Backfire, big loss of power after 60

[Fayt]

K, round 17 for problems with my car.

I have the same mods in my profile, but I'll list them here. Evo 3gt w/ported exh mani, 3" turbo back exhaust w/no cat, greddy IC piping, Injen intake, 1st gen motor, STOCK boost, STOCK fuel pump, STOCK o2 housing. I finally got it running and boosting (thank god ) but there are minor problems that irritate me.

First, it'll backfire if I give it too much boost. Plugs are new NGK6ES's or w/e the model is. I know they are the 6's though. Coilpack is a 1st gen one, but myl spark plug wires are from the 1st gen motor when it was pulled from the car, whenever many years ago that was. I also think it could be my fuel pump, because of the airflow the evo has it could be cutting out or something. I have a 190 sitting around, but I've been doing other fixes so time hasn't allowed me at it.

2nd, when I'm on the highway, I'll be cruising and suddenly I will feel a weird vibration kinda like a muffled bzzzzzzzzt sound when I give it gas. It'll lose a LOT of power too, and no longer boost. But, if I put my clutch in and then let it back out it'll go away sometimes. Or if I put it into neutral and rev it a couple times it'll make the sound then clear up. Any idea what it could be? It *might* be my minor exhaust leak I have, but I didn't think it would cause that much of a problem. There are 2 tiny boost leaks I'm fixing soon, one at the TB elbow gasket, then my TB shaft seals are leaking too, thats it. It only happens when I'm above 60 though. Any ideas?

 

[WillyC]

Fix your KNOWN boost leaks and then see if that fixes the problem. That is most likely what it is. Although if you're running more than 14-15lbs with that EVO3 and no fuel pump upgrade you're asking for trouble. As for the buzzing sound, get under the car and see if the exhaust is rattling around.

 

[sepulchral]

i have a eclipse with evo 3 motor and it has the same ####in problem i think it has to do with the cas and cam angle sensor

 

[Fayt]

New seals came in today and going in tomorrow, along with my new TB elbow gasket. Also, I'm gonna tighten the shit outta the two O2 housing bolts to fix my exhaust leak and *hope* that's it.

I'll keep you guys updated, thanks.

Oh yea.... any way it could be old spark plug wires? They are old, the plastic is rotting and I have no idea how many miles are on them. I'll see if I can get some new ones.

 

[T9S1i]

The insulation in the spark plug wires is KEY! if you have damaged wires then they NEED replacement. Check your wires for little white spots on them, this could indicate that the charge is arcing to the motor where you dont want it to. If i were you id definately replace the wires ASAP along with getting all other maintainence done before boosting over stock or running the car hard at all.