[ineeda5.0]

I bought a 5.0 foxbody this week, The only problem is the engine slightly misfires and there is a small leak by the header...... Probably not the brightest idea buying a car that misfires considerign my limited knowledge on mustangs, but what is the most common cause of misfiring on 5.0?

[ROCUN]

Start with a tune up. Plugs,plug wires,distributor cap. I would also chage the oil since its new to you.

[ineeda5.0]

oh forgot the mention the guy that i bought the car from, chanegd the distributor cap and rotor as well as spark plugs but not the wires, im jus hoping its not a compression loss

[ineeda5.0]

i t starts up and idles fine, but it splutters during acceleration

[kilog55]

plugs could be shot, could be bad fuel, bad timing or ignition system

[ITLRUN]

I know this is something you should have checked, before dishing out any money for the car. I know you mentioned that you don't know much about Mustangs. But don't you think you should have had someone, who does know Mustangs before you went to check it out. Misfireing could be a number of things, plugs not gapped right, timing off by a few degrees, bad wires, cracked cap or rotor and the list goes on. If your worried about compression loss, don't you think you should do a compression test. There should be no more then 8 to 10lbs. of compression difference between cylinders. If there is more then quoted, then just pull the motor and start fresh no sh*t. I know I would, I don't do anything halfass. Sometimes it's a hard lesson to learn, but learn from your mistakes and you'll do just fine. Even something as small as a vacuum leak can cause a misfire. So check all your hoses to make sure that there not dry and brittle, Mike. SCT Tuner. P.S. Good luck with it, Mike.

[ineeda5.0]

Originally Posted by ITLRUN

I know this is something you should have checked, before dishing out any money for the car. I know you mentioned that you don't know much about Mustangs. But don't you think you should have had someone, who does know Mustangs before you went to check it out. Misfireing could be a number of things, plugs not gapped right, timing off by a few degrees, bad wires, cracked cap or rotor and the list goes on. If your worried about compression loss, don't you think you should do a compression test. There should be no more then 8 to 10lbs. of compression difference between cylinders. If there is more then quoted, then just pull the motor and start fresh no sh*t. I know I would, I don't do anything halfass. Sometimes it's a hard lesson to learn, but learn from your mistakes and you'll do just fine. Even something as small as a vacuum leak can cause a misfire. So check all your hoses to make sure that there not dry and brittle, Mike. SCT Tuner. P.S. Good luck with it, Mike.

I did bring someone with me, my boss use to be a mechanic and he has a foxbody of his own, he checked the car for a good half hour and told me the potential problems, but he still recommended I get the car, Im trying to learn as much as i can.... I know its hard to know what could be causing misfiring and i apologize for my generlized question but i figuired there could be a common cause of misfiring on 5.0s that i do not know about... Thanks btw

[Blackbeauty90GT]

I would pull the plugs and look at them first your self to see what they look like if your air/fuel ratio is off it will foul up a set of plugs fast. Congrats on the new 5.0 I just got one this week too.

[NOSty Pony]

if the wires were not replaced, start there. just get a good set. Ford Racing makes good 9mm wires. or just go with the stock 8mm ford wires.

[foxrider7147]

i just got a 89 gt about 3 weeks ago drives great but when i was playing around be a A** making some smoke it a a back fire or 2 when drivin off..