LTFT tune puts a VE cell at 0?

[chrisfair]

Obviously something is wrong but I'm having trouble figuring out what.

Installed new PRC LS6 and TR224, also LS6 intake, Pacesetters LT's with TSP off road Y, SLP UD, new TR55's, wires, and Racetronix 42lbs (plenty of breathing room). I calculated the new flow rate rate for my injectors and the car started on the first shot.

It kind of runs like ass, backfires every now and then. It lugs and when I hit the throttle it has a steady hesitation at part throttle and falls on it's face at full. It was running pig rich but while I've been waiting for my LC1 (just got it yesterday, haven't had time to install) I've been tuning my car using LTFT's and STFT's to get me in the ballpark and it's helped some.

The problem is that I keep logging negative LTFT's that have sunk some VE cells to 0. This can't be right. It's only occuring in some cells in the lower rpm and lower MAP regions of the LTFT map in EFILive, where the computer looks when coasting, off throttle. I'm sure that something is up that is affecting the entire range though, that would explain the drivability problems.

I have replaced my bank 1 O2 with a Bosch 13111 and the LC1 is going in bank 2 this weekend.

What could be making my LTFT's keep trying to dive down like this? Leaky header or vacuum leak? Lazy O2? I would expect to see it trying to fuel a vacuum leak, not cut fuel. Could I have a bad injector dumping fuel? All the header tubes seem to be about the same temperature, I ran for a little bit and felt each tube, and then later sprayed a little water on each after driving around for a bit. The water boiled off about the same for each so it seems like all 8 cylinders are lighting off ok but who knows.

I have included my current tune showing the 0 VE cells and a log I took on my way in to work. If anyone has time to take a look at these I would appreciate it.

http://www.unf.edu/~n00193816/tune_and_log.zip

Oh, and I am remembering to update the secondary VE when I'm updating the primary, so that's not the problem.

I have also posted on the LS1Tech forum.

[dc_justin]

It does appear that you have a vaccum or exhaust leak causing the differences in trim values per bank. Check out frame 7920. bank one is flatlined, Bank 2 keeps reading leaner and leaner. Get that fixed first and foremost.

For the falling on it's face at heavy throttle... you have PE mode disabled with your PE modifier = 1.0 at all RPM ranges, you should not be driving it hard like that. Not safe at all. A melted piston on a new motor would not leave you a happy camper.

My suggestion would be for you to fix the leak, then return the tune to stock and follow the AutoVE tutorial. You'll have your VE table(s) nailed down within a couple of hours.

[chrisfair]

Yeah your're right, but I wasn't doing any full throttle to the redline stuff, just giving it a more gas to watch the MAP go up. It idles in gear at 50, 55, 60in the MAP range. So it doesn't take much throttle to put it up to 100 or so, Maybe that is part of the problem?

So intake or header leak? That's not too bad.

[chrisfair]

Ok got the LC1 in and have been tuning for a week now but I'm still having the same problem.

In the 1200 to 2400 rpm, 20 to 35 kPa range (off and very light throttle), I keep getting BEN factors that are taking my VE's to 0 in those cells.

Here's a log and tune to illustrate what I'm talking about. It includes injector pulse width and duty cycle info. I'm concerned it may have something to do with my injector tuning. I've got 42# from Racetronix. I changed my injector flow rate table to match the new injectors and checked my pressure at idle (58 psi).

Plugs are good, can't find any vacuum or exhaust leaks.

http://www.unf.edu/~n00193816/SDAutoVE.zip

[SSpdDmon]

Are you making changes to the primary VE or secondary VE?

Are you sure your MAF is disabled?

If you had an exhaust leak, the failing side should be reading lean on the O2 and have high, positive LTFT's. Just a word of warning...becareful with the Bosch sensors. I've seen them screw up in both of my friend's cars right out of the box. The unreplaced side will look like normal and the other with the Bosch will be jumpping all over the place. You can get ACDelco's at www.rockauto.com (http://www.rockauto.com) for A LOT less than the dealer will charge you. Just my $0.02.

[chrisfair]

Yup, changing secondary VE's, MAF is disabled and O2's shouldn't matter right now because I have trims disabled and am using a wideband for tuning.

I keep searching but I haven't been able to find the answer.