1987 Fiero GT: 7170 tune or 7730 swap?

**MarkW** · 07-02-2020

Hello! Thanks for letting me join the forum! I've been working on cars for most of my life, but am new to EFI. My current project is a 1987 Fiero GT that I'm pretty sure just needs some tuning to correct a hunting idle. Somebody has accessed the minimum airflow screw and back-probing the TPS has been giving odd results, thinking I may have to burn a chip to fix the open loop fuel table since apparently they were lean from the factory. A 7730 swap may be in the future since the cold-start injector is dead and a replacement can't be located, but I'm worried about adding a knock sensor since I've seen where people have had issues with that. I've got the .XDF, and .ADS for the $24 mask, TunerPro RT, and my ALDL to USB cable should be in tomorrow. Any advice for getting started would be appreciated!

Will be starting a TBI to TPI swap on a 1991 Firebird Formula after finishing this project - could kick my own ass for pulling the TPI system off an 85 though.

**1project2many** · 07-02-2020

Hello,

You've posed an interesting set of questions. Generally swapping to a newer ecm rewards you with better driveability and the 7730 is a good ecm. Doesn't the Fiero use a knock sensor now? Most of the C3 ecms used a knock sensor but I suppose anything's possible. How long would it take to get the swap completed? If you can get replacement chips or an emulator then tuning the 7170 might be a good beginner project.

**MarkW** · 07-05-2020

Strangely none of the v6 Fieros came with a knock sensor, though apparently you can add one to the 1985 if you source a filter module and change a flag on the chip - you could just wire in a wideband on that year too. That method seems to yield good results. The 7730 shouldn't take too long, from what I can tell you have to re-pin some stuff, add six wires and burn a chip? It's pretty well documented luckily ( http://www.gmtuners.com/files/index.htm , http://www.fiero.nl/forum/Archives/A...-2-079574.html ). I've seen a few people struggling with false knocks after the swap though, maybe something the do with the 3.1L $88 mask?

I spent a good part of the day trying to pull data from the 7170 ECM without any luck. I'm using the Red Devil River USB to ALDL with the 10K resister in loop, though I tried it both ways. The cable passes the check in TunerPro 5 and I tried several different .avx and .avs files, but nothing from the ECM in TunerPro or WinALDL. I'm thinking I may have to pick up a serial based cable and laptop with a good serial to deal with the 160 baud? Would it be worth trying TunerPro 4 to run the .avs without converting?

**1project2many** · 07-12-2020

I have no experience with the Red Devil tool. If you have another OBD1 vehicle you could try to confirm your software and hardware setup. All future diagnosis should include the knowledge that you have a working setup.

I just remembered that some of the '165 ecm's route data to a different pin in the ALDL connector. Is it possible yours is the same way?