Hi all,

Here I am here again asking some advice. Thank you in advance all and I appreciate your input.

I currently have the ecm 1226870 from a 1985 Corvette. This ecm if I read correctly is a 64k chip. This computer uses a MAF sensor and a MAFS module to control the power and burnoff functions for the MAFS.

In the 1986 cars two relays replaced the MAFS module and the Electronic Control Module (ECM) was changed to a GM Part # 1227165. which uses a 128k chip.

I have been told that the 1227165 is such a superior computer and if I had the chance to upgrade that I needed to. I do understand the larger memory on the chip gives it more responses for signals from the sensors but is it a truely big difference?

Car info:
Stock short block
trickflow heads
ported plenum, ported intake, and SLP rails
street/strip cam

I am truely humbled in this question as I do want to know opinions from everyone.

thanks,
Brian

 

The '85 '6870 ecm uses a 2732 eprom which is 4kb

The '86- '7165 ecm uses a 27c128 which is 16kb

 

Depends on what you want, or expect, to do. A few thoughts:
The 2732 Eprom's are no longer being produced (At least as far as I know..) and can be hard to find. No, I'm not real interested in selling any of the stash that I have hoarded...
The transmit frequency out to the ALDL connector is pretty slow on the older ECM, if you wanted to datalog info the newer box is a big step up.
Otherwise, the older ECM has a "bare prom" design, no CalPack and much easier to swap just the Prom chip in and out (the holders are a bit difficult to find, also...).
Either box actually Works (controls the A/F ratio and spark timing) just fine.
The editing masks for either of the chips are easily available.
The MAF control box (MAFS module) for the '85 is expensive, but has been described as "about as reliable as the Frame". You are unlikely to need one, and in reality none of the high flow aftermarket MAF's need the burnoff feature anyhow (they aren't hot wire designs) - all the circuit does is make the ECM happy and prevent a trouble code.
It's a fairly simple re-wiring job to swap the newer ECM into an '85 car - not a lot of work involved.
Bottom line - I'm happy with the "old" '6870 ECM in mine, but if/when it actually requires replacement because of a Failure then I'll probably step up and do the upgrade..

 

You can convert your ECM to use a modern flash memory chip such as a Atmel 29C256 or a SST 27SF256 using a adapter that can be soldered onto the board:

http://www.moates.net/g2-memory-adap...cing-p-36.html

 

You should not only use the 86-89 ECM, but you should also delete the 9th injector, and upgrade to 1989 software.

 

three guys drove to the moon and BACK with less computer than your 870. (ok they flew)
the first 300 mph quarter mile was run witn NO computer.
lotsa luck and lots of parts, a c4/5/6 MIGHT be able to keep up with a 69 z-28 that only has 302 ci and NO computer.
you already have more computer than you NEED, its the greasy stuff that is lacking.

only reason to switch to a -165 is availability for mods is better than the -870, parts and info.

 

I have done a LOT of research when I had my '85 to upgrade to a 165 ecm. I even have all the parts still to do the conversion, just decided to buy a newer vette instead.

First of all, there is NOTHING wrong with using the '870 ecm to tune your car and run it.. There is no MPG or performance gain from switchin to a newer ECM. IF anything it might be worse as the '165 ecm has more 'features' and tuning in it. The '870 ecm uses a very plain set of tables and settings which I think is actually easier to tune than the newer ecms (trust me, my '92 has tons more stuff to tweak than my '85 did in the ecm). The '870 ecm uses a MAF burnoff Relay box that sits under your passenger breadbox, the '165 uses two standard auto relays for the burnoff function which are cheaper to repalce than the burnoff module. BUT. my burnoff module never went bad on my '85, so not liek it's a problem part. Just expensive if you find one.

The reason I was going to switch to the '165 was due to the datalogging of it. The 870 goes into 'diagnostic mode' when datalogging the very limited data it shows (No knock sensor data which was a BIG plus during tuning) and that changes the engine parameters.

The '165 does not..

You can run into the 10's with a well-tuned MAF system, no matter what the ECM is..

 

Thanks so much!

You guys are wonderful! I sure appreciate all the responses. The responses make me feel much better about using this computer and I greatly appreciate the help.