This is topic HELP! Missfire killing me... in forum Tech Talk at Northern California Ford Owners  .


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Posted by MistaFosta (Member # 4068) on :
 
First off, this is a 90 LX 5.0 (Ex CHP) It has a mac cold air, and a set of underdrive pulleys, otherwise it is stock.

A little while ago, I developed a strange missfire over 3000+ rpms under full or almost full throttle. It acts pretty much like a rev limiter, causing a complete loss of power (Can't even get past 3200 rpms). It only does it once the car warms up, and only under heavy throttle above 3000 rpms. Otherwise the car runs absolutely perfect.

I have either swapped with known good, or replaced these parts. Distributor, module, coil, plugs, wires, cap, rotor, fuel filter, fuel pump, MAF, intake air temp sensor, water temp sensor, put the stock intake piping back on, TPS, and I checked all my grounds. Also tried another computer. I gapped the plugs at 50 and 45, no difference.

If anyone has ANY suggestions, please let me know. This car is really pissing me off..
 

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Posted by nitrous_bob (Member # 77) on :
 
hook up a fp guage to rule that out for sure...
watch the fp when it starts to stumble.

if it's good...gotta be spark.
 

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Posted by FasterDamnit (Member # 442) on :
 
Codes?
 

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Posted by MistaFosta (Member # 4068) on :
 
It has a EGR code, but it throws that when it is cold, and has done that for about 6 months now...
 

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Posted by PunkINa5.SLOW (Member # 10) on :
 
How did swapping out the cheap ass plug wires you have on that thing work for you?
 

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Posted by PunkINa5.SLOW (Member # 10) on :
 
oh my bad I see that you swapped out the plug wires.


Tell you what hook that MSD box up and see if it makes any difference just for GP
 

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Posted by PunkINa5.SLOW (Member # 10) on :
 
awww screw it come back over in the morning and Ill actually go for a ride in it with you this time to try to help you isolate
 

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Posted by six 5.0 (Member # 3153) on :
 
I have an 86, It does the same the shit mine does it when it's cold. It fuccin pisses me off, I can not figure it out either. I have had suggestions to change my cats and my mufflers (stock). Maybe you yau should look in to doing the same, if thier stock.

good luck
 

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Posted by MistaFosta (Member # 4068) on :
 

quote:

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Originally posted by PunkINa5.SLOW:
awww screw it come back over in the morning and Ill actually go for a ride in it with you this time to try to help you isolate

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quote:

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Originally posted by DaveG:
With a DVOM, sweep the TPS and look for a bad spot. I'd double check for a TPS code.

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quote:

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Originally posted by PunkINa5.SLOW:
I think somehow you did something wrong when you put the fuel pump in just my .02

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quote:

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Originally posted by forced331:
If you have an aftermarket ignition, that would cause the problem your dealing when an igition is bad.

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