Drew24

P0171 says my car is running lean and left fuel trim bank 1 don't know what that could be help please

Injuneer

The PCM has detected a lean condition in the Bank 1 exhaust, and has used the long term fuel corrections (BLM's) to add extra fuel. The average of the BLM's for the various operating cells has exceeded 22% extra fuel. That's a lot of fuel to need, and the PCM is alerting you to look for the problem.

This could be a "true" lean condition, or it could be a "false" lean condition. You have to figure out which one it is. First thing to do is use scanning software on it, and pull the BLM's. Look at both left and right banks of the engine, to determine if you have a problem affecting only Bank 1, or in fact affecting both banks of the engine. The Bank 2 BLM's may also be elevated, but just not quite enough to set P0174.

If both banks are high, you could have a problem like low fuel pressure, a large vacuum leak, air bypassing the MAF sensor, or a faulty MAF sensor. If the problem is not affecting Bank 2, most of those problems can be ruled out, and you have to start looking for problems that can only affect one Bank of the engine.

Common causes of a "false" lean condtion are misfires and exhaust leaks before the O2 sensor. Or a faulty O2 sensor or problems with the wiring (are you using extensions?).

One relatively rare cause of a lean condition can be contaminated fuel.

Start with a scan using something like AutoTap.

Drew24

What can I do to check the right bank so I can rule some things out

Injuneer

Data log it, as already suggested above.

If you want to guess... look for exhaust leaks before the left bank O2 sensor, look for misfires on the left bank, and look for problems with the left bank pre-cat O2 sensor and harness wire.

Drew24

Ok well I put it on a scanner and this it what it read out
1.57% engine load
226f ect
21.09% short term ft bank 1
25.00% long term ft bank 1
13 to 15 % short term ft bank 2
25.00% long term ft bank 2
4.6 psi map
630 to 670 rpm engine speed
15 to 16.3 spark
170f Iat
0.62lb/m maf
0% tp angle
115 to 485Mv ho2s bank sensor 1
15 to 65mv ho2s bank 1sensor
135 to 580 ho2s bank 2 sensor 1
100 to 615 ho2s bank 2 sensor 2
This is at idle and that's what the scanner gave me anything look unusual

Injuneer

You got a massive problem that is affecting both banks of the engine, at least at idle. Check the fuel pressure. Check the MAF sensor. Does it reak of fuel? If not, its a true "lean" condition, and you need to fix it before putting any appeciable mileage on the engine. Probably some of the worst numbers I've ever seen.

Its adding the maximum possible amount of extra fuel using the long terms (25%) and then having to bump the short terms up by another 13 - 21% to add even more. Its pouring fuel in, and (recognizing that your single snapshot doesn't provide much info) the O2 sensors are still spending a lot of time on the lean side.

The engine is running pretty hot at 226*F, and the IAT value of 170*F indicates the underhood temps are excessive and the IAT sensor is heat soaking badly. I've never seen anything that high for the IAT in hundreds of data logs that I've reviewed for people. Something is screwed up, or you live in Death Valley. May account for the low spark advance at idle. I'd expect to see advance in the range of 18-22deg.

The 4.6psi MAP reading is unusual. Most systems report in kPA or "Hg. If your barometer is about 14.5psi, it makes sense though. Are you sure its calibrated in PSI?

Drew24

Yeah that's what the scanner read and yes it smells like raw gas and the temp I live in vegas and that was the reading of it warmed up at idle I don't really know what to do I'm doing to check the fuel pressure but should I replace the maf sensor and the o2

Drew24

Ok I got the fuel pressure tested and it was about 56 psi when car is off and 50 psi at idle don't know if that's good

Injuneer

Way too high... but that is totally inconsistant with the elevated BLM's. Should be around 36psi at idle with the vacuum compensation line off, 43.5psi with the vacuum compensation line on.

Excessive fuel pressure would make it run rich, and that would cause the PCM to reduce fuel, not elevate it. If it smells pig rich, its a "false" lean condition.

Drew24

Hmm well I cleaned the maf sensor and cleaned and oiled the knn filter and sea foamed the car the check engine light went off and now its back on for lean in bank 1 and it keeps going on and off the more I drive it turns off