: LT1 PCM tuning



N0DIH
01-16-06, 11:43 PM
I talked with Jesse Bubb who runs Wait4Me Performance and he does do LT1's (not too many, he specializes in LS1's and diesels and Vortec's). He is well known in the truck world and just did my PCM for me on my 96 Burban.

He knows the tuning well and will do what you want or need and his prices are very fair.

$75 for tune and lifetime retunes (limited time only! Check website for more info)
$150 for tune on another PCM mailed to you.

OR, as I did, I stopped and had him do a few more goodies to my PCM that isn't in the normal run. Anything (almost, don't ask on lean cruise....) can be done if it is in there.

www.wait4formeperformance.com

My Suburban is much more responsive and drivable now. Now drivability is on par with my LT1! I always said there is something wrong when my 4400# LT1 @ 260hp w/3.42's is a world different than my 255 hp Vortec w/3.73's (taller tires, overall effective the same) and 4600#. Now they are very close to each other in throttle response and drivability.

I will send mine back to do some PCM work on the trans shifting, as I want it more like my V4P Cad. But now I feel that I could tow easily. The guys at fullsizechevy.com seem very happy with his work.

caddycruiser
01-16-06, 11:46 PM
This has always seemed interesting to me, but I don't think I'd ever know what exactly I wanted to be changed...:cookoo:

N0DIH
01-17-06, 12:01 AM
He said on one of the OLD PCM's, there is 980 tables of data that can be changed.

It isn't trivial what to change and not to change. There is countless hours he has spent learning. We talked for some time while I was there and he knows a lot. Lots more than anyone else I have talked to. He knows the routines and strategies GM uses to do things.

On mine some of what he changed:
WOT fuel mix from 11.2:1 to 12.2:1
Speed limiter removed (was 98 mph, not that I ever go that fast in the truck)
Redline from 5500 to 6000 rpm (honestly, with that cam, 5500 to 5700 is plenty)
Tire size fixed from 245 75 16's to my current 265 75 16's.
Min speed trans engage to OD 38 mph (was 27.1 mph!!!)
Increased cruise rpm resolution for fuel mix metering (best way to describe it, very hard to explain without showing you, and I don't have the program to do it, yet....)
Firmer trans shifting
Enabled it to USE higher octane fuel and learn from it to up the timing maps (this particular PCM can do this), this is disabled by GM in the code, not a simple on/off bit, but a whole slew of changed to make it start to adapt to the higher octane.
Disabled rear O2 SES light if a failure occurred or O2's removed.

And about 200+ more data points that he whizzed through so fast I didn't catch them all.

Jesse has tons of hours with these engines on the chassis dyno, he really DOES know what works and what doesn't. He has many customizations that are unqiue to him (the resolution area, many of them he puts in, just amazing what he has figured out on the GM PCM!).

It isn't simply timing and fuel changes, it is much much more. I wish I could have kept on it what all he did! It would take someone weeks to reverse engineer what he did.

So many tables were either railed (maxed to 255 or 0) or set flat where they didn't do much. Seems GM designed in a lot, but didn't use it.

caddycruiser
01-17-06, 12:23 AM
Wow, sounds awesome. I could definately see doing something like this, if I ever decided snappier performance down low or firmer shifting would be nice.

Actually, that'd be good on the '93...wonder how much it could be changed:cookoo:

N0DIH
01-17-06, 12:34 AM
Give him a call (his number is on his site) and talk to him. He works almost 100% out of his home now. Just too much work!!

The 93 probably can't do shifting, only on the 4L60E and 4L80E (and 4T60E, not sure if he has files on the N*) But he can change TCC lockup points.

We talked about the abuse modes and cat converter protection modes and how it goes into them. About how the PCM determines a lot of things. Seems GM has advanced much of the long/short term fuel trims and how it handles those. Cool stuff!

Katshot
01-17-06, 06:57 AM
There IS a lot of things possible with these PCMs. I've enjoyed "playing" with mine via LT1-Edit. Personally, I set my min. TCC engage at 50mph though.

caddycruiser
01-17-06, 12:51 PM
There IS a lot of things possible with these PCMs. I've enjoyed "playing" with mine via LT1-Edit. Personally, I set my min. TCC engage at 50mph though.

I'm having a dumb moment...but what does TCC stand for?

On second thought, the '93 is fine, but someday I might feel like changing up the shifting of my new '95...maybe. Still haven't driven it enough to know much of anything:bigroll:

BCs71
01-17-06, 01:09 PM
The 93 and earlier Fleetwood use the PROM style of programming which basically necessitates the burning of PROM chips that must be changed out, to the best of my knowledge.

The 94-6 Fleetwood uses a PCM, which is read/write-able via the ALDL connector under the dash. Hook up your laptop, save the old PCM data, and then download the new program data to the pCM and in ten muntes or less -- voila! Easy as pie.
I'm currently using the mail-order programming (program was emailed to me and I used a laptop to download program myself) from Bryan Herter at pcmforless.com which was $50 initial tune for OBD1 (1994-5) or $75 for lifetime programming. Unfortunately he just changed his policies on lifetime tuning so that isn't offered anymore for new customers....

I have earlier cooling fan turn on temps (GM programmed these at high temps for better emissions but at the expense of power).
Firm tranny shifts by boosting line pressure (very cool to have)
Fuel trim changes (necessary for my aftermarket cam but even on a stock car the car is pig rich at wide open throttle for emissions again and safety reasons to prevent detonation on poorly maintained vehicles)
Rear end gear/tire size changes (so speedometer is accurate)
Eliminate top speed limiter
Raised red line (shift points so I can rev higher)

For my next LT1 project I plan to use Ion at madz28.com for tuning. He is local to me and has competetive pricing and a good reputation & client base.

N0DIH
01-17-06, 02:23 PM
Yup, 11.2:1 rich on my truck. I call that pig rich!!

Driving the Cad today after the last 10 days on a trip in the truck with the new PCM is almost dissappointing! The LT1 used to run so much better, but the new crisp response of the truck is nice!!

Katshot
01-17-06, 02:25 PM
There's no doubt about it, if you have someone that has worked out his flash on a dyno, it's gonna be quick and easy for you. I guess I just like doing things myself. Plus, I never have to worry about paying for re-flashes.

N0DIH
01-17-06, 02:25 PM
If you can sit down with him personally I highly recommend it. The options are all there, he should know them well, Jesse really does VERY well, and you can do much that will tweak to your tastes.

I hope to get Jesse to copy my trans shifting routines so we can update my Suburban to shift more like the Cad. The Cad is setup for HD towing, and the Suburban needs to be....


... For my next LT1 project I plan to use Ion at madz28.com for tuning. He is local to me and has competetive pricing and a good reputation & client base.

Katshot
01-17-06, 02:42 PM
Changing the shift tables is easy. He can do a simple percentage change that will move the whole table proportionately. It's simpler than re-doing all the individual gears total profiles. I've found that simply raising the TCC enable speed (to 50mph in my case) does wonders for around-town driveability. That and a little extra timing advance.

N0DIH
01-17-06, 04:14 PM
My Cad has the factory tow package, and it enabled lockup around 37 mph, and 4th gear is locked out until 44 mph (45 w/AC on). How does this compare to non V4P cars? It is generally nice, but when you are crusing in traffic at 40-42 mph for a while, you wish you could get in OD. Else, it is a dream shift pattern.

I had him up the Suburban to 38 mph, but there is another table that we looked at and didn't change, I think that one might need it too.

Why did you choose LT1 edit vs say TunerCat or ??. Any advantages for it vs the others? I don't like how it locks you to a PCM.

Katshot
01-17-06, 04:24 PM
At the time when I got it, LT1-Edit was the most used by professionals. As I recall, guys like Bryan Herter used it for his re-flashes. Is it the BEST? I don't know. It looks like there's other applications that have come along that are easier to use but since I have this software, I'm not buying another one. If I ever get another car that needs this kind of thing, I'll evaluate what's out there now and make my choice. LT1-Edit has been easy to use and reliable for me. On top of that, the mailing list (LT1-Edit.com) has some of the most knowlegable guys I've ever seen, and they are always helpful to the beginner tuner.

N0DIH
01-17-06, 04:31 PM
I walked through a manual for LT1-Edit that was pretty comprehensive and that much sold me. I still haven't bought one yet. But should soon. Jesse uses TunerCat OBDII on my Suburban, but he doesn't like it much, says it is too buggy and crashes too much (which it did on mine when he was setting it up).

I don't know how stable TunerCat (non OBDII) is.

N0DIH
01-20-06, 12:16 AM
Has anyone used cables from this supplier for tuning?

http://www.pcmperformance.com/

They look like a good design.

Katshot
01-20-06, 09:25 AM
Got mine from:
http://akmcables.com/
Never had a problem with them.

BCs71
01-20-06, 01:49 PM
Got mine from:
http://akmcables.com/
Never had a problem with them.

Ditto!
:thumbsup:

N0DIH
01-20-06, 02:11 PM
I guess it seems pricey for less than $3 worth of electrical parts, a couple in wire and ?? on the connector(s). I am in electronics, so I am looking at it differently too (I do parts qualification for Component Engineering, as well as keep up on sourcing...).

I'll probably waste my time designing my own.... Doh!