BREAKING UP AT HIGH RPM ???

howiefisher · Jun 3, 2008

well the new motor is in and running good but i gave it a good shot today and at around 4000rpm and up its breaking up so i swaped the coil no change ckeked timing base timing is at 12 ?????really anoying considering its a brand new motor ?had the same prob last year but coil fixed it ??could it be the pick up coil ???are they a bitch to change ?also i have 24lb injectors with calabrated mass air , BUT STOCK HEADS could this be my prob to much fuel it runs great just not in high rpm???what to test ??guys

howiefisher · Jun 3, 2008

could the TFI modual mounted on the pass fender cause breaking up at high rpm??

earleys94gt · Jun 3, 2008

Are your plugs gapped correctly?

Is the fuel pressure at the correct PSI?

howiefisher · Jun 3, 2008

what should i gap them at .40 fuel pressure is stock setting but has 24lb injectors should i take them out and put the 19 lb back in

Chythar · Jun 4, 2008

Running rich shouldn't cause this problem. However, the stock spark plug gap is .054. If your ignition system is stock or close to stock, you should stick with the stock spark plug gap. With such a small gap, the fuel isn't burning as fast so it would make sense you're having trouble at higher RPM's. Re-gap your plugs at .054 and let us know what happens.

Redsnk95 · Jun 4, 2008

Check the fuel filter and TFI module.

howiefisher · Jun 4, 2008

well i havent gaped them yet but i will tomarrow and i am going to change the fuel filter to but how do i ckeck the tfi module under the intake ??

HISSIN50 · Jun 4, 2008

You don't have platinum plugs in there by chance? They don't conduct as well as copper (OEM material) and can cause higher RPM missing.

Check the wire routing to be sure you dont get a crossfire situation (there was a TSB about this on Foxes but I'm not sure about it for our cars).

Lastly, as the guys suggested, be sure you're not losing fuel (it's easy to get tunnel vision and concentrate on the ignition). I'd never stick a diagnostic gauge under the windshield wiper while going for a drive on a closed course [with a passenger to watch the gauge]...........

howiefisher · Jun 5, 2008

yeah hissen they are platem plugs and the wires are for a fox there to long should i change the plugs and wires also how could i test the tfi they cant seem to find the tfi module at parts stors just a ignition module but the pic does not look like mine .mine has cooling fins on it and its mounted on pass strut tower under intake ??is it a dealer part only ??

Chythar · Jun 5, 2008

To replace the TFI, you have to remove it from the heat sink (the fins you see). Unless you have a 7/32 deep socket, you'll have to buy the specialty tool. Some stores have it as a "Ford Ignition Tool" or a "Ford TFI Tool". I bought mine from Summit: Ford Ignition Module Tool.

The spark plug wires should be fine, the same wires work for 86-95 5.0 engines. Not sure how to test the tfi, sorry.

HISSIN50 · Jun 5, 2008

I'd get copper plugs in there - the car will run better anyhow (even if that's not your exact issue). Plat plugs have been known to cause a miss at 4K+ RPM.

The TFI is mounted to a removable heat sink.

howiefisher · Jun 5, 2008

well that makes sense then so the module is in side the fines that i see,like a cover ???ok well i have a 7/32 socket and a 5.5 mm so i dont need the tool thanks guys ?so i am going to change the plugs any way and wires ,cap and rotor ,and if still does breaks up ll change the tfi module so the module will just slide out of the cover after i take out the bolt /nut right

Chythar · Jun 5, 2008

You are correct. Once the two bolts are removed the tfi slides off the heat sink.

howiefisher · Jun 5, 2008

cool thanks chythar so if i change pluges and wires and it does break up you think that a tfi module will cause break up at high rpm ??? or you know they would ?

my500hp99gt · Jun 5, 2008

You said you had stock heads? Are they the original heads? Faulty valve springs can cause break up in high rpms...

Also, related to the plugs platinum plugs electrode does nto dissipate heat very well and will turn into a glow plug and can cause detintation issues when shooting nitrous, even on a small shot.

Your type of problem is unfortuneately one those things that you just have to trial and error it. You test one theory, if it doesnt correct it, move on to the next most logical.

Good Luck.

Greg

howiefisher · Jun 8, 2008

well i put in new copper plugs and new taylor wires,msd cap and rotor and still breaking up at 4000 rpm and up so i guess i shoud try and change the ignition module ????is ther any thing else that would cause this besides my fuel pressure droping off >>it has 24lb injectors with summit racing mass air calabrated for the inj,but i have stock fuel pump ????what do you guys think ?go back to 19 lb or try the ignition module first ?>

BREAKING UP AT HIGH RPM ???

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