jporter.s281gt

I purchased a 2003 GT that used to be an automatic but at some point in its life had a 5 speed manual put in and it has caused a few issues (speedo calibration, fuel pressure etc.) what is the best way to fix these issues and get the car running the way it should w/o going back to an auto?

dawson1112

Not sure how a manual trans swap can cause fuel pressure issues. As far as the speedo is concerned it depends on what manual trans was swapped into the car. If its an older t-45 from 96-98 they have a gear and the 99+ transmissions use a magnetic pick up. So if its an older t 45 it may not even register speed at all which can cause some drivability issues , mainly with how the car idles while coasting.

Could you possibly describe the problems your having exactly? I don't think that its transmission related.

jporter.s281gt

The car lot i bought the car from didn't know of the swap so they assumed it was the fuel pump going out so i got a good deal on the car but when i got it the speedometer is way off it says 70 when you're doing 35 and 135 at 70 etc. i took it to have the speedo recalibrated and to fix the loss of fuel pressure at full throttle thats how i found out it was originally an auto, because it was giving codes for an auto. the car has power like it should in 1st and 2nd but falls on its face in 3rd half way through the rev range i've replaced injectors coils and plugs i've atempted to get a new ecu but the parts won't sell me one without the vin# but i'm assuming since the car was originally an automatic that would't solve anything

jporter.s281gt

the only other thing i could think that would cause problems would be the 4.10 gear it has but i don't think that would make the speedo act up like it does

dawson1112

In deed 410 gears wont affect it that drastically. They may through it off by 15 -20 or so. Recalibrating the speedo is not that difficult, simply purchase a dallas mustang speedcal unit and set it up so the speed is reading correct. Done using some switches inside the speed cal box , but you need some way to track actual mileage for 10 miles and then compare it to the mileage that the trip counter says you traveled. I can go more into that if you want later.

Since you have some codes could you post them up so we can see what the PCM is actually telling you is wrong?

jporter.s281gt

Yeah it will be monday before i can do that though

dawson1112

Have you shut off the traction control and see if it does better as far as missing is concerned? I just thought about it considering your running 4.10 gears maybe its hitting third and spinning a bit so the traction control kicks in.

BlindGUYnAR

If you really want an ECU then search google for the same car year, make, model, etc with a manual trans. Vin#'s are a dime a dozen. Use it to order the part.

mustangman02232

If your getting auto codes it still had a auto computer in it, try swapping in the computer out of a 01.5-04

jporter.s281gt

Snagged an ecu from a wrecked 04 and thanks to a local tuning shop it runs awesome!