muncie21

iTrader: (14)

I've got my VE pretty much mapped out, but I'm noticing a lean surge right at 2000 RPMs in 1/2/3 gear under light load (35-40kPa or 24-27 g/sec). WB shows 21 AFR at this point. BTW, this is CLSD. So far I've been pushing the VE up in these cells, but I don't think this is the right way to approach it.
Oh, and I moved the RPM limits for the FTCs so FTC 6 covers 1401-2500.
Any ideas?

muncie21

iTrader: (14)

Did some more sleuthing, the lean surge happens in open and closed loop, with the MAF on or tuned out.

Is there anything mechanical that occurs around 2K RPM, engine wise?

GuitsBoy

iTrader: (4)

Nothing mechanical that I know of, but I have the same bucking at 1600-1800. Low rpm, low load bucking. Seems to be par for the course. Sometimes it will buck sometimes it wont. I cant figure out the rhyme or reason to it, so I cant figure out how to tune it out. So far my open loop MAF tune has lessened the bucking as much as possible, but its still there a bit. I dont know why youre seeing 21 a/f are you sure youre not going into DFCO? Thats the only time I go that lean.

muncie21

iTrader: (14)

Here's a shot of the surge. This one topped out at 18.xx, but some are higher/lower. Don't pay attention to the O2s, as it does this in open loop also.

Joel_SS

iTrader: (8)

Did you ever figure this out? I am getting the same problem right around 2k. I am pretty sure I have an intake leak though..

muncie21

iTrader: (14)

Nope, I still have it.

If you look at the pic of my O2s (a few posts up), it's only on the passenger side. I've changed the intake gaskets and still have it. Not sure what else would let air in to one side of the engine only. Guess I'll look at injector O-rings next.
I've seen another vette with the same issue, so I'm wondering if there's anything mechanical or otherwise that would cause this.

SSpdDmon

iTrader: (10)

Are you by any chance dealing with a lazy O2 or using the LC1 to simulate a NBO2? You're getting some huge swings in your trims and/or some lazy activity from Bank 2. Bank 1 looks somewhat normal...

muncie21

iTrader: (14)

I'm simulating the Bank 2 O2 with an LC-1. I can actually feel the car hesitate right were the surge happens if I am driving slowly. I'm about 98% sure it's real because when I force open loop (doesn't rely on O2 feeback) I still get the surge and can also feel it hesitate.

badpewter-z

iTrader: (4)

just went threw all this crap myself and it was an intake leak

SSpdDmon

iTrader: (10)

Just to be 100% sure, I'd replace the LC1 with the stock sensor and see if it still does it.