93 Ford Probe GT misfire under load (3500+ rpm)

[ViridDigits]

So I have a misfire happening on my GT it kicks around 4000 rpm generally. Ironically I just fixed a misfire that was happening at idle (new plugs and wires), went away, no problems for a couple weeks. My homeboy took my car to the car wash and washed it and on his way back it started this new misfire problem. I'm not sure what it could be. I have ideas, maybe the distributor, or fuel pump. My vacuum lines seem ok. Idk what to do, looking for tips or ideas. Maybe just better details for what I should be looking for with any of those as well as anything else. There's a cold air intake mod I installed a while back. Also the car sat with broken windows for about a year and a half, and a cut ignition wire under the steering wheel. Was running fine for about a month and half once it was again.

 

[GSCJR]

 

[AZjeff]

Cold air intake mod + car wash by homie immediately before misfire starts sounds like a starting point. Did he roll the windows up?

 

[ViridDigits]

Cold air intake mod + car wash by homie immediately before misfire starts sounds like a starting point. Did he roll the windows up?

I'm sure he did, not sure what the windows would have to do with it. I was thinking it could be part of the problem, if water got in. But I dont think there was a way for it to get water in with the engine bay closed. If it was water tho what would I do to fix that? Wait it out til the water hopefully evaporates?

 

[wolfox03SS]

It may be coincidental. A higher engine speed misfire when accelerating on a highway ramp or passing can almost always be simply tracked down to a dirty fuel filter. Change that out if it's in an accessible place. It's the cheap fix.

If after you still experience the engine stumbling under heavier acceleration? Check fuel pressure. Rent or borrow a fuel pressure gage. If out of spec after a filter swap, suspect in order of expense and expertise:

Check/test fuel pressure regulator and while you have fuel pressure gage, leakage test the fuel rail pressure after key on, no start... watch how fast pressure drops off. Then suspect and change fuel pump if pressure is weak and out of spec on the regulator check.

If you find fuel pump weak? Always install a new fuel pump and strainer sock (if equipped) along with an oem fuel regulator and a filter. Drop in a can of SI-1 or Berryman's B-12 afterwards for an injector cleanup afterwards on a near empty tank and refuel and drive her nearly out of gas after treatment before refueling again.

Good luck!

 

[Trav]

Typical symptoms of a weak ignition coil (not the only possibility).

 

[CBR.worm]

Bad or misinstsalled new wires?

 

[grjr]

this thing has a distributor? check the cap and rotor for any cracks or signs of arcing. check the easy stuff first!

 

[Aichiguy]

Was there any oil in the spark plug tubes?