Was just curious which ECM i should use with this setup. I have both the 305TPI with 5spd ecm and the 350TPI with auto ecm. And i currently have a 350TPI with a 5spd. I was assuming just use the 350 and deal with the shift light coming on all the time? Any info would help thanks.

 

If you have a MAF setup (1986 to 1989) and the 350 is stock or close to it you will be fine with the 305 chip. The MAF system tends to be a little more forgiving in the tune area as long as its close. If you have many mods even the 350 chip will not have the proper tune.

I'm not sure what to tell you if you have a SD setup (1990 to 1992).

Tell us more about your car so we will have a better idea of what your dealing with.

 

The transmission affects it more than the engine size does. I used a 91 305 5-speed 19lbs injectors chip with my 350 5-speed 22lbs injectors engine with no problems.

An automatic tranny chip with a 5-speed tranny usually causes the engine to stall a lot, because the idle settings arent high enough.

 

Its completely stock for now and i do have the 305 chip in it but for some reason it smells like its running a bit rich. Ive only had the car for about 5 days and im not too familiar with tpis yet but im trying to learn. Id like to just do mild mods and hopefully tune it soon. So the the stock chip is just temporary but I do want to make sure its running properly. I noticed the idle seems to change a little bit, but im not sure if thats do to the chip or not. I did get the car in Montana and I live in Colorado so im not sure if the maf needs some time to adjust to the altitude either?

 

don't you have that backwards? Auto Prom is what, 750rpms and the T5 prom is 450rpms, so a T5 with an auto prom is fine, it's an auto with a T5 prom that will have issues.
btw, I ran with an auto prom in my car for about 18 months since I was too lazy to reprogram it.

 

I dont have my tuning software on my home computer, but I dont remember seeing any T5 PROM with an idle of 450 rpms.

But I have read lots of stories from people on this board complaining about their new T5 swap stalling a lot because of the automatic chip in it.

 

I just looked at my service manual, and I am incorrect.
Minumum idle is 400 rpm for 5L (F) and 450 rpm for 5.7L(8) in Nuetral for both auto and manual transmissions.
Now, I believe target idle is a tad higher.