Hi all from colorado! Not even sure where to begin with this but I will try and keep it as short as possible. 9 years ago my father aquired a gorgeous 86 fiero that had a 4.9l swap in it. It needed work but was solid. It kept having a misfire, being in AZ it was so damn hot to try and work on it. Well, my father was very ill at the time and ended up selling the car right before he died. Well, almost 10 years later I found the car forsale in Tennessee! My wife and I drove out there 2 days after finding it and we picked it up and brought it to Colorado. I now have the car back in my possession after almost 10 years. It was sitting in a barn for 6+ years in the same condition we had it way back then down to the dry craked and rotted tires we put on it in AZ. I put tires on it, plugs, wires. Cap, rotor, and new map sensor and she is about 90% running condition. Still has this intermittent misfire! I have heat sleeved damn near everything and all ends of the plug wires etc. Can anyone help me? Anyone recognize the car? Also, I cant get the fiero temp gauge to read and have replaced all sensors related (I think). Any One with 4.9l swaps I kindly ask if you could possibly help me get this family heirloom back on the road and if you have any advice please share! Thank you!![img]http:/ /images.fieroforum.com/userimages/Anthony0712/0620201805_HDR.jpg[/img][img]http://images.fierofor um.com/userimages/Anthony0712/0620201805b_HDR.jpg[/img]

Don't know if this will help. The HT series engines(4100, 4.5 and 4.9) used to have a problem with worn distributor gears. It would cause "ghost/random" misfires.
Some would be just worn and some would be cracked. Had had many not show slop at the rotor. Most had to pull the distributor to inspect. Now you have to remember this was back when we normally used an engine analyzer while watching the scope pattern for uneven firing time between cylinders.

Very nice car. Do you know who did the install? Please take a few pictures of the engine bay and post them. When you say misfire, is the engine backfiring, stumbling, or just sounds rough? Are there any code you can read with a code reader?

Jack

I don't know who did the swap, it looks like a clean install minus a few things here and there.