Lean codes

[Chris111179]

I’m getting codes P0171 P0174 both banks lean, all off a sudden. Long term fuel trims are at 24 ish %, I have checked for Intake leaks. And when doing a log I noticed the MAF reading of .55-.61LB/M. So I cleaned the maf, no change. Does this seem like a low MAF reading?!
Car runs like normal with no seemly ill effects.

[Chris111179]

Update; I only get the codes at idle or at very low throttle input. When cruising down the interstate my LTFT are around 10-15+. Still lean I believe. But correctable. This all started about 50 miles after I changed the radiator/cleaned the air filter. The filter was very dirty. Currently I have a Vararam intake (verified “strong” MAF), Rod Mod intake, and Borla cat back exhaust. Checked for exhaust leaks, none. Plugs look normal (caramel brown on the insulator). Any thoughts?

[morepowerjoe]

I'm assuming your car is tuned?

[Chris111179]

Originally Posted by morepowerjoe

I'm assuming your car is tuned?

Negative. Stock tune, was running okay for like 5k+ miles.

[TheBrightSide]

I forget the exact CEL code number, but it was like P013X or something, and usually comes on BEFORE the P0171/P0174 CEL codes, depending on the bank(s).

I personally had a P0174 code constantly, after clearing the initial P013X CEL code and driving the car. Everything seemed fine, except the lean CEL code and mileage dropping pretty significantly, about up to a loss of ~4-6 MPG.

However, this was particular to my situation after months, when the P013X CEL came up constantly and did not go away; and would trigger the P0171 code if I cleared that and KEPT driving (or keep the engine on). Ended up being the bad primary/upstream O2 sensor for that bank. Took out both sensors, and the bad one was covered in tons of black soot.

I'm also tuned and have long tube headers; where I see lots of bare metal header upgrades, typically heat-soaking old primary O2 sensors and killing them off. I also had primary O2 sensor extensions, which I thought went bad; but I ended up replacing the extensions as well, and the sensors; which solved my problem.

I'd probably clear the code and keep driving, and cycle the car and see what codes come up and when. I haven't really messed with my mostly stock car, so I can't say the same if you're heavilly modified. The only vacuum things that I've messed with, are the intake manifold, some of the PCV lines from the engine valve covers and engine valley cover (LS3); and I even checked my MAF sensor and intake/airbox, which were all good.

[morepowerjoe]

The first thing I would do is check your fuel pressure. You can either check it with hp tuners, with a manual gauge on the port on the fuel rail, or with a good scanner. I don't know unfortunately which type of scanner could check fuel pressure but I'm sure there's one out there. The fuel pressure should be around 58 psi. If that checks out ok then you need to make sure your maf is all good. Make sure it's plugged in all the way, the wires don't have any cuts, and maybe
get some of that maf cleaner and spray it down with that stuff. Let us know what you find.

[Chris111179]

Originally Posted by morepowerjoe

The first thing I would do is check your fuel pressure. You can either check it with hp tuners, with a manual gauge on the port on the fuel rail, or with a good scanner. I don't know unfortunately which type of scanner could check fuel pressure but I'm sure there's one out there. The fuel pressure should be around 58 psi. If that checks out ok then you need to make sure your maf is all good. Make sure it's plugged in all the way, the wires don't have any cuts, and maybe
get some of that maf cleaner and spray it down with that stuff. Let us know what you find.

Copy that, fuel pressure is reading 58psi on the scan tool, doesn’t seem to move at all even under acceleration. Got some
Of the MAF sensor cleaner, followed the directions. And still getting high readings unfortunately. Wiring to it all looks intact going all the way to the harness.

[Mouse330]

Disconnect the MAF and see what your fuel trims do, I would lean towards the MAF is NG. Do you have another MAF you can try for testing?

[Chris111179]

Originally Posted by Mouse330

Disconnect the MAF and see what your fuel trims do, I would lean towards the MAF is NG. Do you have another MAF you can try for testing?

What should I expect with the MAF disconnected for fuel trims? Will report back!

[Mouse330]

They should be close to normal +10 -10 0 is ideal

[Chris111179]

Originally Posted by Mouse330

They should be close to normal +10 -10 0 is ideal

Okay so I removed the connector for the maf. Fuel trims are now 4-8. I think you found the issue. Ordered another MAF, should be here Thursday. I’m thinking the lean condition makes sense as I have an exhaust, intake, and the rod mod intake.

[InFiD3ViL]

Just in case that isn't the issue - I also have a Vararam and the plastic on the neck that meets the throttle body/silicone coupler has a 1 inch crack on mine. I sealed mine with some Flextape (externally) and its not causing any further issues. Anyhow, it wouldn't hurt to take a look at yours and make sure the plastic isn't cracked anywhere.

Good luck getting this sorted out

[Mouse330]

Originally Posted by Chris111179

Okay so I removed the connector for the maf. Fuel trims are now 4-8. I think you found the issue. Ordered another MAF, should be here Thursday. I’m thinking the lean condition makes sense as I have an exhaust, intake, and the rod mod intake.

I think you should be good

[Chris111179]

Originally Posted by Mouse330

I think you should be good

Took me a bit to get the new sensor in. But I’m back in business. Runs great again. Thanks for your help!!