PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Tuning problems with LS1edit

Thread Tools
 
Search this Thread
 
Old Feb 9, 2003 | 05:21 PM
  #1  
Blkdoutbird's Avatar
Thread Starter
Staging Lane
iTrader: (5)
 
Joined: Aug 2002
Posts: 83
Likes: 0
From: Fresno,CA
Default Tuning problems with LS1edit

I have posted his here before but I didn't get an answer so I'll try again. I have a 02 WS6 with a lid,MAFends,smooth bellow, and a cutout, and I recently edited my car. What I did was raise the timing 8 degrees from 800rpm-2800rpm, and 4 degrees from 3200-6400, raised the rev limiter to 6500, and took out the torque management.The problem I am having is when I powershift the car the fuel drops way to to around 200mv when it is normally around 890-910.When I lift off of the gas to shift it doesn't do this though, and I definitely did not do this when it was not edited.So is there a table that I have missed that controls the fuel at WOT? Where are your guys' rev limiters at and how many of u powershift and don't have this problem? If u know what it is that is causing this problem or an idea please help me!!!
Reply
Old Feb 10, 2003 | 11:19 AM
  #2  
Doc99SSx's Avatar
Teching In
 
Joined: Aug 2002
Posts: 44
Likes: 0
From: Dearborn, Michigan
Default Re: Tuning problems with LS1edit

First of all, your terminology is confusing, such as, "fuel drops". When I first read your post, I thought that you were talking about fuel pressure.

When you say "fuel drops", I think that you mean "during a power shift at WOT, the AFR gets leaner".

AFR is air fuel ratio, if you didnt know.

This timing change, is this the first thing you changed after getting LS1Edit????

You have a modified (ported) MAF sensor. The MAF table in the PCM does not represent the flow of your modified MAF. The first thing you should do (IMO), is to re-calibrate the MAF table to correlate the the actual flow/frequency of your MAF sensor. You do this by logging the LTFTs over many fuel cells (same as engine load cases). You do this at part throotle.

IMO, you need to step back, and think about what you are doing with LS1Edit. What do you want to achieve??? I'm not trying to be a smart ***, its just seems like you jumped into this tuning stuff without a game plan and technical approach to what you are doing.
Reply
Old Feb 10, 2003 | 07:25 PM
  #3  
Doc99SShome's Avatar
Staging Lane
 
Joined: Feb 2002
Posts: 97
Likes: 0
From: Newport, Michigan
Default Re: Tuning problems with LS1edit

First: put back the stock timing.

Second: go out and take some ATAP logging sessions, record LTFT (both banks), fuel cell, engine rpm, MAF frequency, and MAF flow (in gms/second). Log files at part throotle, trying to visit many load cases,, this is your fuel cells. Each fuel cell will have its own LTFT (Long Term Fuel Trim). While you are out getting part throotle recording, get one or two at WOT and add in the O2 output & KR & total timing.

Come back home and bring up Excel and read the ATAP log files one at a time. Read in the log files as data files separated by a comma. You should end up with all of your data in nice columns. Save these files with a unique name that you can refer back to days from now. Now study these files. What is the LTFT value at idle (fuel cell 19)???? What are the LTFT value at low engine load (fuel cells 4 and 5)???? What is the LTFT value at mid-range (fuel cells 9 and 10)??? What are the LTFTs at upper end just before the PCM goes into WOT (I think this would be the 14 and 15 fuel cells.)

High positive LTFTs (above +10%) means that the MAF table should be re-calibrated because you modified the MAF sensor. If the LTFTs are slightly positive (0% to +5%), you can change the fuel injector table downward. The objective is to end up with negative LTFTs, between 0% and -5%. The main reason for this objective is that at WOT, the PCM will dump in more fuel equal to the LTFT value IF the LTFT value is positive. If the LTFT values are negative, no fuel is added or taken away during WOT due to the LTFT value. With MAF ends and no screen, you might be running around with the LTFTs up at +15% to +20%. This is not uncommon.

So first tune the part throotle stuff, then tune the WOT fueling for 12.8:1 AFR, then work on the timing table for best performance at WOT, see if you can get 28* at WOT. There are several other things that you can do, and maybe you have done some, like raise the RPM limiter (if you have an M6), lower the fan temps, etc. If you have an auto, there are some things to be done there to, but I cant advise you on this.

Modifying (re-calibrating) the MAF table is not a simple matter. It is not a simple across the table multiplication. Let the value of the LTFT guide you in how much to change each portion of the MAF table by frequency. The bottom end of the MAF table, the engine is at idle or just off idle.
Match up the fuel cell number, MAF frequency and the LTFT in order to dicide how much to change the flow values in the MAF table. Also, very important, you must end up with a smooth looking curve for the MAF table. Look at the stock MAF flow table in graphics form before you change it.

Also, its a good idea to file away the stock PCM program so that you can go back to any specific stock table if you get out of control with your editting stuff.

OK, I'm tired now!!!!
Reply
Old Feb 11, 2003 | 06:36 PM
  #4  
Blkdoutbird's Avatar
Thread Starter
Staging Lane
iTrader: (5)
 
Joined: Aug 2002
Posts: 83
Likes: 0
From: Fresno,CA
Default Re: Tuning problems with LS1edit

Thanx for all your help, by far u are the most helpful and informative person on any of the boards I am a memeber of, thank u again!!!!
Reply




All times are GMT -5. The time now is 06:47 PM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE