Hi folks,
I've had my car less than 1 year, and I'm still working out some bugs. Earlier this year I had misfiring under boost (moderate boost). Replaced the plugs with Motorcraft double platinums, and I thought it was running very well after that. During this summer I notice that under full boost, when the engine is hot, from 4-5 krpm I get some type of subtle misfire, or stumble or interuption of power. It is not as clear as typical "bad plugs" type misfire on these cars. When the engine is cold, I do not notice any lag/misfire. The car will pin my stock boost gauge in this rpm range, I presume this means the car is making 15 psi or more boost.
The car has many bolt-ons (almost all of them I think), large MAF, FMIC, MPX blower, mid length headers, MP inlet, pulleys, high flow cats, 2.5 exhuast etc.....I was told the injectors are upsized, but I don't know to what. I was told the motor was built 4K miles ago - but have no data sheets. I do not know if the fuel pump has been upgraded to be appropriate for the modifications yet. I don't think it has any chip/tune. By the way, how does one figure out if it has a chip/tune? Is ther an obvous way to determine the fuel injector rating?
So anyway, this past week I bought autolite APP103 plugs, gapped them to 0.035 inch, and still the engine response is the same. I do not think it is a plug issue. The plug wires are the big blue live wire models. They appear in excellent condition, and I checked the fit on the plugs a few times.
I have a friend who owns a speed/tuning shop, and I plan to take it them to have them tune the car, and use their dyno. But thought I would see if anyone has any other advice, or has experienced very similar problems. Hard for me to imagine that the motor would run perfect with all of the bolt on parts but with no tuning done - anyone agree?
I've had my car less than 1 year, and I'm still working out some bugs. Earlier this year I had misfiring under boost (moderate boost). Replaced the plugs with Motorcraft double platinums, and I thought it was running very well after that. During this summer I notice that under full boost, when the engine is hot, from 4-5 krpm I get some type of subtle misfire, or stumble or interuption of power. It is not as clear as typical "bad plugs" type misfire on these cars. When the engine is cold, I do not notice any lag/misfire. The car will pin my stock boost gauge in this rpm range, I presume this means the car is making 15 psi or more boost.
The car has many bolt-ons (almost all of them I think), large MAF, FMIC, MPX blower, mid length headers, MP inlet, pulleys, high flow cats, 2.5 exhuast etc.....I was told the injectors are upsized, but I don't know to what. I was told the motor was built 4K miles ago - but have no data sheets. I do not know if the fuel pump has been upgraded to be appropriate for the modifications yet. I don't think it has any chip/tune. By the way, how does one figure out if it has a chip/tune? Is ther an obvous way to determine the fuel injector rating?
So anyway, this past week I bought autolite APP103 plugs, gapped them to 0.035 inch, and still the engine response is the same. I do not think it is a plug issue. The plug wires are the big blue live wire models. They appear in excellent condition, and I checked the fit on the plugs a few times.
I have a friend who owns a speed/tuning shop, and I plan to take it them to have them tune the car, and use their dyno. But thought I would see if anyone has any other advice, or has experienced very similar problems. Hard for me to imagine that the motor would run perfect with all of the bolt on parts but with no tuning done - anyone agree?