Hello all,
Yes I'm a new member. And have no respect by the dedicated members here. Hopefully I can get some kind of help anyway?

I did a v8 swap into my 1995 S10 ext can pickup.
Donor car was a 1990 Caprice 305 w/ 200 4r tranny.
ECM service #1228746

Truck is running on the ECM fine. However my rear gear ratio on the truck is a 3.42 gear & 18" wheels making my end ratio 3.71 gear.
So you can guess the shift & power band is wrong on the eprom for this setup.

What I'm wanting to know is... there a compatible eprom I can get that will work in my ECM that is programmed with a 3.73 gear?
If there is a swappable chip. Can any of you gentlemen give me the number on the chip. The ECM service number and what vehicle I can find it in please?

If not, can my eprom be flashed to the 3.73 gear spec?

Thank anyone in advanced for your time.

 

No one has any kind of information?

 

Hello all,
Yes I'm a new member. And have no respect by the dedicated members here. Hopefully I can get some kind of help anyway?

I did a v8 swap into my 1995 S10 ext can pickup.
Donor car was a 1990 Caprice 305 w/ 200 4r tranny.
ECM service #1228746

Truck is running on the ECM fine. However my rear gear ratio on the truck is a 3.42 gear & 18" wheels making my end ratio 3.71 gear.
So you can guess the shift & power band is wrong on the eprom for this setup.

What I'm wanting to know is... there a compatible eprom I can get that will work in my ECM that is programmed with a 3.73 gear?
If there is a swappable chip. Can any of you gentlemen give me the number on the chip. The ECM service number and what vehicle I can find it in please?

If not, can my eprom be flashed to the 3.73 gear spec?

Thank anyone in advanced for your time.

 

try reading this post

 

What post are you referring to?

 

Do you have a VSS on transmission? I think 1990 Caprice still had it in back of Speedometer and a DRAC.

Without it the TCC will not work, but for shifting the TC cable to trans needs to be adjusted properly.

There is no gearing or speedo changes in the chip.

 

It has vss on the back of the speedo. However I don't think there was a drac.
The vss on the back of the speedo is a 2 pulse vss and it converts the signal to a square wave then goes to the ecm.
I'm trying to find out. Since the trans shift is controlled by the governor.
The vss just let's the ecm know when the vehicle is moving so it can adjust fuel/air ratio and lock the torque converter.
So it seems all I need to do is put the correct drive & driven gear so the speedo matches vehicle speed.

Does that make sense?

 

Yes that does make sense. You have to drop the pan on the 200-4R to change the speedometer gears. Good luck finding them.

 

If a swapper were running a 305 with '746 ECM from a 1990 Firebird and a 1989 Turbo Trans Am 200-4R, one way to make it work when using it in an electric speedo car like an 86-up Firebird or 90-up Camaro would be to use a 1989 TTA VSS (there is no reluctor wheel style VSS setup for a 200-4R) and wire it like one too. They have a signal going from the speedo-gear driven VSS to a buffer box which feeds the ECM, cruise, and speedo.

Correcting for rear gear or tire size changes in any case for the 200-4R would be done through speedo gears.

The recipient 1995 vehicle may have onboard buffer / splitter hardware or it may not.