Few questions on my 1st LT1 tune

[steveo]

sometimes flash memory just dies. it's not super awesome flash memory

definitely get a spare ecm

but keep in mind i flashed mine at least 1000 times, and before i had it, it was an exchange ecm from a tuning shop so godknows how many times it'd been flashed before.

[JustinSEO]

Gosh, my current tune is trash compared to my old one.... The car is running higher RPM maybe from the TCC problems; The speedo is way off, the BLMs are all over....

Someone link me to a stock 94 bin? I have been looking for one....

Here is a copy of my datalog, if you wish to take a look plz do; seems like the car is running kind of rough.

[sherlock9c1]

I can lend a bit of advice on transmission tuning as I have had LT1/4L60Es for a long time.

1. The 4L60E has no built-in pressure sensor to provide feedback to the PCM, so all it can do is gauge shifts based on time. Just like you bought a wideband, buy a transmission pressure gauge and drive around for a few weeks with the gauge strapped to your windshield wiper like a hood tach so you can get an idea of what it's really doing pressure-wise. Ebay seller cmbclalb sells a good one that I've used for a long time. A healthy 4L60E will have around 70psi at idle in Park, Neutral or Drive, and climb to around 150psi in reverse. You should see over 200psi at WOT at some point in 1st gear.
2. Think of line pressure tuning as two separate regions; during shifts, and between shifts. If the trans is not slipping in gear, then leave the line pressure tables alone and ONLY reduce the "Shift time (sec) vs. TPS vs. shift." In the last LT1/4L60E I tuned, the WOT shifts were perfect at 0.600 sec for 1-2 and 0.875 sec for 2-3. Leave the 3-4 shift at 0.00 seconds because the 4th gear apply piston is small and needs no softening. That 1-2 shift value gave me just a slight chirp from the rear tires. I tried 0.400 sec but it was too harsh and barked the tires. 0.800 sec wasn't firm enough and was actually cutting pressure during the shift according to Datamaster.
3. The 4L60E is a bit of a hybrid transmission in that the shift solenoids command the START of the shifts, but the actual shifting is still completed by hydraulic valves, unlike something like the Chrysler 41TE where the solenoids directly fill the hydraulic circuits with no additional valves. Sometimes these shifts take a long time to complete, so if you're hitting the rev limiter and you have sufficient line pressure during the shifts, you need to reduce the shift MPH to get the shift to complete on time. A looser converter, numerically lower rear axle, more engine torque, and more vehicle weight will all exacerbate this late shift behavior.
4. Shifting harder IS shifting faster, and vice versa. It's really a balance point. For modded vehicles, the only way to get your 4L60E shifting perfect assuming it's in good mechanical health is to dial it in over the course of a datalogging/tuning session, or in my case, a road trip.
5. No need to up line pressure with a looser converter unless you think it's slipping. The easiest way to do this is to reduce the "maximum line pressure" scalar 5-10% which will give you 5-10% more pressure across the board at part throttle, but it will NOT give you any more at WOT once the sum of the line pressure tables equals or exceeds the scalar.

[kur4o]

You can try this bin.
It`s 94 a4, 3.23 gears, stock file.
Cal id is 16210011 wich is the latest update fix for your vin

Your stock bin information
Vin 2G1FP22P4R2121999
CAL id 16199611

Check yourself here:

https://tis2web.service.gm.com/tis2web

[JustinSEO]

Can I open two tuner pro and copy values from my old EEB 94 bin into my 95 pcm and flash them to it? Use difference tool to see what needs to change and simply change them all?

[lionelhutz]

You can use the difference tool but you have to make sure you don't copy the data that is mapped wrong and is bad.

I'm not sure why you're stuck on a 95 bin. The PCM doesn't care which year of bin you use and there was a 94 bin posted for you.

[JustinSEO]

I'm not stuck on it just sketched out because of that checksum error I seen before; I believe that is what caused all of this.... I know I seen something about a checksum popup before the killer flash was uploaded.

Thanks a ton for that bin, it worked great... I took the chance tonight without a spare and went ahead and flashed the 94 tune you supplied; my torque converter is now locking up like it should, and my speedo isn't 15mph off still.... and most importantly my shift points are back I can actually cruise at 2200rpm instead of 2800...

Now I just wish I would have went ahead and lowered those fan temps, applied the WOT BLM Locker and maybe even dropped the shift points a little more to help with the slapping rev limiter; also sometimes when it kicks down it slaps rev limiter then goes to next gear, I need that tuned out... I guess now that I know I can do it myself I will have to make some more changes and flash my spare when I get it... definitely will want a new spare.

Do you guys know anyone who fixes bad PCMs?

[kur4o]

With 3500 rpm stall torque converter, upshifts doesn`t work because of the stall wall.
It`s known problem with the lt1 pcm.
Do some google search how to fix that and post the working formula.

Transmission is different between 94 and 95 and you shouldn`t mix bins.

[JustinSEO]

With 3500 rpm stall torque converter, upshifts doesn`t work because of the stall wall.
It`s known problem with the lt1 pcm.
Do some google search how to fix that and post the working formula.

Transmission is different between 94 and 95 and you shouldn`t mix bins.

That is what I was thinking, the stall definitely has a part to play in that. I will do some checking, and probably talk with Keith of PCMFORLESS to see what they do for large stalls like that if he'll share!

I didn't mix the bins, I wanted to copy values over but it is not necessary now that I have a stock 94 bin that is up-to-date... I don't think I have ever clenched my cheeks so tight while watching that flash; haha.