well i changed the wires and the plugs and it seems im still missing in the 4500+ rpms...can anyone help me??PLEASE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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Might be a cracked opti cap causing spark bleed. Could also be a loose rotor button cause the screws are backing out. Spray some water mist on all the plug wires and the opti and look for arcing. Check you plug gaps, should be .050".

 

bump. bump. bump

 

What all have you done to it? Need more info!

 

sounds like an opti problem to me get a new one and check if your coil pack is in good condition. my friend had the same problem and changed both of them and it was fixed.

 

I had a P0300 misfire code for a long time.

I replaced plug wires 3x(everything "looked" good), no arcing, seemed okay- result: no change

Replaced the coil: more power, still missing though.

I took a look at my opti harness, it was fried under the looms and the weatherpack connectors just feel apart. Put a new harness on, ran okay for a bit, then missfiring again.

pulled my opti off, it's toast. New GM replacement going on.

 

Sounds like the Opti or the Opti harness. When my 94 did this though, it was telling me that my fuel pump was on it's way out.

 

ok i checked my opti harness all the wires looked great...however, when i pulled the opti end out it had di-electric grease all over it. and then on top of that when i un plugged the MAP sensor it didnt run any different...i figure thats why my car idles rough....other than that the car runs great...even through 1st gear..hell i have 2.0 60' times. and then when it gets into second and gets up there in rpms it misses, im just starting to wonder if its somekind of an injector prob. the car has new wires, new plugs, 8,000 mile old fuel filter, new fuel press. reg., new cap and button, new water pump, and the fuel pressure is great...it was tested at all points except WOT. what baffles me even more is it only does it at WOT from a very slow roll or a dig. if i go to pass someone or just kick down on it, it wont miss.... also i do believe that this is the original opti at 104,000, also do you think i could have some failing injectors?? also when hooked up to a wideband o2 sensor...the a/f ratio was great untill about 3000-3500 and then it goes rich......and then its starts to miss after about 4500

 

You have the dreaded high RPM miss. My friend's Fleetwood is going through the same thing. We cannot figure it out. He's had a complete tune up, fuel pressure and everything is fine. Could be Opti...104k miles.

 

bumpity bump