I need help coil problems

[tdogsmvp]

I swaped my speed density computer to a Mass Air, I switched to everything the ECU and wiring harness and now I can't get my coil to fire! Please someone help me I got to get the mustang back on the road.

 

[88mouse]

What year is your car, and what year is the wiring harness?

 

[tdogsmvp]

It is was a 91 coupe 4 cyl and now it has a 5.0 in it, the computer come out of a 90 5.0 auto

 

[88mouse]

the computer will work. Did you use the 90 engine harness? If so you will have to find a 91-93 engine harness.

 

[tdogsmvp]

i used the computer and harness out of the 90, why wouldn't it work?

 

[88mouse]

87-89 are interchangeable,91-93 are interchangeable, and 90 is a year all by its self.

 

[HISSIN50]

What aspect are you missing? Do you have VPWR to the coil? Or is the ground signal from the TFI missing?

 

[tdogsmvp]

so because the car is a 91 I have to have a 91 harness, but the car was a four cyl. the reason for the mass air change is I have double titanium valve springs, E cam, moded E7 heads 1 3/4 longtubes 3inch exhaust, double roller timing chain, smog is blocked off, mac cold air intake. And the car wouldnt stay at a idle with the speed density computer and I read in another thread that the speed density couldnt keep up with the cam. I don't know you tell me!

 

[tdogsmvp]

I just ain't getting any fire from the coil, I have a msd blaster coil high tower, and when I wire it up both sides of the coil are hot , and the coil want fire .

 

[HISSIN50]

In able for this to work effectively, one has to be able to provide diagnostic results.

If you put a test light across the terminals at the coil's electrical connector and crank the engine, does the test light flash? If you ground the test light and probe the positive electrical wire to the coil (with the key on), does the test light illuminate?

 

[tdogsmvp]

yes the with the key on the test light does light up , but the positive and the negative lights up, its geting power to the coil but the coil want fire i can't figure this out. and it worked on the speed density computer it would cank right up but the mass air stuff is giving me some problems

 

[HISSIN50]

yes the with the key on the test light does light up , but the positive and the negative lights up, its geting power to the coil but the coil want fire i can't figure this out. and it worked on the speed density computer it would cank right up but the mass air stuff is giving me some problems

I'm not sure what you're saying.

If your hypothesis is correct however, you need a new coil.