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misfire after installing new cap and rotor

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Old 01-16-2012, 05:49 PM
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Originally Posted by chris*tx
does the misfire happen all the time? during regular acceleration too?

Seems like things were just fine before you replaced the cap and rotor -- I wouldn't dig too deep until you figure out the rotor and cap are ok.

IIRC when I replaced my rotor and cap on my 5.9L I also changed a simple and cheap sensor below the rotor - that came recommended from this forum - maybe a crank position sensor?? Hopefully someone else can chime in.
Cam position sensor under the cap. No real need to change it, unless it is causing a problem. I would still verify the firing order on the cap...... I have been doing this for decades, and can still screw it up.
 
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Old 01-16-2012, 05:57 PM
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I have replaced the cap again and still not any better. Also checked plug wires and they all ohm out ok. Seems to me to be some type of ignition problem. Plugs and coil may be my next move.
 
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Old 01-16-2012, 05:58 PM
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Did it have the miss before you changed the cap?
 
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Old 01-16-2012, 06:06 PM
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Originally Posted by moparplowjockey
Also checked plug wires and they all ohm out ok.

That pretty much means nothing.
 
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Old 01-16-2012, 06:12 PM
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I am looking for solutions not someones worthless comments so if you can't help please don't post!
 
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Old 01-16-2012, 06:13 PM
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Originally Posted by HeyYou
Did it have the miss before you changed the cap?
No I didn't it ran fine. Drove it home and shut it off, sat for one day and then wouldn't start.
 
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Old 01-16-2012, 06:21 PM
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Originally Posted by moparplowjockey
I am looking for solutions not someones worthless comments so if you can't help please don't post!

It's the truth and NOT worthless there bud. You had to move the wires quite a bit to uninstall and install the new cap and rotor. Ohm's mean nothing when the truck is running and there is now a potential crossfire that may have not been there before.
 
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Old 01-16-2012, 06:25 PM
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Ah, so, it's entirely possible the two events are completely unrelated.....

Only misses under hard acceleration? If it were the other way, I would suggest the O2 sensor... but, at large throttle openings, PCM ignores the O2 sensor......

Take it for a ride, and drive about 45 MPH....... if you have a consistent miss, it WILL show up there..... If that's nice and smooth...... maybe a cracked plug?
 
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Old 01-16-2012, 06:37 PM
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HeyYou thanks. I am probably just gonna bite it and put plugs, wires and coil in it. Hope this doesn't get expensive changing parts.

Zman17, A single comment does not help. If you know something by all means post it. I am not a mechanic by any means, if I were I wouldn't be on this site asking for help. I am trying to track down a problem without spending a ton of money that I don't have. I understand the cross fire issue but I also know if the wires don't have the proper ohms then they are broke down and won't carry the pulse to the spark plug.
 
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Old 01-16-2012, 06:49 PM
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Ok no problem, lets all calm down.

The inside of the plug wire can be fine and ohm correctly, but if the casing fails you get crossifire between wires or if one is too close to something and worn or cracked. In other words, the spark can jump out of the wire through the casing. Seems to me, if it was fine before, then something got moved or damaged. Vac line crack, the wires for both the crank and cam sensors are right there too.
 


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