LS2 Max'd Out?

[TheDastardlyDuo]

Forgive me, the title should be "LS2 MAF Max'd Out"

First I'd like to thank Chris for helping out with the speedo problem on the 2005 C6. Since I have the car back, I decided to get some more HP pulls on the dyno, The AFR is very nice between 12.0-12.1 the whole way to about 6200rpm, then it starts leaning out finally arriving at 12.9 at 6900rpm. I'm thinking the MAF is being Max'd out (having seen this happen a lot in S/C Fords), the scan shows the Hz exceeding 12200hz (limit of the High frequency MAF table) at about the same rpm as it starting to lean out. Hz at the 6900 rpm is 12800hz or so. Enclosed are the Scan File and Tune. I tried adding fuel above 6250 through the PE table, but it had no affect. Any help would be appreciated.

Mike

[Bill@HPTuners]

your commanded a/f ratio is 13.4:1 all the way across on a boosted motor...thats probably a good part of your problem...are you sure you even attempted to change the pe table? if so it looks like you might be going the wrong way

[TheDastardlyDuo]

PE table is adjusted per Wideband readings, using a LM-1 and Mustang MD1100 Dyno. I understand that 1.099 PE should be 13.4, but when the PE table was 1.225 (Command 12.0) the actuall AFR using the same LM-1 and Dyno was 10.68. Wideband pick up was placed in collector of driver side header.

Mike

[Bill@HPTuners]

2 seconds ago you said "I tried adding fuel above 6250 through the PE table, but it had no affect."

now your saying "when the PE table was 1.225 (Command 12.0) the actuall AFR using the same LM-1 and Dyno was 10.68"

which one is it?

[Russ K]

The LS2's should have a MAF patch to allow up to 15000 hz. Look in the OS options.

Russ Kemp

[Bill@HPTuners]

yeah he has the patch applied from what i saw in his file.

[Pomp]

The ideal AFR is around 13.0 so you still got some to lean it out. With my 386LS6 is 13-13.1 across the board. You will pick up some horses as well as fuel economy.

[redhardsupra]

is this FI or NA? you max out the MAP at 3000rpm, so i'm gonna guess FI

[TheDastardlyDuo]

Car is force inducted (procharger S/C, 60lb/hr injectors, custom ground cam, full exhaust minus cats, 3000rpm TC, 3.90:1 gear, and a boost-a-pump), with the file I uploaded into this thread (PE=1.099) AFR was 12.0-12.1 until 6200rpm then gradually rose to 12.9. In a previous tune (PE=1.225) AFR was 10.68. The 15000Hz patch is applied, but that's just for MAF fail Frequency (or am I wrong?), the largest value for Hz in the MAF High Freq Table is 12200Hz. I am now uploading the tune file that had took into account more fuel above 6250rpm, but the result on the dyno was the same. However I do not have a saved log of that run.

Mike

[Bill@HPTuners]

the pe table is in rpms though...if you keep it flat & not EVERY other table is spot on perfect you can easily go rich OR lean...the perfect pe table is rarely a flat line all the way across.

[TheDastardlyDuo]

I'll have the dyno sheets scanned to post them. But can anybody help me with MAF values greather than 12200Hz's?

[SMOKINV8]

Once the MAF is maxxed out, the PCM uses the fueling value for the last cell in the MAF table until the values come back within its range. You can band-aid this by adding fuel via the PE table in the RPM range where the MAF is maxxed and more fuel is required.

[redhardsupra]

just read this from yesterday:
http://www.ls1tech.com/forums/showthread.php?t=571490

[TheDastardlyDuo]

Here's a Pic of the Dyno Pull (sorry about the blurriness, damn camera phone), the black line is the AFR. That pull was with PE=1.099 across the board (FinalCorrect1 File). When more fuel was added via PE (FinalCorrect1PE2T18 File), the AFR was identical. Car has a fuel pressure guage, and the needle is static at 60psi through the hole pull.

Mike

[SMOKINV8]

RHS has a very good point though, did you upgrade the fuel system to keep up with the fueling needs?

[TheDastardlyDuo]

Car has an inline booster fuel pump and a Kenny Bell Boost-A-Pump voltage step up. I'll try and get a better pic of the dyno sheet up on monday.

Mike