be easy on me guys i am new to this car computer scene..............i am gonna be building a 3.4 v6 for my 1991 MFI camaro

i need to know what will need to be modified in the computer for these changes: forged pistons with 10.5 to 1 compression, large cam, roller rockers...........any help would be cool,........be easy on me though

 

You have basically two main problems as I see it with a late model V6 3rd Gen.

1) You have SD, so you will need a custom eprom to make it run correctly. You have a 10% increase in displacement plus your VE is probably different between the 3.4 and 3.1. Really depends on your camshaft selection.

2) Very little information is known about the "404" used in the late model V6 ECM in 3rd Gens. Why GM did not use the 7730 like many of the other 3.1s is anybody's guess.

If GM had used a 7730, then you could have modified the $8D BINs to work for your V6 as there is a "# of cylinder selection" available on the $8D.

I have not been able to find a "hac", a bin or even a "definition" for the 404 used by F-body 3rd Gens. I am not saying they don't exist, but they are not readily available.

If I had a V6 and was able to read the Memcal, then I MAY be able to shed more light as whether you have any "easy" options.

One option that I CAN think of, is to convert to a 7730 like the SD TPI cars (and lots of other 3.1 V6s use). And then modify a SD TPI BIN by setting the "# of cylinder selct", injector size and displacement accordingly. At least, THEN you could modify your eprom EXACTLY like us SD TPI guys do...and speak our same langauge too.

Until I find more information on the 404 ECM used on 3.1 V6 3rd Gen F-bodies, this is the best suggestion I can make at this time.

If anyone else has a better suggestion or more information, please share.

 

There is a mini hac of one of the 6 cyl 730 cars floating around it's nothing like the 8D. For the 9 months work that goes into doing a hac, and in all this time, I doubt there will be one. So yes the 730 is going to be the only option. yes it will take work to get right.

 

Well, now that Bruce has spoken and recommends the 7730 route also, I can offer you something if you wish to consider this route.

I do have a 1991 Factory GM shop manual that has all the wiring diagrams for the pin connectors for the 404 and 7730 ECMs. I would be happy to photocopy the relevant sections and fire off a copy if you (or some other 3.1 V6 user) wanted to look into the conversion.

Also, I am quite familiar with the $8D Bin and I would be happy to assist in identifying things that would need to be changed to make the $8D Bin work on a V6.

My only request is that this be done publicly on the DIY Prom Board so the information is shared with everyone and that the "draft" BIN be submitted to DIY-EFI.ORG so others may have a starting point.

Your ultimate "final" BIN would be yours to do with as you want, as you will ultimately tweak it for the uniqueness of your application.

PS: I am NOT saying I will "draft" the Bin for you...just identify constants and tables that will need to be adjusted to work and assist you (and any other V6 user) in making the modifications.

Also, thanks for even considering writing your own eprom for your V6. I REALLY would like to come up with a solution for all the V6 guys, so writing an eprom is as common for a V6 as it is for a V8.

[This message has been edited by Glenn91L98GTA (edited August 06, 2001).]