Is there a common misfire?

[Photonfanatic]

I was hoping someone here could tell me if the 1994 GT had a common factory defect that would cause an engine miss. My old red 1994 GT had it, and now my new 94 GT has it. I can't seem to locate the problem. It doesn't seem to be in the ignition system anywhere. I have a fresh tune up in there so that isn't it. Got new plugs, wires, distributor cap and rotor, O2 sensors, air filter, fuel filter. And as far as I can tell, there aren't any vacuum leaks anywhere. I swear I must have been over that whole vacuum system by now.

The miss isn't real bad, but you can tell its there when you're sitting at a stoplight or something. And yes it is when the car is at normal operating temperature. So... maybe a bad injector? Did these cars have problems with injectors going bad or anything like that?

 

[330CubeGt]

Orig. Coil?

 

[Photonfanatic]

No idea. I have another coil I could try, but it too is used. Guess there is no harm in trying since I don't have to pay anything to do it.

Side question: Are there really any better coils out there for that particular car? I seem to remember MSD sells a red one, but it looks exactly like the factory one. Only difference is the color.

 

[JoshHooten]

clogged fuel filter?

 

[GT Rob]

That's funny my car is doing the some thing I have a new coil that is 3 mouth old

 

[Photonfanatic]

Changed the fuel filter already. As much as I've been over all the possible causes, I'm really leaning towards it being a crappy injector. How hard are they to change out? I try to do all my own work but this one may be one that I take to an ASE certified mechanic.

 

[rz5.0]

Injectors are ez to change remove upper intake.. Unbolt fuel rails(2 bolts on each one) pick straight up... Swap inj push fuelrails back down make sure its all the way down bolt back up... Bolt upper back down.. Bleed fuel pressure first!!!!!!!

 

[JoshHooten]

Injectors are ez to change remove upper intake.. Unbolt fuel rails(2 bolts on each one) pick straight up... Swap inj push fuelrails back down make sure its all the way down bolt back up... Bolt upper back down.. Bleed fuel pressure first!!!!!!!

YES make sure they are all the way in. when I changed my intake I didn't get one injector all the way in and it started to spray gas on the intake.
unplug your fuel pump first ,crank the car and let it run out of gas so there is no fuel in the rails.

 

[rz5.0]

If you do change inj.. You might as well make the junp to 24's or 30's...

 

[JoshHooten]

If you do change inj.. You might as well make the junp to 24's or 30's...

That's very true I wish I had done that when I had my intake off

 

[Photonfanatic]

Yeah I was thinking the same thing. But my motor is pretty much bone stock. So if I upgraded to the 24's, would I still be able to get the gas mileage that a bone stock motor gets? Or no? The computer controls it so maybe they only spray what is needed?

I know you don't need them on a bone stock motor but... I do plan on doing the typical heads/cam/intake one day.

 

[rz5.0]

You would need a tune or "calibrated MAF" to run 24 or 30's mpgs should stay close to the same.

 

[Raffaelli]

Do a compression test. Then do it again with a few squirts of oil in the chamber. That'll let you know if the motor can even run smoothly.

I bet your fuel injectors are not spraying 100% even over the set. There are places that will rebuild them and flowtest em. I highly suggest you keep em the factory 19lbers.

 

[rz5.0]

Do a compression test. Then do it again with a few squirts of oil in the chamber. That'll let you know if the motor can even run smoothly.

I bet your fuel injectors are not spraying 100% even over the set. There are places that will rebuild them and flowtest em. I highly suggest you keep em the factory 19lbers.

I would agree on the inj if he was going to stay stock but once he starts to changing things.. They will need to be replace.. No point in spending money twice..

 

[Photonfanatic]

Would it be beneficial to buy a "balanced" set of injectors? They sell some that have all been matched up according to how much they flow. Seems like this would make an engine run a lot smoother.