Bought Another Mustang!!! Questions/concerns!

Hi all, so I sold my fox a few months ago... And now, I bought a 2006 mustang gt drop top! 5 speed (manual).

So a couple of things, it has a c&l CAI, hurst shifter, and what looks like borla stingers (axle back).

The car had been sitting for a year(before I bought it)... Anyway, I picked it up.. Drove it. Pulled hard a few times and at first noticed it wasn't overly impressive. Anyway, after driving it 10-15 kms I parked it... Started again after and it showed better performance... After parking it another spot for a bit and getting in, once I started it the check engine light was on. No diff in sound, idle, driving or anything. I put my code reader to it when I got home and it gave me two codes...
P0171 system too lean bank 1
P0174 system too lean bank 2

So I deleted the codes and drove it, pulled hard off a launch and was definitely impressed with the performance(compared to when I had just picked it up)...
Anyway I'm curious to know why it through those codes and what that means... I do not know what tune it has or anything, nor did it come with a handheld tuner. Any suggestions folks???

SpartaPerformance said:

Could be a vacuum leak.

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Hmm, thought of that, but wouldn't it have a rough idle or anything with a vacuum leak? Which lines should I check?

Red_LX said:

If it has a C&L CAI it most likely has a tune. Try running some 91 or 93 octane through it (whichever you can get in your area) and see how it does, it might have a 91/93 octane tune on it.

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I did put some 91 in it. But, who knows what was ran the last 8 months... I'm goin to fill some 94 in it and throw a fuel system cleaner in it!

Svtpilot said:

Is it possible that the factory tune was reloaded before you bought the car? If you have the C&L Race intake or the Street intake with what they call the "no tune option calibration insert tube" removed, a tune is needed. The factory tune will cause a lean conditioned. Regardless of the cause I wouldn't drive it to much until you get it fixed. Driving with a lean condition could damage your engine. The other thing I would look at is you said that the car sat for a year. If it did the battery probably died so the computer may need to relearn the idle and and fuel trim strategy. The procedure is in the owners manual. Like I said though don't mess around with this if you have to bite the bullet and pay someone to fix it, then do it. You can cause serious internal damage driving with a lean condition.

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Yeah, I don't know. I cleaned the maf sensor, checked for vacuum leaks... Nothing. Drives fine, no pinging. But, I'm going to get the car re flashed from ford to factory settings and then right away I'm getting a tuner and throwing a tune on it. Not risking it. Just sucks because I didn't expect to spend an extra 600 some off dollars on the car right off the bat!