I have been trying to diagnose my lean condition for a couple months on my car, and am about to start shotgunning parts.

Car is stock air intake, and just has catback exhaust.

I got a Diablo Sport tune for fairly cheap and then was working with a Diablo "tuner", I would drive 500 then log info and send it to him, he would modify and send back. ETC....

At the first couple logs I was running a tad rich he had said, then after a couple more logs he said I was extremely lean.

He continued to make richening adjustments on the tune, while I looked over the car.

I have tripple checked all intake hoses, MAF (cleaned), tubing for leaks. I used a SmokePro with 10psi in the brake booster line for 15 minutes to look for intake leaks, nothing.

I had the front pipes welded onto the X-pipe instead of bolted and the exhaust looked over by a shop, and myself.

I have had the "FINAL" tune uploaded on the car for about 2000miles and still I experience +9 - +13 % LTFT's and my STFT's look normal with the O2's. The car has never thrown a code but it makes me nervous getting into WOT being lean, if it is above 85 OAT I will get a bit of pinging as well.

But if I upload any tune (any of the 4 he has made) as soon as I drive the car it feels a lot snappier and will get my michelin pilot sports spinning through first gear. After I log miles on it something changes, and it no longer feels the same.

I have been searching for local HP tuners and have had zero luck, I do not want to pay for a big shop to take my money and kick me back out the door either.

On a side note, when it is cold and I leave the driveway if i give it a bit of load on the accelerator it will stumble just a bit, until it warms up.


HELP ME!

 

All you have is a catback, I would just flash back to the factory tune. You're only giving up 10-15hp anyway.

 

I plan on switching back to see if it gets better. If not then I will at least know its not the tune, maybe next I can try unplugging the MAF.

 

If you have +13 LTFTs then you are not running lean at WOT, in fact you are probably quite a bit rich. At WOT, positive LTFTs are added on top of the existing fueling...so there's no way that you're running a dangerously lean conditions with an extra 13% fueling on top

 

Ok that makes sense, I know as far as tunes go that WOT is different than normal cruising, correct? I should clarify that I am logging these lean LTFT's driving from A to B in closed loop all RPM ranges, stop and go traffic. Maybe 65% highway time and at 2000rpm. I was questioning in my original post if I am lean at WOT, I haven't logged much WOT runs to dig into it but I am experiencing pinging.

My understanding is that I should be within +/- of zero with my LTFT's. LTFT's control the STFT which modulate up and down (enrichen/lean) past zero to satisfy the o2 sensors which satisfy the Cats. When my LTFT's are registering +12% then that is a lean condition and the computer is compensating 12% of fuel to satisfy my STFT's correct?

I am looking for some advice on the situation:

1. I will scrap this tune and revert to stock and see if that helps.
2. Why when I upload a tune (anything) the car drives like a demon on the loose (no pinging or anything) for a very short period of time, then falls flat...
3. A few stumbles when in OPEN loop, and the LTFT's running lean -- MAF related, how can I effectivly check this?

Any thoughts, input?

Thanks so far! As you can tell I am a bit of a newb, I appreciate the time folks!

 

Sounds like you need to get a real tune and possibly a wideband to actually monitor the fueling past normal driving.

Otherwise, it's like pissing in the wind with what adjustments to do.

 

Ok thx.