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Have a bad misfire any ideas?

(1990 Ford Ranger)
in Elkhorn, WI on September 10, 2011
i have a 1990 ford ranger with 4.0 v-6 recently put in head gaskets and upper half gaskets, plugs, wires, fuel filter, checked fuel pressure at schrader valve and it stays between 30 and 40 psi. tried two different coil packs both used and problem continues. computer comes up code 41 which is for o2 sensor.
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on September 10, 2011
When you reinspect the plugs are they fouled? Did you test the O2 sensor? What is the compression of the cylinders since you put it back together? Did you have heads resurfaced and valve checked/done while apart?
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on September 10, 2011
have not pulled plugs back out, did not test o2 sensor, did not do compression check but cylinders had no ridge when it was apart, and just checked heads for flatness myself.
on September 10, 2011
Well then you have some work ahead of you. How did you check the head flatness? Did you have a machine shop check them? Sounds like you may have cut too many corners.

So you checked the compression when you just now pulled the plugs? What are the readings for each cylinder?

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We are saying "you are a dummy" because if you know what you say you are not sharing info in order. We do not have time for a shadetree who says he has all this knowledge but does things in way the wrong order as far as stating the problem and how you go about finding the problem. If you have torn down "lots" of engines then you should know to take to machine shop to verify head as a good unit. You are a shadetree and ask for help when you are too deep in crap. give us the correct info in the correct order and we will help. If not, then too bad.


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Why oh why do you people that ask for help not give us all the info in the first post. Now you tell us that it was running this way before you took the heads off. The way you post makes us think this all took place after you put it back together. You have wasted our time, your time and your money. The misfire should have been diagnosed before any teardown and address what is needed. Why do you people hide info? Why?
on September 10, 2011
it is not a matter of flatness i checked them with a flat level and a feeler guage and the compression is fine, i am checking the plugs now. this is not a compression issue, it was running like this before i took the heads apart. it is something to do with firing. and when the truck is going down the road under load it pops out the exhaust. misfiring like coil pack issues.
on September 11, 2011
I couldn't agree with you more raiderron. Edward41 should have stated the original problem long before he wasted all that money and our time. Now edward41 most likely has generated more problems than he had before.
on September 10, 2011
do compression test ckeck cracked plugs ckeck plug wires could be bad valve do valve job
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on September 13, 2011
to all of you that have tried to help. i appreciate the advice, but i am no rookie at this stuff, i have done many head jobs and know what i am doing and what i am looking for. i have no bad head or valves cause every cylinder has 180 lbs. of compression, i have spark to all 6 plugs at the head when i check them. why do you all act like you know what your talking about when to me your all talking in circles. i have done more engine tear downs than i can count and never put one back together wrong yet. so please don t speak to me like i am a dummy cause i am not.
on September 10, 2011
You have spent way to much money doing it yourself. You do not know what you are doing! You should have had a machine shop check the heads out. You most likely have a bad head/heads. This is way above your skill level. I know you do not want to hear this. OH WELL!
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