ahusted

I really want to start burning my own proms for my winter beater 95 K1500, LO5, 5speed. (16196396 BDUY)
Because I am a newbie I'd like to grab a "spare" ecm from the junkyard. I have read the 7747 is similar if not the same.
Is there any reason that one is better than another? If they are the same, why did GM relabel the 7747 as a 6396 for 94 & 95 manual trucks?
I want to install a Moates G2 adapter to use with the Burn1. This way if I run into trouble, installing or burning, I won't have any downtime.

dimented24x7

iTrader: (2)

Nevermind, got my PNs mixed up.

Grumpy

They're not even close to being the same. There's generational differences between them.

If you want to do anything, then wait for the EBL, and use it. None of the GM TBI codes even come close to matching it. While it's still a few days away from being released, it's in it's own league......

You can use a ZIF in the EBL/ Ultimate TBI, and still use the Burn one or Ostrich.

Whatever you do, you want to carry a PnP replacement PCM/ECM, IMO...

dimented24x7

iTrader: (2)

...

dimented24x7

iTrader: (2)

Did the C3 really change that much with the new model years?

dimented24x7

iTrader: (2)

...

dimented24x7

iTrader: (2)

No offense to anyone, but I wouldnt be so sure about that...

RBob

iTrader: (1)

You should try it before commenting on it. . . Grumpy is telling it like it is. Not offended, have a smile on my face as I type this.

RBob.

{edit: according to Ludis's site the 16196396 ECM is a C3, no trans control. Must be the last of the last in that series. There is also a good possibility the EBL setup is a bolt on for the ECM (well, at least a solder in).

dimented24x7

iTrader: (2)

Maybe it should have read: None of the C3 tbi codes even come close.

While Im not doubting you in any way, the P6s have some really cool stuff in them. While it retains some of the core subroutines, GM finally ditched the faux PID routines for actual PID routines and greatly improved all the rest of the code. Its quite sophisticated. Each of the major routines could easily swallow up the entire processing capacity of a C3 and hardware wise its the best 8 bit computer out there. Probably the biggest departure, aside from the trans control, was the idle routine. Actual flow based PID control with additional idle control present in the spark and fuel routines. Any chance this will be the future of U-TBI?

As for the 6396, anyone have any pics? It looks as though it at least has a different connector. It appears to use the two red/blue 32 pin connectors like the other PCMs. Its surprising that they would use a C3, since the PCM is set up to use a manual, and also has specific logic just for when a manual is present.

dimented24x7

iTrader: (2)

The pinouts for the '6396 given on diy-EFI show it as being a standard PCM with the manual options selected.

If thats the case, then youll need a G1. No mods required to burn proms with the pcm, if thats what youll be using. Just bang the memcal into the adaptor and burn away.

Edit: Easiest way to check is to pull it and pop the cover. If theres a blue memcal, then you know its a PCM.

JPrevost

Dim, you do know that no matter how sophisticated a piece of code is, it's only as good as it's programmer. The programmer NOT being GM but in our case, the DIYer. What good is having a bunch of large tables that adjust the idle speed when a few tables do the same job while making quick work of the tuning? I'd go with the KISS approach.

dimented24x7

iTrader: (2)

These arnt a few tables. Its a complete Proportional Integral Derivative control routine based on actual airflow, and not IAC counts. This means complete linear control over the idle. With the old routines, just some form of GM integral and proportional control was given. This would still not address the problems of small variations in RPMs and the need to tone down the gain since theres no derivative term to assist.

Yeah, the KISS approach works, but its rough around the edges. With the idle routine in the old computer it would target and reach the desired RPM range ok, but it was powerless to control those small variations and transients. Always annoyed me that the tach would flutter slightly while newer cars have a rock solid idle, which is made possible by the newer logic.

Alot of whats in this PCM is likely to be similar to some of whats in the newer stuff today, and I think we'd be screwing ourselves over in the long run if we didnt at least look at it and get some idea for how things are being handled now.

Ok, Im done with the soap box. Who wants it next?

ahusted

I'll try to get some specific ones if you want.

ahusted

continued

ahusted

Its an eprom, not a memcal......?

dimented24x7

iTrader: (2)

The stuff on DIY-EFI is wrong then.

It looks like a plain old C3, same as the 7747. If your going the u-tbi route then any C3 ecm will do. 8062, 8063, 8746, 7747, theyll all work for that.

As far as burning proms goes, the only difference with those ecms is the code thats on the rom. Its different. Youd have to find out what mask is running on the ECM. If its the $42 like the 7747 has, then a 7747 will work and your prom will interchange between them.

dimented24x7

iTrader: (2)

I doubt its the same mask as teh 7747, but reading the chip will tell you for sure.

dimented24x7

iTrader: (2)

The mask ID for the BDUY is $9A, so there probably isnt much info available for it and a 7747 wont be compatable in stock form. If you where going to stick with a stock ECM, the 7747 would be the best bet. Theres alot more info available for it.

ahusted

Thanks!! I'm still green so I need to do somemore reading before I really get started. But I think that I can keep my 6396 intact for my "spare" and grab a 7747 to install the G2 and maybe later the EBL. I saw a truck in the yard that was the same set up only a '91. Would that be a good starting point? I should be able to use the 7747 burn a bin for an older truck and start datalogging from there, right?

Grumpy

Have you run it?, or just speculating?.
I'm talking from experience.
And I am sure about it.

Grumpy

Only as far as the *E* tranny control end of it goes, the engine stuff still is less then optimum.
Again, BTDT, no guessing involved.

Grumpy

Correct, that is an EPROM.

Grumpy

Datalog what you have.
Idle, start-up, cruise, WOT, and not just a few seconds worth, do it at different temps..

If you had an editor that you could read the old one, that'd have been nice, but without it, you just have to start frim scratch with your new ecm.

Then with that as a baseline install your new ecm, and data log it, and compare the two.

You're going to have to compare the two ecms pinouts, before assuming their Plug and play compatible. One wire difference can smoke an ecm, and I mean smoke,

If you have to repin the harness, then carry a 747 for a spare with a known good limp home mode eprom in it.

dimented24x7

iTrader: (2)

Im not speculating, and Im sure itll live up to all expectaions. RBob knows what hes doing.

But... There are some inherent limitations to the C3 ECM. Processing power is limited and theres only so much time available. That places some limits on what code can be run on one. I really liked the C3, but it was just too limited. I couldnt do the things I wanted to do with it, so thats why I decided to migrate to the PCM. As complicated as the code is, it makes alot of sense. Will it be hard to tune? Im sure itll be a pain, but it has the potential to make for a vary nice running engine.

Similarly, how can you comment on that when no one even knows whats in the PCMs? The hacs certainly dont say. I have a feeling that whats running on the PCMs engine wise is similar in part, but less complex, then whats running on modern LS1 PCMs. Looking at a preview that LS1-edit gives, it doesnt even look like theyre scratching the surface of whats really in the PCM, so Id like to at least get a brief introduction to whats going on inside one.

ahusted

I must be blind.... I looked around for pinouts for the 7747 and 6396. I didn't expect to find anything for the 6396, but the 7747 seems well documented...
Can anyone point me in the right direction?

dimented24x7

iTrader: (2)

You could probably look at the colors of the wires in the 7747 connectors and compare them to your harness. I cant see them being that much different.

Its sort of odd that they even continued to use it for that long. Maybe they had some left over from production.

yager

Just doing my daily reading and saw this. My 1995 C2500 also has this ECM in it along with a BDUZ chip.

I havn't found a TP xdf yet but have found some commneted hacks for several of the $9A and was going to make up a simple xdf for basic tuning.

I was planning to drive the truck to work at the end of the week to do some datalogging and see what things look like. I have some poor mpg i hope i can fix with a sensor or 2, if not some programing...

zapeee

For whatever it's worth, I replaced the 5.7 and 16196396 BDUY in my 1995 GMC yukon 5-speed with the 7.4 and 1227747 ARAP from my 1988 k3500 4 speed. i did not change the wiring harness, but had to re-pin my IAC and TPS connectors. everything seems to work OK except for my ABS, (just in here trying to figure out if it's related.)

BTW, neither truck would run right by just swapping chips!