Lean Misfires at 2700-2800 rpm

[badass3000]

Originally Posted by TurboBob

So, its just lean then.......

My guess is that its such a narrow window, that its hard to tune out because the ECU re-learns the tune.

I have a few ideas. I need to get the AC/Alternator idlers changed before I can do much more testing, but I think I have a solution.

Bob

my ECU cant learn , No O2 sesors

[ProwlerGT]

Originally Posted by badass3000

my ECU cant learn , No O2 sesors

Not to hijack the thread, but does that hurt your gas mileage much?

[badass3000]

no. it helps. ALOT! 30+MPG

[TurboBob]

The Pro has lean cruise mode, so you can set it to lean out while cruising.


Bob

[DoctorDex]

Bob, I'll get you some more logs if you need. I don't have MAP logging capability anymore (MAP sensor crapped out on me), but I can get you any other values you need. Are there any specific "logging conditions" you're looking for?

With regards to my testing, let me do another more conclusive test before we draw conclusions. I'll finally be home on Saturday (been gone since June), so I'll post my results sometime in the afternoon.

Originally Posted by TurboBob

So, its just lean then.......

My guess is that its such a narrow window, that its hard to tune out because the ECU re-learns the tune.

From the preliminary test, its looks like as if the ECU leans the mixture out from the 2500 - 3000 rpm range and even though you try and compensate by adding more fuel, the ecu "forgets" to inject fuel, on both banks, most often at an rpm slightly higher than 2700, but occasionally anywhere between 2500 - 3000rpm. Hence, the miss. It doesn't seem to be related to ECU learning because like badass said, it does it whether or not the O2 sensors are hooked up and it also does it at WOT. I have no idea why this is and I can't explain it.

Originally Posted by TurboBob

I have a few ideas. I need to get the AC/Alternator idlers changed before I can do much more testing, but I think I have a solution.

Interested. Are you willing to share any of your ideas?

Edit: Bob, can the MAFTPro be used a drop in replacement for the MAFTranslator? Ie. I can keep the GM MAF and the MAFTPro will work as a "translator"? Does wideband tracking work if the MAFTPro is in translator mode?

[TurboBob]

Originally Posted by DoctorDex

Interested. Are you willing to share any of your ideas?

Bob, can the MAFTPro be used a drop in replacement for the MAFTranslator? Ie. I can keep the GM MAF and the MAFTPro will work as a "translator"? Does wideband tracking work if the MAFTPro is in translator mode?

At the moment, the fix is a software tweak to the Pro. I am positive I can fix this issue, but the exact strategy is still being worked out.

The Pro can run as a translator, and works very well as such. The Pro is not an exact "drop-in" because of the wiring differences. But with a 2G MAF adapter (2G DSM = 3S) and a boomslang install harness its pretty much a plug-and-play affair.

All of the features work in Translator mode.

Bob

[ProwlerGT]

So are you guys saying that the Pro is the problem or the Pro can be a workaround?

Dex - Have you tested your alternator at at least 2 auto stores? I say at least 2 cause I once tried it (off the car) at 5 different stores (theres a thread about it) and I got at least 3 different results.

Also, if your MAP sensor crapped out on you could that not be a cause for the problem or what am I missing there?

[TurboBob]

Originally Posted by ProwlerGT

So are you guys saying that the Pro is the problem or the Pro can be a workaround?

The car is the problem, the Pro is the solution.

Bob

[ProwlerGT]

Originally Posted by TurboBob

The car is the problem, the Pro is the solution.

Bob

Robot Voice: AFFIRMATIVE.

[DoctorDex]

Originally Posted by ProwlerGT

Dex - Have you tested your alternator at at least 2 auto stores? I say at least 2 cause I once tried it (off the car) at 5 different stores (theres a thread about it) and I got at least 3 different results.

Also, if your MAP sensor crapped out on you could that not be a cause for the problem or what am I missing there?

I haven't checked my alternator yet, but I've checked my battery voltage and it always checks out (I know its not the same). I'll get it checked.

With regards to the map sensor, I was using a MAP sensor for boost logging purposes only, not for tuning, so it wouldn't affect anything.