97 gt missfire problem

tri5333 · Mar 8, 2009

my 97 gt has a missfire at 4000rpm under heavy acceleration sounds like a popping sound. Mods are c&l cold air, c&l intake elbow other than that it is stock. The car has 61k miles and the plug wires were replaced by the previous owner with belden 8mm wires. The cel has not activated once and the car passed e-check no problem. Any ideas or suggestions would be appreciated.

schoffs4 · Mar 8, 2009

It would be so nice if ford had misfire counters huh . How does it idle? if it idles with no misfire i would check for possible cracked valve spring if its poping sound your hearing.

mrvax · Mar 8, 2009

Probably 90% of misfires are spark plug & wires related. I had some top of the line Rousch wire one time that only lasted 2 years!

If you can do your own plugs, buy a new set, check the gap & use a torque wrench to set them. If that doesn't fix it, change out the wires.

COramprat · Mar 8, 2009

Is there any hesitation? If not then you may have detonation issues. A consistent misfire usually throws a code.

bhuff30 · Mar 8, 2009

A bit of a long shot, and definately consider the plugs and wires first... but you could try cleaning the wire in the mass air meter. It may be so lean at 4000rpm that it starts missing. Certainly, a pop is not normally found with an ignition miss.

NO BRAKES · Mar 8, 2009

im not sure about mod motor c&l maf's but ive not had any luck with em on push rod motors. maybe thats your problem.

schoffs4 · Mar 8, 2009

Im saying possible valve spring because of his 4000k miss. Usually a plug or wire [usually the cause of a miss] will miss regardless of rpm or load. I found in the past with a overhead cam 4.0 with same issue miss under load the valve will float at high rpm because it cant fully close tight because of the spring cracked but run ok at lower rpm. Just something to look into. Your popping noise is what makes me think this. Good luck

mrvax · Mar 9, 2009

schoffs4 said:
Im saying possible valve spring because of his 4000k miss. Usually a plug or wire [usually the cause of a miss] will miss regardless of rpm or load. I found in the past with a overhead cam 4.0 with same issue miss under load the valve will float at high rpm because it cant fully close tight because of the spring cracked but run ok at lower rpm. Just something to look into. Your popping noise is what makes me think this. Good luck

schoffs, whenever I've had a miss due to plugs/wires it seems to only happen under load, at higher rpms. If you take it real easy, you don't hear it. When you nail it, that's when the problem seems to occur.

Just my 2 cents.

Off topic: When are we supposed to replace the coil packs on our 4.6L ?I have 104k and they seem to be fine.

COramprat · Mar 9, 2009

mrvax said:
Off topic: When are we supposed to replace the coil packs on our 4.6L ?I have 104k and they seem to be fine.

I wouldn't replace them unless you were having issues.

tri5333 · Mar 9, 2009

I just got back from driving it in the rain and it is actually worse. I dont want to randomly start changing stuff anyone with some suggestions?

mrvax · Mar 9, 2009

tri5333 said:
I just got back from driving it in the rain and it is actually worse. I dont want to randomly start changing stuff anyone with some suggestions?

Spark plugs are cheap. Try them 1st.

tri5333 · Mar 10, 2009

problem solved

Just installed ford motorsport fms-12259-r462 wires nothing else and it solved the missfire car runs better than it did before.Hopefully helps someone with similar problem.

tbird187 · Mar 14, 2009

I had the same problem today.. tried plugs first and it ran worse.... got new wires. and runs like a new car my wires were pretty new too

97 gt missfire problem

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