[kshel699]

I just installed a 94 mustang 5.0 auto computer (U4P0) in my 86 mustang, and it doesn't quite run properly. When cold it will stumble if given more than about 1/4 throttle and when hot it just doesn't appear to have the power it had before. My 86 has a 5-speed. Has anyone else done this swap, and if so, did you experience any of these problems? Also, The MAF sensor is out of a 3.8L thunderbird (I have a 90 mustang 5.0 stock MAF coming) Any advice would be helpful.

[AndrewRambo]

It is very important that the mass air sensor is matched to your fuel injectors and is for a 5.0. The stock injectors should be 19lbs so a stock mass air from a 5.0 will match. Also make sure that the MAP sensor vacuum port is NOT connected to the manifold vacuum. It should be open to air. Don't forget to plug the vacuum line that goes to the manifold!

[mylittleponie]

did you convert everything to mass air??? if so let me what all you did and i can give ya a hand...

[kshel699]

5.0 Mass air sensor came in today, but will not be able to install it until tomorrow after work. The 94 mustangs did not use barometric pressure, so the MAP sensor is completely eliminated. I did do a complete conversion to mass air, only I used a 94 computer vive an A9L or A9P. My computer is a U4P0. I have a cold air intake on it right now however the rest of the engine is stock.

[EagleAutosports]

That computer is one of the most tempermental ones to get, I bet it needs a tuned chip.

[kshel699]

I installed the 5.0 MAF sensor today and now it runs great (better than the 86 computer). Now I am going to adjust the TPS and do a tune up and I think it will be perfect. It is amazing how much difference there is between a 3.8 and 5.0 MAF sensor.