Need some ideas about engine "miss"......

still chasing intermittant misfire under boost....checked plugs,they were installed in May when I r/r hgs,no apparent problems.....changed wires(ford oem],missfire stopped for about a week but then returned.....only codes were for o2,r/r both[that's another story].....replaced DIS,no change.....swapped out coilpack,misfire got worse.....went back to original coilpack.Car idles fine and runs great as long as I stay out of boost....could this possibly be a fuel pressure/fuel pump/ filter problem?Need some ideas,anybody got suggestions?
z

you could try a fuel filter, they arent that expensive. you should buy a fuel pressure guage and see what kind of pressure you are running at. stock is around 40 ish 38 - 42 or something like that so i have heard. and for every lb of pressure added (PSI) there should be 1 lb of fuel added, and if you arent getting this, it might be the fuel pump telling you something, or early stages of a poopy filter. could be a cam or crank sensor perhaps too, those are what looks to be the last of the ignition system that you need to replace...i went through all of em myself on my 91. but check the fuel pressure

I would go over the plug wires again and make absolutley sure that they are all connected and connected really well...I fought this once and ruled out the wires since I had just put new ones on and well...They were not on good enough apparently...May not be the case for you...But I would look again REAL CLOSE...


Brad

miss under boost

while you're at it, might want to check the spark plugs for carbon build up and proper gap and type (heat range).
bill

z90sc said:

.....swapped out coilpack,misfire got worse.....went back to original coilpack.......suggestions?............

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Just a suggestion, but could you have a short in the wiring harness going to the coil pack? Seems as when you fooled with it it got worse, then fooled with it again it got better. Maybe try wiggling the electricl connector/harness going to coil pack..or throw a ohm meter on it and check while bending it.....just a suggestion.

I had a miss once in my SC.took me about 8 month to find.It would miss at start up untill the motor got warm then would run just fine.And under boost it would miss warm or a cold .

It was a seaping head gasket,not a blown head gasket .but would leak only when cold or under boost.

RANDY