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Discussion Starter #1
I have a 2001 Focus ZTS 16V ztech. My problem started a few months ago very intermitently. I would be driving, suddenly RPM would shoot way up, temp gauge drops all the way down and engine lights come on. After RPM stabalize, temp gauge returns to normal and lights go off, maybe lasting 8 seconds. Now its everyday and sometimes i can not even move the car because it idles between 3 and 4 thousand rpm, making it shift very hard trying to put in gear. PCM and mass air flow sensor have been replaced, did not solve issue. I believe it is a wiring issue, just not sure where to start. Any suggestions would be great, thanks.
 

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Welcome to ff, I have no idea what would cause that but I'm sure others will chime in. My guesses would be an alternator problem maybe a bad coil or connector on one of these.

In the meantime a few questions. Did you scan for codes, if so what were they? Also what led you to replace the pcm and maf?
 

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The PCM and MAF sensor were replaced by the previous owner who had in to a dealer for the same concern. I have scanned and it is throwing 6 codes. P\
P0113 - intake air temp. sensor 1 circuit high
P1289 - cylinder head temp circ. high input
P0123 - throttle/pedal/position sensor switch A circuit high
P0190 - fuel rail presure sensor A circuit
P0193 - fuel rail pressure sensor A circuit high
P0453 - evap emission system pressure sensor/ switch high

I have a wiring diagram that i got from "All Data" which involves almost all of these codes which leads me to believe that it is a wiring issue i'm just unsure where to start. I am not sure if there is some miscommunication between the trans and the PCM or what. Any advice would be great, thanks for the reply to my post...
If you have any more ideas feel free to share them .

Thanks!
 

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I don't have a clue but with this info hopefully somebody else will chime in. Lots of people were at focusfest over the weekend so today is caravan home or recovery day for many.
 

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Yeah, you definitely need to check your wiring harness around the EGR tube. If I'm not mistaken, that's the one that I'd call the EFI harness, and it's been known to get burned. Sometimes the burn is not easy to see from above. You might have power crossing over onto sensor returns to the PCM.
 

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yeah, in fact a few months ago back when it was a very mild, and intermitent issue, i origionally thought it was something to do with the copper pipe that comes off of the EGR. I read that over time the metal cracks and can worsen with time. Through lots of discussion, people lead me to think otherwise and i kind of ruled it out. Funny you bring it up because its still kind of been on the back burner of my mind. Your saying its possibly the wiring harness that burned or melted and not the tube that cracked? Would the EGR issues explain all of the symptoms? Or could it be a combination of that and another, or more than one factor?

*One more thing ruled out, i found a calapsed PCV hose that i replaced yesterday, did not help. Could another vacume issue somewhere else still be a factor?

Thanks for the reply...
 

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yeah, in fact a few months ago back when it was a very mild, and intermitent issue, i origionally thought it was something to do with the copper pipe that comes off of the EGR. I read that over time the metal cracks and can worsen with time. Through lots of discussion, people lead me to think otherwise and i kind of ruled it out. Funny you bring it up because its still kind of been on the back burner of my mind. Your saying its possibly the wiring harness that burned or melted and not the tube that cracked? Would the EGR issues explain all of the symptoms? Or could it be a combination of that and another, or more than one factor?
Could be both. If the EGR tube has a small crack it would be blowing hot exhaust onto your wiring. That could result in shorts in the wiring as well as tripping a bunch of codes. It is at least worth looking over very well.
 
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