I thinking of buying a car from this guy it used to have a 305 and that blew up
so he put a 350 engine in it and it has some kind of computer problem its a
fuel injected engine I think he used the old parts from the 305.It runs and starts but has just a little bit of a running problem it sounds like it needs to be timed to me. Its a good buy if I can get it to run good, it only has 12000 miles on the bfgoodrich engine. Thanks for any help.

 

I think you mean GM Goodwrench engine. That was a good quality replacement motor. I would suggest you invest in a thorough diagnosis before you buy any parts for the car. Don't assume because it's a computer controlled vehicle with runability issues that is needs a computer. The ECMs rarely fail. It's much more likely a sensor, electrical or mechanical issue.

Generally I would say if the car starts, has good oil pressure and no engine noise, it's probably a good buy. Diagnosing it may take some work or you may be better off using a trustworthy and knowlegable mechanic. If you can't drive it, atleast pull the trans dipstick to check for burned or contaminated transmission fluid. Also, look underneath for leaks.

 

If he just put the 305 parts on a 350 that would cause problems... for example the injectors are differant sizes and the chip BCC are differant, not sure if the knock sensors are the same...

 

The car is going to come home this weekend ,he told after he played with the timing to advance it, the ECM lights on the dash started flashing like crazy after that. I'm going to take it to a friend with a timing light first. The computer
on it is for a 350 and the injector is for a 350 the transmission checks out new. Thanks for your help worst case I put another manifold on it with a carb, and smoke some tires.

 

All i can say is if you want to run EFI, you need to do your homework. You can learn alot here but most of us who are really into these cars have worked on them to a fair extent and have studied their systems so that we are able to diagnose, repair and modify them to suit us. The factory service manual is a great resource for information.

 

When the swap was done the prom should have been replaced with one for a 350 and the EST for a 350.
The knock sensor should be the same but a good way to research the things are to look up part numbers for both items.
Go to some site like autozone.com and look up the part number for a 305 TBI and compare it to a 350 TBIs' part number for any items in question.
But I do know for a fact from doing these swaps that you need the prom and EST for a 350.

 

IVE SEEN THINGS LIKE THIS COME DOWN TO A BAD GROUND OR A BAD SENSOR PLUG(s). I ALWAYS SPRAY DOWN ALL THE PLUGS WITH ELECTRONICS PARTS CLEANER WHEN I GET A NEW ( NEW TO ME ANYWAY ) IROC-Z. DONT RULE OUT THE OBVIOUS STUFF.... FUEL FILTER, ECM GROUND, ENG GROUND, COIL, IGN MODULE, EGR, VACUUM LEAK, TUNE UP ETC...

 

tranny needs to match as well(manual.auto)