I just bought a 85 Iroc a couple of weeks ago with 305 TPI.I have a 355ci engine with aluminum heads that I plan on installing.Would I be better off installing a ECM and harness from a 86-89 Iroc or would I be able to tune it good with the 1985 ECM.I plan on burning my own proms in the future.

 

There are advantages to changing to the later MAF ECM (165), and running the 1989 bins. They are better defined and better known. However, there are also people running the 1985 MAF with heavily modified engines and have found very good results with there 85 MAF system. They feel changing to the 165 isn't worth it.

Since you are gettng the equipment, may I suggest trying to work with your 85 ECM/bin first. Then, if you are not getting the results you are seeking, change over to the 165 at that point. The only cost if you should chose to change to the 165 ECM later is the time and/or money you spent for the 1985 MAF definition.

And that is totally dependent on the Bin Editor you plan to use. If you are using TunerCat, you are talking $20. I not sure about TunerPro, but I believe there is no cost...but I don't know who well the 1985 MAF system is defined in TunerPro. I'm sure someone will fill you in on TunerPro.

 

Thanks for the info Grim Reaper.If I decide to go with the 165 ECM would the engine harness need to be swapped also?

 

http://www.eecis.udel.edu/~davis/z28/ecm_swap/

Go to the above link. It discusses swapping the 1985 MAF ECM (870) to the later 1986-89 MAF ECM (165).