Random, inconsistent P0174
 

Tripped my second PO174(system too lean bank 2) code in 13 days last night. I drove to a football game in the late evening and parked it for a few hours then tripped the code when I started it up to leave. This happened on Oct 3rd with a similar situation. Drove it for a while, parked it, ate dinner at a restaurant and then started it up that night to go home and boom P0174 pops up. BOTH times I stopped my car, cleared the code and then restarted and continued driving for 10-30 miles(depending on the night) and it never came back on.

Inbetween Oct 3rd and last night I went to the dragstrip and ran two passes without any codes at all. In fact i've ran it harder within the last two weeks than I ever have(I drive my car every day). If I was really running lean all the while I feel as if I would have either blown the rotating assembly or burnt a piston. No modifications or abnormal service has been done on my car in ~13 months. Any ideas?

Same possible causes as P0171. Where it is just on bank 2, look for things that affect just one bank--exhaust leaks come to mind first as they will make the PCM think the mix is lean when it really isn't...

Ok so I filled up this weekend and noticed MPGs @ 17. Ruh roh. I've never seen it below 19MPG and thats on a hard-driven tank of gas which this tank was not. I think this kinda confirms i've got an A/F mixture issue. I thought the codes might have been weird flukes but theres something wrong.

So I have a question. I've only gotten the code twice since October 3rd. Does this mean the problem is only popping up for short periods of time, or that its actually there the whole time? Why wouldn't the ECU throw up a CEL right after I clear the code if the fuel trims are still at their limit and the problem still existed? Why wont it come back on yet my ECU is dumping fuel?

Also.....considering my ECU is dumping fuel(low MPGs) and my mixture is still coming out lean enough to trip the CEL does this leave any other possibility OTHER than an exhaust leak or bad o2 sensor? Is it possible that I have a problem thats making both banks run lean but is only engaging a check engine light on one bank? What side of the engine is bank 2?

Will a wideband A/F kit help solve my problem? I assume that if it is an exhaust leak the A/F gauge will confirm the mixture as lean yet I will continue to get horrible MPGs and presumably eventually another P0174. If it is a bad sensor the A/F gauge will show normal, acceptable mixtures yet the ECU thinks its lean based on bad reading from the o2 sensor? I've been wanting to get a wideband setup as is and now seems like a good time to do it?

I was looking at this kit, would this be everything I need to read A/F?(No tuning accessories/capabilities needed)

What is the difference between the MTX-L and DB Gauges. Just the gauge?