
It does have the K&N cold air intake on it. It came with it. I've checked all connection points for possible leaks and found none.
LTFT is showing 22-25% so its running lean, but i cant seem to figure out why.
Other than having crappy MPGs, is this dangerous to drive?
No emissions/smog test to worry about here.
Another thing that's odd is I smell what smells like exhaust through the air vents as soon as the truck starts, but its just for a second and the smell is gone.
This is weird to me. Any ideas?
LTFT is showing 22-25% so its running lean,
positive numbers means it's running rich.
Look for exhaust or EGR leaks.
I would ditch the K&N until you figure this out to make troubleshooting easier.
If the fuel trim is positive, it is adding fuel to compensate for a lean mixture. So the positive indicates it is running lean, while negative indicates running rich. That’s the way I learned it.
oops! you're right. I had a brain fart there.
I meant to say the computer is ATTEMPTING to enrich the mixture to compensate for the lean condition. Which would explain the P0171 lean bank 1 code.
Derrrr. {pear}:exhausted:
That might be a clue that it's only on one bank. Check for vacuum leaks on that side.
Other than crappy fuel consumption, is there anything wrong with driving it this way? Like i said, it only trips the code roughly once a month, but it runs perfectly fine. I cant find a vacuum leak any where.
yeah you'll wear our your engine and catalytic converter quicker.
So let me ask this. Regarding the quick smell of exhaust on startup, and I've read that exhaust manifolds are prone to cracking in these trucks, could that cause the leak?
yup
I put my money on the K&N causing the problems, especially if you oil the filter. The really screw up the MAF sensors, IAC, TPS and throttle bodies.
