Mustangmutt

Got my '90 GT running last week. 306 with Speed Pro Pistons, B303 cam, stock (for now) rockers, Shorty Headers, 2000 Navigator GTP heads with a little bowl blending and port work on the exhaust side. '97 Explorer intake with work done on the lower intake ports, 24 lb injectors with an adjustable fuel pressure regulator set at 30 psi. A 70mm EGR spacer, throttle body and mass air body with the original sensor, a cold air filter and an electric radiator fan. Stock ignition. The rear has 373 gears, but I might go back to the stock 308 gears.
It pulls easily to 6 grand and feels like it would keep pulling. I have not yet taken it to the track so I have only gone through first second and third gears at full throttle. I have a stock PCM. Timing is at 14 degrees. How important is it to have a mass air sensor that is calibrated to 70mm? Which chip if any should I consider? I want a good streetable car that I can take to the track on occasion. I installed all the smog set up even though the GTP heads are not equipped for air injection, I need to pass the visual test for inspection purposes.
I am also experiencing charging issues at idle when the electric fan kicks on or if I use the A/C. It has under drive pulleys. I have put a 95 amp alternator on and it helped, but does not cure the problem at idle. When the voltage drops below 11.5 the idle begins to surge.

mjr46

mass air is calibrated to injectors and it is important suffice to say.......and if you have underdrive pullies , remove them to cure low output at idle

AdderMk2

1: Your pressure should be set at 39PSI with the vac line disconnected.

2: Calibrated to 70mm? Im sure you mean Calibrated to 24#. Its very important in you don't get the car tuned. If you are going to get the car tuned, you should pick up a 94-95 70MM MAF (housing and sensor).

3: Get a dyno tune... nothing else will suffice.

4: For starters, you have UDP's.. so ofcourse you will have charging issues. second, you should be running a 130A alt. A 3g conversion would be a REALLY good idea.

Mustangmutt

Thanks.
I'm not sure a Dyno tune will work on a car that the PCM can't be recalibrated. It is an OBD I. I thought you can only chip them with a piggy back type of chip. I will re adjust the fuel pressure and see how that changes things. I think I found a 93 Cobra mass air set up, and from what I have read they have 24lb injectors and 70mm housing. I didn't know 94 / 95s ran 24lb injectors.
I had a .5 drop between the Batt post on the Alt and the Battery. I ran an 8ga wire directly from the Alt to the post on the Starter relay on the fender and it helped. So long as I dont sit idle for to long, but I will probably change the pulleys back to stock.

Mustangmutt

Oh and where can I pick up the 130 amp conversion. The Alternator I installed is a 3g from a 93 Aerostar 3.0L which is factory rated at 95 amps. Does someone make a kit to convert the alt to 130 amp, or do I have to buy the whole thing?

mjr46

you can't use the cobra maf and 24's together unless you also install the cobrA ECM, the calibration for the 24's is housed within the ecm not the cobra maf

AdderMk2

Im not even going to begin to describe the level of things that are wrong in your post.

for one.. I tune EEC-IV mustangs. your car CAN be dyno tuned.

also, get the parts that I told you to, not what you ASSume will work.

Mustangmutt

ADDER, who's program do you use to tune EEC IV? Or do you write your own. I have taken a 2000 GT, used a Diablo programmer and had it tuned on a Dyno. All done through the Diagnostic port. Maybe you can enlighten me on the process without beating me up. According to MJR46 the ECM is what is calibrated for 24lb injectors. If that is the case, what good will a 94/95 MAF do me? I already have a 70mm MAF housing with the original sensor. Right now the car runs pretty damn good.