Svelte_SS

My car is running like @$$ and I've replaced all the ign. parts, tested all the sensors, cleaned all the passageways, and done everything else suggested on this board to no avail so I'm now going to tackle the ECM. So long story short I'm pretty sure my ECM is burned out because it doesn't work with scanners. etc and I'm going to replace it anyway with a new one and start burning my own proms.

OK let's start at the beginning. I bought a 1985 IROC with a 305 TPI in it. Well long story short I took it to the dealer and the block was cracked. Well they went ahead and replaced it with a GM Goodwrench 350 because they are more plentiful and cheaper than the 305. So now I have a 350 being run by a 305 ECM. Well long story short I dropped the whole thing into my 87 Monte Carlo SS. So now I have a 305 IROC ECM trying to work with my Monte #'s like weight, wheelbase, gear ratios, tranny, etc.

My question is what ECM would be best to start over with? I know the '87 IROC's and up went to the 350 so would an '87 ECM drop in and work with my '85 wiring harness? Or would it just be better to get another stock '85 ECM and start the tuning in the PROM? Another question, can I edit all the #'s I stated above in tunercat (and disable my smog/EGR) in it too or do I have to learn assembly and start compiling .bins?

Thanks...

Bort62

First off, the ECM doesnt care what car it is in - So that has nothing to do with your problems.

if the ECM won't connect to the scanner, and everything is hooked up properly, either the ECM is cooked or the memcal / Prom is not inserted properly.

Regardless, the 85 ECM is a peice of junk anyway - unfortuantely it is not plug and play to swap in anything.

Your going to have to repin If you want to swap to a later MAF ECM, but if your gonna Repin the damn thing anyway, You might as well Go ahead and swap in a Speed Density setup. It will make your Tuning much easier.

Svelte_SS

^

Bort62

What part of your question Did I not answer ?

Maybe that is why you got no other replies - because there is nothing else to add.

Aron213

reread what Bort said, the 85 ECM is junk, 86-89 uses the same ECM 165, doesnt care if its a 305 or 350 then ther is the 730 used in 90 to 92 which is speed density and easier to tune with more options available for tuning!

Svelte_SS

What is it about the '85 ECM that makes it junk? Basically I was wondering what would be a good starting point for me on this and I had some other tuning questions. I guess I'm going to find a '90-'92 ECM and go from there. But now a couple more questions:

-Are all 730 ECM's the same? Can I just get one off ebay or do I have to look for one specifically out of a '90-'92 car?

-I have no idea how to mount a knock sensor for the swap. Does anyone who's done this have any input?

thankx guys

ctandc

Here's my 2 cents.

The reason the 85 only TPI ECM is junk is the fact it's ALOT slower in it's data processing abilities than the '165 ECM that came out the following year in '86. Don't feel bad, my 85 IROC has that ECM as well.


Mike Davis' Site


Start reading...he started with the 85 '870 ECM setup, and swapped to a '165 ECM setup. I plan on doing this as well. He also shows how to swap to the SD setup.


As far as which is "better".....I plan on swapping to the 165 ECM. It only involves moving some wires around on the harness at the ECM, adding a couple, removing a couple, and adding two relays. Mike covers ALL the needed info on his site.

The reason I'm going with the 165 is the simple fact that, while I'm certainly not new to cars, I'm new to burning my own PROM's, and from a "get it running" standpoint, the MAF systems are MUCH more forgiving on a setup that's modified from stock. You will hear lots of issues about how the SD systems are better for higher HP, better for tuning, but almost ALL the people who are saying this, started tuning on MAF 165 systems. The MAF system is much more forgiving if you need to have the car running quickly, like I do, since it's my daily driver. SD systems are much more "tweakable" when tuning, especially heavily modified engines.

Now what you do, is solely up to you...but like I stated, I plan on swapping to the '165 ECM, which is not expensive to do, the only parts you need are the ECM w/ PROM, (2) relays ( these replace that bulky, WAY overpriced one year only MAF BURN off box that's piggybacked to your ECM you have now ), some wire, and that's about it. You can use the existing knock sensor as well. Another benefit to the 165 ECM, if you shop around, you can score a ECM w/ a 5.7 TPI PROM, and your engine should run nicely out of the gate, especially if it's close to stock.

A few things to watch for....

Later model 165 ECM's got VATS, and your Monte doesn't have it...it CAN be added, but to me it's not worth hassle. You'll also need to know if the ECM / PROM you buy has the cold start injector, which went away in '89, it's function was moved into the program of the PROM itself....physically, you can just unplug the harness from your cold start injector, and it won't be a problem, then later get a CSI plug kit if you want to.

The quickest and easiest route, ESPECIALLY if you plan on burning your own PROM's is to go ahead and acquire all the things you're going to need BEFORE you do that swap. That way, especially if you use Tunercat, it's a very simple matter of disabling VATS in the chip.

- Cable for hooking to ALDL diagnostic port up to a laptop with a "Scanner" type software loaded. You can use a scanner, but the price of a good scanner with data capturing ability ( which you'll need to effectively tune and burn PROMS ) is normally about the same price as everything you could by below

- Cheap Laptop

- diagnostic software for above.....Craig Moates has some, alot are free to use. SEARCH the DIY / PROM board for alot of areas to explore...mainly personaly preference here.

- PROM burner - again, SEARCH...I plan on a Pocket Programmer 2

- You need an adapter that allows you to easily change PROM'S, I recommend the Craig Moates adapter, he even has a package that includes the adapter and spare PROM'S for burning


- Spare PROM'S

- You'll need a software program that knows how to READ the info on the PROM, and thus allows you to change the things you want........the initial changes are SIMPLE , ON / OFF switches inside the PROM.....I plan in using Tunercat, alot seem to like it as well.


My advise is to surf through the DIY / PROM archives, and do searches on "TunerCar" "165" "870" etc......LOTS of reading and you'll LEARN alot. Several members have also written awesome articles on getting started burning your own........




HTH