Bluestreak

I'm sure you guys are tired of reading this topic in its various forms... but I need your help in finalizing the decision to use LS1-Edit on my car. Here's some history...

I never really worked on cars until I got my '99 Trans Am. I never even thought about anything more than routine maintenance, which was always performed regularly on my other cars. Then I got onto message boards like these and started to get brave. Using an install documents and a set of shop manuals from Helm, I put a cam in my car. This past weekend myself and 99RagtopSS successfully completed a heads/cam/header install on his '99 SS. Except for the fact that the Ed Wright program wasn't agreeing with the car and its new modifications.

Seeing Jeff's car **** all over itself from Ed's programming was the final straw in my decision to go with LS1-Edit for my application. No matter what anyone has said thus far, I can't abide by letting someone 1,000 miles away program my car, sight unseen, then lock me out of my car's computer - especially when that program might not be right. Playing the "back and forth" game with <*insert favorite tuner name here*> will cost me at least 48 hours and the cost of overnight shipping every time I have to send the PCM out to be reflashed. Add that up... and LS1-Edit seems much more economical, too. $400-$500 for a single tune, plus shipping... that's probably within $50-$100 of the cost of LS1-Edit, for the ability to flash my PCM as many times as I want, whenever I want.

Now, I'm also very computer savvy. I know how to program in ASP/VB/SQL and C/C++. Which means there's no problem with my computer skills. However, diving into the car's computer using LS1-Edit would be totally new territory for me.

Soooo... say I buy LS1-Edit and I hook my laptop up to the car. At this point, my car has its 100% stock original program in the PCM. Now, backing up the original program would likely be the first step, as you would with any other computer with which you're going to tinker.

My first modification as an LS1-Edit user would be to delete the EGR so I can install my LS6 intake... which has been staring at me from across the garage on a shelf since I got it on special price from PaceParts.com 6 months ago. Then, based on the other mods in my signature... where would I start? What would I want to edit to enhance the performance of my car based on the installed mods? Is there sufficient documentation with LS1-Edit to provide me with a good starting point, or would I need to rely on the experience of others (most likely this forum) to help me learn how to use the software? Resolving these issues will be all I need to convince me to get started with LS1-Edit.

From what I have learned working on F-bodies, 99% of working on a car is simply having the confidence to try and the patience to learn. I have that. Case in point, a year ago I'd change the oil... but that's it. Today, I'd change a clutch... cam, heads, exhaust, you name it, I can do it. All I need is for someone to give me a good starting point, some pointers, what to beware of, and I'll be fine.

Please help me get started, thanks for bearing with me, and sorry this got so damned long. Thanks.

Godspeed

It's entirely up to you about what you want to do for your tuning. You can use it to correect problems such as idle, cold starting, part throttle performance, or WOT performance. In order to accomplish this at a minimum you are going to need to use some kind of data acquisition software such as Autotap. You can use this software to look at what the car is doing - things such as RPM, ignition, fuel trims, O2's, etc. Based on the information from you diagnostics you can use LS1 Edit to make changes to your PCM. Things like adding more ignition advance or pulling out some fuel. Ideally the best way to perform this process is on a dynojet with widebands to monitor the AFR's and with a Tech 2 to get a snapshot of what the car is doing. Once you do a fuel pools on the dyno you will be able to see how smooth your curve is, what the AFR's are, and determine where you need to make adjustments. <img src="graemlins/gr_cheers.gif" border="0" alt="[cheers]" />

-Jeremy

NicD

iTrader: (7)

Doc99SS, I have read that its best to correct the LTFTs with injector flow rates rather than MAF table changes. With my cammed car, my LTFTs were around 20+! I scaled my fuel injector flow rates by multiplying the table by 92% (to basically make it richer) to correct my LTFTs. Now they are around +5 to +10 on avg (from which I understand +10 is best for timing advance, etc). From then on I am going to do some dyno pulls and O2 readings from Autotap to help determine what I should do with my PE tables. Also going to look into desensitizing the knock sensor, or making it have less effect on the timing curve. Any ideas on that one?

Doc99SS

iTrader: (2)

Black LS1, Thanks for the comment. I'm making about 400RWHP now, your 487RWTQ must feel GREATTTT.

Nic00Z28M6,
Well, you make a good point concerning the timing.
Before my PCM changes, I was pulling 27.5 degrees of timing at WOT. Now that I have Lterm fuel at 0% to -5%, I'm getting only 23 to 25 degrees of timing. But, I can alter the timing table. OR I can go back into the MAF table and decrease the values by 5% across the board. This might bring back my Lterm fuel to a low +% values and give me more timing.

There are several ways to do stuff. I'm still testing things out as I go.

NicD

iTrader: (7)

Anybody got any ideas on the knock sensor part from my post above?

Doc99SS

iTrader: (2)

Well, there is a table concerning knock attach rate. I multiplied all my values thru by 75%.

I believe that this will make the knock sensor less sensitive. I believe that I am getting some false knock. I have not tested this out yet due to snow.

Doc99SS

iTrader: (2)

First of all you do NOT do any actual programming with LS1Edit. Your c++ programming skil is useless. Sorry but true. I hope this doesn't sound to harsh, hey I've been doing Fortran programming for about 30 years plus. I dont use it to edit my '87 Eproms or my '99 PCM.

What you do with LS1Edit is modify the contains of various tables. These are look-up tables that the PCM uses to determine the instantaneous best Fuel/air ratio and therefore, the fuel injector pulse width.

For example, I did a stage 2 head/218 cam install with GMS MAF, ported TB, LS6 intake, headers, etc.
This engine does not perform much like the factory unit anymore. With the aid of AutoTap, I am running very lean on cruising around and very rich at WOT.

My Lterm fuel trims were 15% to 20% (the PCM was adding more fuel in by that percentage). When I went into PE mode (WOT), this extra fuel was added in along with the extra fuel from the PE tables. That is why I was running so rich at WOT.

The first table I have been modifying was the MAF table. The actual amount of air that the engine was getting thru the GMAF did not match the MAF table in the PCM. When I got that under control(with Lfuel trims at -5% to 0%), I modified the PE table (the one vs RPM). I was running 970mV to 990mV on the O2 sensors at WOT. Now with the aid of LS1Edit, I am running about 880mV.

After some work on the timing advance tables, I will get the car back on the chassis dyno and see if I have done any good.

Black LS1 T/A

Doc99SS, great reply!

Also, if you are making over 350 RWTQ, th stock tuning will pull timing out to reduce the torque, to <img src="graemlins/gr_guns.gif" border="0" alt="[guns]" /> protect the tanny from so much power.

Well, my Max Torque figure is bumped to nearly twice that so my car doesn't nose-dive at each shift (I'm currently putting down 487 RWTQ).

There are MANY things you can modify for performance.

Also, my peak horsepower is now at around 486 @ 6400 RPMs (actually it may be more... that's when I told him to stop acceleration on the dyno. <img src="gr_grin.gif" border="0"> )

With the stock shift points I would not even be close to my peak HP during shifts.

Much you can do!
<img src="graemlins/gr_cheers.gif" border="0" alt="[cheers]" />

ToplessTexan

[quote]Originally posted by Nic00Z28M6:
<strong>Doc99SS, I have read that its best to correct the LTFTs with injector flow rates rather than MAF table changes?</strong><hr></blockquote>

Well, the MAF table is really the best place to calibrate the MAF. (Remember that GMAF he had?) That will do a lot to bring the trims back in line. The remainder could well be handled with the flow rates.