16197429 Documentation Project

[RobertISaar]

the 7429 is the PCM from the 93-95 northstar cars, while it's in my posession, i'm going to try and document as much of the hardware as possible.

these are P66 PCMs with both 68HC11F1s on a single board. two 27C512 PROMs in a single MEMCAL with a modified P4 knock filter.

3 32 pin connectors, of which only 6 pins aren't used in some form in any factory application. these things are LOADED with hardware, a total of 41 ICs, most of which i can't identify yet.

interesting stuff found so far: there are 8 FETs used that drive the injectors, there is another identical FET right by them so i was curious to see what it does. it's output runs through a large 1 ohm, 1% resistor and goes on to power the pressure control solenoid in the 4T80E. marked as a 9395, most likely an IRF9395.

i'll probably have some pics up tomorrow.

[The Dark Side of Will]

the 7429 is the PCM from the 93-95 northstar cars, while it's in my posession, i'm going to try and document as much of the hardware as possible.

these are P66 PCMs with both 68HC11F1s on a single board. two 27C512 PROMs in a single MEMCAL with a modified P4 knock filter.

3 32 pin connectors, of which only 6 pins aren't used in some form in any factory application. these things are LOADED with hardware, a total of 41 ICs, most of which i can't identify yet.

interesting stuff found so far: there are 8 FETs used that drive the injectors, there is another identical FET right by them so i was curious to see what it does. it's output runs through a large 1 ohm, 1% resistor and goes on to power the pressure control solenoid in the 4T80E. marked as a 9395, most likely an IRF9395.

i'll probably have some pics up tomorrow.

Cool! Good luck, man.

I have a Northstar Fiero and was using that computer for a while. I took some reasonably high res shots of the board... Not that it's a lot of work, but I could probably dig them up for you.
There's certainly a lot of stuff in the unit. The board is at least 5 layers.

I also have a dyno-only calibration that was snuck out of GM. It ran the engine without automatic (my swap is a stickshift) fairly well. Only problems were stall when sinking the clutch from overrun and running just a little bit rich. The BLM's were disabled, too.

[RobertISaar]

i took a few shots using the wife's T3(12.2MP DSLR) that way i could start labeling stuff as i discovered it's usage. i do need to take more though, especially at least one on the backside. there are a lot of tiny SMT resistors on the back.

i don't think i'll be able to get this down to the Ludis level of completion, but it will be more than what is known about it already.

that calibration..... happen to know if it was built off of the 93, 94 or 95 codebase? IIRC, they were all slightly different compared to each other.

[RobertISaar]

in my search for info:

http://www.retro.co.za/efi/DIY_EFI/1999/efi4-206.txt

found that the 94-95 LT1 PCM uses some common ICs as well. i've determined that the 129170 chip seems to be the injector controller, the LT1 uses it as well. based on the date code, i'm assumg it's first application were the cadillac V8s that ran SFI.

the LT1 also uses a crystal that causes the processors to run at 3.15MHz instead of the normal 2.1MHz that the P4s and this P66 unit does.

[The Dark Side of Will]

that calibration..... happen to know if it was built off of the 93, 94 or 95 codebase? IIRC, they were all slightly different compared to each other.

No idea... The .bins were on the DIY-EFI FTP site as of several years ago. I still have them as well, but would probably take me some time to dig them up.

[RobertISaar]

hmm..... weird. happen to remember a filename?

[The Dark Side of Will]

Would have had "Northstar" and "A" in one filename and "Northstar" and "B" in the other... might also search for variants of 16197429.

[EagleMark]

two 27C512 PROMs in a single MEMCAL with a modified P4 knock filter.

Don't think I've ever seen that Memcal. Are you thinking this PCM is a cure for I/O and space room your having with nAsty1?

[RobertISaar]

it is one of the potential candidates.

and the MEMCAL certainly is unique... technically, the two missing pins on the knock filter aren't supposed to do anything. and the two on the far left don't either, they're for support, just like the P4 filter. the important 4 pins are on the right.

[RobertISaar]

i had forgotten how nice it was to work with a part that has nice documentation from it's creator... the pink book is an absolute goldmine of info for any P6/P66 application.

A/D channels on E and T side

E-side
ch0 = MAP
ch1 = TPS
ch2 = none?
ch3 = ignition voltage
ch4 = right/rear O2 sensor
ch5 = left/front O2 sensor
ch6 = trans temp
ch7 = EGR position

T-side
ch0 = PCS measure
ch1 = cruise servo position
ch2 = power steering pressure switch(read as a sensor?)
ch3 = coolant temp
ch4 = ignition voltage
ch5 = MAP
ch6 = ???
ch7 = TPS

T-side channel 6 is used for something, but i haven't traced the circuit yet to find out what. E-side channel 2 doesn't ever appear to be read?

EDIT: there may be more.... i don't see IAT in that group.

[EagleMark]

That Memcal is cool looking. But no netres?

[RobertISaar]

correct. i don't know if there is a limp-home function at all on this PCM, haven't gotten that deep into it yet.

also, one of the chips on-board was used in P4s for a mux'd a/d channel, i get the feeling it is used that way here as well.