Dan Brown

Hello All-

Tuning my car, already got the VE table pretty close. I'm getting stuck with EQ ratio though, as my car is going very lean during WOT. I have re-calibrated my LC1 a few times just to make sure I wasn't crazy.

To try to get 12.8 AFR, I'm having to dial in 1.4, or as high was 1.55 in some places. Commanded on the log shows 10.0 or so sometimes to get me an AFR of about 12.2-12.8. Commanded during cruise is 14.62 and my wideband AFR is very close, only giving me 2-3% error.

Any ideas on what I should check? I'm wondering if my fuel pump is on it's way out and isn't getting me the rail pressure I need above idle values during WOT. VE was pretty easily tuned around Stoich, it's just getting WOT to fall in that's giving me fits.

Thanks!

jimmyblue

iTrader: (11)

That says you either have a bad airflow error in the
MAP dimension of the VE table, a whack MAF calibration
(the MAF itself being fouled or spoofed, or the tune just
wrong), or a fuel delivery problem at higher demand.

I think the motor combo is pretty common looking,
the easy bit might be to compare your VE to someone's
repository tune that looks like they knew what they
were doing. Which can be a crap shoot in itself. If
your VE table looks comparatively sane then fault out
the MAF and see if the accuracy commanded vs LC-1
comes around. Yes = fix the MAF.

Cleaning it wouldn't be a bad idea too, especially if
you're using an oiled filter. Junking it wouldn't be
a bad idea if it was "ported".

If the MAF and Dynamic airflow agree pretty well
and your VE table is sane-appearing then you are
left with the fuel side. Perhaps a cheapo Actron
gauge, a couple of barb fittings and some extra
fuel line could get it up to the windshield where you
can read it all the way to redline under load.

Misfiring can spoof your wideband sensor with unused
air. That's another possibility.

Dan Brown

Jimmy-

Thanks for the reply. Let me give a little more detail:

-LS1 w/LS6 intake, 224/224 560ish/560ish/112 cam, LT, High Flow Cats, Flowmaster Muffler
-For tuning car has been in OLSD, COT off, DFCO off, MAF unplugged
-My Tune is about 10% fatter (higher VE) then two similar tunes I found on HPT's website in the mid range and also WOT cells. Both those tunes were OLSD so I would expect them to look similar during OLSD tuning (?)
-I plan on running my MAF again once I get VE/PE tuned, but again it's unplugged for tuning.
-Spark tables are identical
-Primary and Secondary VE are identical (I make corrections to Primary, then copy the 10's row cells over into the secondary)

Attached is a copy of the current file I'm using with a 25-min road session. Most of the WOT runs are in the beginning. Hopefully someone will see some stupid error that will be an easy fix! Thanks again!

ND2RACE

IMO comparing tunes is a waste of time, there are just too many variables. It doesn't really sound like a fueling issue if you can command richer and get to where you need to be. It just sounds like you need to continue to work on the VE table in the WOT area, since you stated that you're still working on OLSD with the MAF plugged in. Set it up to command 12.8 and use the correction factor in that part of the table.

Dan Brown

This is the only reason I think I might have a fueling issue. Let me take an example from my log:

At ~4000 RPM my Commanded AFR is approx 9.5
My observed AFR is 13.2 at that point.
My 100 kPA VE cell is 90 in both Pri/Sec VE tables

So, in order to fix this problem, I go and Command 12.8. However, wouldn't that bring my VE for that cell well over 100? If that cell value was 60 or 70 I might feel comfortable making a large correction and getting up to 90-95ish. But unfortunately I'm already there and would have to go over 100.

Maybe I'm straying to far here, but I don't think the LC1 is crazy inaccurate. I'll go recheck voltage offset, but when I actually get the AFR close to 12.8, the car is picking up a good amount of power.

Slow 346

iTrader: (33)

In my cam only car, most of my values in the 95 to 105 kpa range are in the 111 to 115 range from 4800 to 7200 rpm. My AFR is a little rich at 12.0 to 12.4 so im gonna work on that next and lean it out.

jimmyblue

iTrader: (11)

If you have very high VE values it probably means you
are correcting some non-airflow errors with the airflow
model. Over-unity VE is -possible- when resonant effects
are in play and the rest of the pipe is not costing you,
but it's pretty unlikely to be that way for real, over a
wide RPM range.

Slow 346

iTrader: (33)

Whats considered a high VE value? Im running OLSD btw.

Dan Brown

Well guess what I found. A Fuel Rail pressure of 45psi. Jumped into the tank and found a split feed line from the walbro pump to the top of the housing. Replaced that bad boy and have been watching my scan's read highly negative all afternoon.

Thanks for the responses. I haven't gotten VE totally dialed in so I haven't moved to checking WOT. Hopefully when I had the 45psi rail pressure, I didn't go lean enough to hurt my motor.

AutomagicLS1

iTrader: (18)

115-120+