Question : First post question about issues with 3.4 Fiero

[ncoop23]

Hello,

I just bought a 84 Fiero SE with a 3.4 DOHC in it and it isn't running right and need some help getting her running strong. It cranks for 10 seconds to start and when it starts it idles high ~3k till it gets warm then I have to turn it off and back on to get the idle down. After i restart it, it idles fine at 1k with some initial fluctuations. Sometimes when I start it a big cloud of smoke comes out the exhaust also. When I get on the gas hard it kind of stumbles on acceleration like it is going from full to half power. Anyone have ideas on things I should check? It is a wiring nightmare and there are some oddities to the wiring like a box with 4 injectors in it hooked into the wiring harness and a box with a switched 555 timer circuit. (Passkey defeat?) So yeah it's a fun car but I need to get it running right as it is getting like 7 MPG right now and I want to get it going before I store her for the winter.

Any help would be greatly appreciated.

[86FieroSEv6]

Well, for starters, check out the ECM and let us know what the service number is. The more details you can provide, the better we will be able to help.

[ncoop23]

Injectors 17090844
ECU 16196401 BHZW

[ncoop23]

Well bigger problems now... On shifting into 2nd, I broke a chunk off of my engine block... The guy who owned the car before me hacked the upper engine mount and now I need to figure that out. Any ideas on the high idle though?

[FerrariFan]

Welcome to the wonderful world of Fiero engine swapping. Now you know why you got such a good deal on the car! LOL
Seriously though, There is almost no way to diagnose this over the internet. You need to find out what year the engine and computer are. What code is the ECM running? Is it MAF or MAP based. Most of the users of this website have cars with their original engines. I would start by searching over at Pennocks for more info on this swap www.fiero.nl
Once you find out what year engine and PCM you have you need to get the wiring diagrams for each and sort out your wiring harness. make sure all the wires are going to the right places and that all the connections are soldered and heat shrinked.
After that you can start troubleshooting the DTC's with a scantool or software like TunerPro. Check out moates.net for tuning tools.
Good luck!

[Fierobuffoon]

wow what a mess he has... almost better off with a 2bbl carb and a 2.8 distributor from an s=10.. thats a horrible wiring and engine mount mess he has.

[ncoop23]

Ok so I put the car away for the winter and go it out earlier in the year. The TB was chewed up but not snapped. Put a new belt on and same issue.

After some diagnosing, the car has spark but no injector pulse. Any ideas on what may cause this?

Thanks for the help guys.

[ncoop23]

Got her going, was a blown inline fuse and a wire that was pulled out of a connector. Gotta love them little things!

[WrathOfSocrus]

Grats on getting it running! There are few things harder to fix on a car than a wiring job done by someone else.At least with hard parts it is pretty easy to find what is wrong and repair or replace. With the 'brain' under the hood it is easy to have one wire or connector issue that could potentially show up anywhere in the system. Now you can enjoy the road with that DOHC.

[pocket-rocket]

There are few things harder to fix on a car than a wiring job done by someone else.At least with hard parts it is pretty easy to find what is wrong and repair or replace.

QFT!