Lean @ WOT after LT's
 

My buddy installed LT's on his 00 A4 T/A and ditched the cats, AIR, & EGR. But a performance gain has not materialized; he's trapping the same or less than my manifolds car. We logged AFR with an LM-1 and it hovered pretty close to stoich at part-throttle. But WOT through 2nd & 3rd gear came up at a steady 13.8/13.9. Previous LTFT logging showed a range of -9.4 to +9.4. His PE at rpm modifier is stock at 0.8 across the board. We're tuning noobs and wondering what the next step is to try to address this. Thanks for any help.

Did you scan for knock retard? Thats the first step. Its very possible to get false knock with aftermarket exhaust. If it is really false you can desensitize the knock sensors to fix it. And it could also be real knock from being lean.

Second, those fuel trims are all over the place, going from -9 to +9 is a big difference and will cause inconsistent AFR's at WOT. This car sounds like it needs a tune. Unplug MAF and log a drive then tune the VE table to get LTFT's locked at around -2, then plug MAf in and log again then tune MAF table to get trims at -2. Then change PE table to reflect the AFR you wish to acheive. Right now with PE at .8 you are commanding 18.3. If you want lets say 13.0 AFR at WOT you want the PE table to be at 1.131 (14.7/13.0=1.131)

Who put his PE table at .8 anyway??

Yes, we scanned and there was some KR ... I don't have the log in front of me but it was for a brief range in third gear as I recall. I had nearly the same on my car, though, also. I don't think it's anything in the exhaust banging - it's a good clean install; I drove it today and didn't hear anything. We do only get 91 octane around here.

That's why I brought up the LTFT's - there was some variation in AFR in part-throttle driving, but it was VERY steady at WOT - how does that make sense?

0.8 is the stock PE multiplier - check it on a stock 00 table. 14.63 x .8 = 11.70 - which is the commanded WOT AFR according to the EFILive scan. Hence:

PRI CAPTION DESCRIPTION VALUE UNITS MIN AVG MAX
1 AFR Commanded Air Fuel Ratio 14.63:1 11.70 13.71 14.63

You are off on the WOT AFR calculation. I dont know if EFI changes it for you or what, but I use LS1 Edit and if it is a fuel multiplier table then at WOT you want it to be more than 1, if it is less than 1 then it will command less than what is set in the MAF table.

If stoich is 14.7 and the closed loop tune is dialed in, you take the stoich AFR and multiply that fuel amount by the amount of extra fuel you need to acheive a desired AFR at WOT. So since you need mkore fuel at WOT your fuel multiplier will be more than 1, not less.

yeah my stock 00 table commanded 11. something and my fuel multiplier table was at like 1.3 or something like that.

1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328 1.1328

Thats my PE table values, I actually get what i command too. 13.0 all across

Yeah, I bet EFILive uses a different calculation - the stock 00 Camaro tune they include shows .8 in all cells, as do both my car's and my friend's. Problem is, he isn't getting what's commanded - my first instinct was /simply to adjust the PE table to correct that.

No dont just change the PE table. Change the PE table to command what you want, then tune VE and MAF to get accurate airflow measurements and then your WOT AFR will be close to what you are commanding.

So do headers typically require a VE/MAF tune? This seems to be what is indicated, but we're a little apprehensive about getting in over our heads. EFILive does offer an AutoVE tuning procedure that, while complex, does seem doable. Seems like a bit much, though, for a lid, catback, headers scenario.

Not typical but it happens. I ran lean with headers and a few other boltons too on a stock 2000 tune.

Thanks for the advice - it's appreciated! Unless someone else has some fresh revelations for us, it looks like we have some serious study and work to do.

If you are only concerned with AFRs at WOT, then the quick and dirty method is to increase your PE value until you hit your targeted WOT AFR value.

With this in mind, you must realize that your VE and MAF are probably off a little. If it's only off a little your fuel trims should compensate.

I normally don't advocate the short-cuts, but here is seems you have limited tuning knowledge and only one goal in mind...being AFR during WOT.

Just an idea, but check for a vaccum leak since you pulled out the emmissions stuff.

I had a small one & it sent my A/F super lean & my fuel trim was +25. I had no idea until I got my edits done & my tuner showed me what was goin on. Its fixed now & my lost power is back & my gas milage increased a good amount.

I'm a total noob at tuning stuff, but its a idea.

I replied to your post in the EFI Forum. What you're talking about is a difference in units. Lambda, EQ, and AFR are all possible units you can see in your tune. It's up to you and your preference. Don't take the advice of just increasing or decreasing your PE table - not until you find out which units your looking at (top left box in the PE table window). Increasing lambda leans out AFR, increasing EQ richens AFR, and the opposite is true for both. Just to make things easy, switch your display to AFR (Edit>Properties). Then, there's no confusion.

Thanks again - all of this is clear; as to what to do about it - that's the question. I'll double check for a vacuum leak. There is a line for the AIR that was plugged and maybe it's become unplugged. We're also going to clean the MAF - he had been running a K&N. If after those, he's still lean, then it's on to whatever the best tuning protocol turns out to be.

If it was me, I would do a quick tune on the VE table and then proceed on to the MAF. With a car like that and the mods, it shouldn't take you very long to get it dialed in. If you want to upgrade it to a later OS, then you may or you can use the existing 00 if you like, it is up to you as the concepts are identical for both. I would personally change it to a 02 and be done with it.

I need a 02 OS, I hate having 2 VE tables.

Since it's an '00 it has the stumpy little injectors.
Be sure to keep an eye on injector duty cycle, get
a look at fuel pressure (especially if it's got the
original fuel filter) at WOT too. But this all shouldn't
affect it across the band, only at the top end or on
a trend to the worse with RPM, not flat error profile.

People like to dislike the MAF but if it's not messed
up by modification or contamination it's one of the
more reliable sensors on the car, immune (first order)
to post-MAF airflow / VE changes. If you see OK
trims in Cell 1, Cell 5, Cell 9, Cell 13 then the MAF
is probably not so bad. If you see big differences
0/1, 4/5, 8/9, 12/13 that is telling you MAF and
SD tunes are out of bed.

You might want to rejustify the fuel trim cells to
use them all, fine-grain the low end, etc.

Was the wideband in the tailpipe or in an I-pipe
bung? Tailpipe mounts can be untrustworthy
and if wrong, err to the lean (fresh air reversion).

when you guys ditched your egr/air did you ditch the whole system or leave some hoses hanging there?

i lost 1/2-1 mph trap after an lt and ory install.

I left a bunch of shit in there for a while, then I got rid of it all.