I'm interested in a 93 4cyl coupe that has been converted to 5.0 using a stock 88GT motor with stock mass air sensor, 19lb. injectors, etc. The current owner has converted the engine to mass air, but somehow, which is hard to understand, he is using the speed density computer to run the car so he tells me. Anyhow, the engine billows black smoke when it runs and when the spark plugs are pulled raw gasleaks from the cylinders. He seems to think that installing a 93 engine harness and mass air computer will correct the problem. I don't understand how the car runs with the speed density computer. I have several questions; Do you think installing a mass air computer and engine harness will correct the problem? Could the problem be a bad fuel pressure regulator? If I do opt for the mass air computer and engine harness will any 89-93 harness work or does it has to be year specific, ie. 93for93, 92for92, etc.? Any suggestions.

Thanks

 

1. Definitely needs a Mass Air computer. Something like A9L. There is more to it than that see:

http://www.stangnet.com/tech/maf/massairconversion.html
It is a wonder the engine even starts when hot.

Speed density computers use look-up tables to determine fuel/air mixtures they won't measure accurately in a MAF system.

2. Bad fuel press reg? Could be.

3. '89-93 harness should work however be aware that somewhere along that range airbags were added and may be a complicating factor in the harness setup. Not sure. You should research.

Keep on.