Is your maf back in the exact same position in which it was tuned?

 

All the pieces and couplers are in the same location. I'm sure there was a tiny bit of shifting around with the adjustable slack in the couplers ... but still in the passenger fender well with same bends before and after.

 

Hmmm that seems odd, what side is your wideband on? Drivers or passenger? I would pull all those plugs on that side make sure they look okay.

Maybe the sensor itself is bad?

 

I think 12.3-12.6 AFR seems pretty good. You're still a bit off of stoich. What are you worried about. Also, you said you recalibrated your wideband... maybe nothing has changed, just the number you're seeing.

 

I don't feel safe with a 12.5 A/F on boost ... especially @ 7K+ RPM. N/A I'd be fine.

 

12.5 is nowhere near lean, especially at only 8lbs of boost.

 

temperature changes?

 

I wouldnt go WOT if I saw my wideband read 12.5... **** that.

 

Clean the maf and connections. Make sure its clocked the same as it was before. Clocking the maf can have a HUGE impact on the tune.

 

I'm positive I must've rotated the MAF Housing but at this point I have no clue what it's original position was. Do you just suggest rotating it 90 degrees, testing and retesting?

My wideband still reads 14.6/14.7 @ idle so it seems like it's reading right ... but I suppose I can find someone else with a wideband to test. If it means anything, I'm running an almost new Innovate Digital MTX.

 

12.8 is pretty lean for a FI car. Its like saying "she only has a little herpes"

12.5 is ehhhh

From my experiances and from what iv seen. Aftermarket wideband sensors are normally junk.

Iv seen them as far off as 1.0 which can be life or death at times.

Maybe its your sensor. Anyone you know have a spare wideband to stick in it and verify.

 

There is not a real tuner in this country that will tune a pump gas boosted car to mid 12 afr at WOT. Everyone must be crazy when they say take your foot off when you see the wideband go into 12 at WOT.

 

Did you have a boost leak when it was tuned? If you adjusted the fittings and now have no leaks it can lean you out, but if you still have the same amount of boost that would not be the problem. Just throwing some more ideas out there.

 

Hahaha. I thought that'd throw you off a bit. It was in my fathers experimental aircraft. Believe it or not, there's about 10 airplanes flying around with my enignes in them... somewhere. I lost track of most of my customers when I got out of that business. They were cool, but dangerous.

 

You dont remember which direction you had to plug and unplug the maf from? Come on THINK HARDER. If not then you could try rotating the maf 90 degrees at a time and see if it richens up a little... If you clocked the maf that is probably the problem. I'm guessing your running a LMAF in a blow through app? or Some sort of standard housing maf in a blow through app? Either way draw though and especially blow through, changing the maf clocking can affect the AFR. Obviously its going to read normal during regular driving because its in closed loop... but I bet the fuel trims are further off than normal.

 

Fuel pump starting to go bad?

 

Reason I'm nothinking it's fuel delivery is the A/F goes to 12.5 immediately once WOT. So even @ 3500RPM flat through 7000. Bad pumps would just start to lean out at upper RPMS. Plus my fuel pressure and pump duty cycle both look normal.

Boost Leaks ... while I can't say I had 100% no leaks during tune ... my Boost gauage shows aboutt he same psi. (It's hard to tell if I picked up an extra 1psi due to the gauge's range)

I'm gonna take the advice put out earlier in the thread and try fiddling a little bit with the MAF rotation today. See if that helps any.

 

a leak after the maf will show lean at idle and rich at wot. any leak before the maf wont really show any change to your af. also check to make sure your maf is not maxed. max maf counts is 1023

 

Was that 12.5-13 on the ground? At that altitude the A/F will be way different than on the ground.
I would NEVER let a F/I car leave the dyno at that A/F.

 

I wouldn't trust it, especially with 10:1 compression ratio. Try reclocking the MAF a little at a time.

 

my tuner told me mine should stay 11.1-11.3/(11.5 tops), he clearly and made a strong point to say "if you ever see your a/f ratio in 9's or 12's get the hell off the gas pedal cause something is wrong!"

 

Inj! less lkeley but plausible

 

This got brought back up but I'll update it for future searchers. I forgot that I had relocated the IAT sensor from pre-blower to POST-blower. It was enough of a difference to throw it all off. I have since gotten a new tune and it was sitting pretty since.