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Post by mayfly on Oct 21, 2014 18:54:03 GMT 1
This is a 2007 1.4 focus petrol. Runs rough at times and can also hunt quite badly. I scanned it and have 2 fault codes po102 mas airflow circuit low input
and po458 EVAP system purge control valve circuit low. I also noticed that if I try to clear codes with engine running the po458 EVAP code will clear and the car will run perfectly ,the air flow code won't errase. Then when you restart engine it's back to rough idle. I changed the Amf from another car but still no joy . Any ideas, cheers.
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Post by Karl on Oct 21, 2014 19:07:30 GMT 1
Was it the correct part no ? There's a learn procedure to do. Ignition on for 1 min , may need your scan tool to reset learn values
Have you a wiring diagram?
ref voltage,ground and feed voltages been tested ?
Seen duff PCM cause this
But further checks are needed first
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Post by valhalla on Oct 21, 2014 23:16:47 GMT 1
Sorry for asking the obvious, but have you leak-checked the EVAP circuit (or, indeed, all of the induction system for completeness)? It might be that a major leak on the EVAP circuit would be enough to pull the MAF signal down to a level to trigger the fault there. I'm not as familiar with the Focus 1.4 as many people on this forum, so don't know if this has been seen as a "usual cause" or not?
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Post by Karl on Oct 21, 2014 23:33:47 GMT 1
Sorry for asking the obvious, but have you leak-checked the EVAP circuit (or, indeed, all of the induction system for completeness)? It might be that a major leak on the EVAP circuit would be enough to pull the MAF signal down to a level to trigger the fault there. I'm not as familiar with the Focus 1.4 as many people on this forum, so don't know if this has been seen as a "usual cause" or not? Very few 1.4 mk2 focus around Inlet vacuum leaks are not uncommon on zetec engine |
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Post by Rhubarb on Oct 22, 2014 0:05:30 GMT 1
Does sound like a vacuum leak, it's just finding it innit...
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Post by Deleted on Oct 22, 2014 14:09:19 GMT 1
This is a 2007 1.4 focus petrol. Runs rough at times and can also hunt quite badly. I scanned it and have 2 fault codes po102 mas airflow circuit low input and po458 EVAP system purge control valve circuit low. I also noticed that if I try to clear codes with engine running the po458 EVAP code will clear and the car will run perfectly ,the air flow code won't errase. Then when you restart engine it's back to rough idle. I changed the Amf from another car but still no joy . Any ideas, cheers. clearing a code when engine is running ? and this then makes it all of a sudden run perfect ,  |
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Post by mayfly on Oct 22, 2014 20:12:57 GMT 1
Thanks for replys and suggestions. Had another look today, checked for air leaks ect but didn't have a wiring diagram, however as Mr Benze suggested I discovered I was missing a 12 v feed to Amf. Striped back and found a break in the wire, repaired it and all well again.
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