NefMoto

So against the general opinion of this here forum, I've been running MAFless for the past year or so. My car is Wideband 4B0906018CH so it's closed loop all the time.

I've decided I've had enough of the MAFless game, as I'm not sure how to go about removing it the "right" way. I zero'd a few codewords and FF'd a few pressure ratio maps, and it runs great when its warm and at WOT. Cold starts is another issue though, with AFRs dipping to 10.5-11ish for no reason and then slowly climbing back to a reasonable 12-14. I'd rather go back to MAF now.

Problem is when I plug my MAF in, the AFRs go >18 and it idles like shit, obviously. I logged it at idle, and have attached the logs here. MAF airflow is ~6 g/s with TTQS's fully defined TT225 MLHFM, and ~4 g/s with another MLHFM I got from an OTS tune that calls for the TT225 housing.

No boost leaks or leaks between MAF and turbo. Intake consists of a 3 in U-bend off the turbo to the TT225 MAF housing with a AEM air filter on the end. KRKTE and TVUB also attached for my shitty deka 630s.

Should be trivial to fix by only watching short term fuel trims.

I will go check. TVUB too low?

Care to clarify?

I adjusted TVUB to the values located in this thread (http://nefariousmotorsports.com/forum/index.php?topic=1834.msg17780#msg17780)


Now it starts nice, and holds an acceptable AFR for about 5 seconds. Then it just sweeps slowly to 18. What bothers me is that the logged wideband o2 voltage stays at ~1.49 volts, and the logged current AFR is 14.7, even when my UEGO says -- from being too lean. I have had a B1S1 Malfunction in circuit DTC since I coded out my secondary o2s via ESKONF, but is it possible my primary o2 is actually dead?

Block 99 in VAGCOM says o2 control is off. Attached is a log with the changed TVUB.

I'd definitely check or replace your primary o2 sensor. That doesn't sound right.

Thing is, with the MAF unplugged, o2 regulation turns on and it holds a consistent AFR. I did some logging the other day for KFLDRL calib, and logged current AFR matched requested. The o2 voltage matched as well.

There really isn't much to MAF based fueling.

KRKTE, TVUB, KFWWL and the various MAF maps...

I believe I have it figured out. And it has to do with another piece of hardware that is a big no-no on this forum. Ughhhh I guess it's time to redo my hot side piping again.

BTW, The car drives fine, just doesn't idle well. And when it warms up, o2 reg kicks back on at the STFTs are +25% at idle.

Does it make WHOOOOOOSSSSHHHHH noises?

DING DING DING

Maybe I should say fuck the DV and go all out with a blow through MAF

Meh.

How much power are you planning on? I wouldn't bother blow through unless it was necessary. Too much of a PITA. Keep it simple is my motto.

Hoping for ~450whp this summer after I build my stroker engine. Shouldn't be too hard to plumb in my DV again though.

I have an AEG crank sitting in my garage. Just sayin'.

I'll keep it in mind. I was just gonna snag one from a junkyard for cheap. Not tryin to lowball ya.

If you're local, you can have it. It's still in the shortblock so no damage.

 :DCheck you email, sir.