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Kevin
Kevin, UK Car Mechanic
Category: UK Car
Satisfied Customers: 1434
Experience:  Diagnostic technician at vw /audi specialist
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I have a 55 plate Peugeot 206 1.4Hdi which hunts at idle

Customer Question

Hello Mike, I have a 55 plate Peugeot 206 1.4Hdi which hunts at idle when at normal operating temp (never when cold), if I unplug a sensor, temp sender, MAP, MAF whatever it immediately stops hunting and runs normal (until sensor plugged back in). EML comes on form time to time (days between) but there doesn't seem to be any pattern. I have run a scanner and get fault code P0069 but not sure if this is a different problem. Car seems to run well apart from this. Only mod is I have blanked the EGR valve but that was years ago so I can't see how it's linked, any ideas? Thanks, Peter.
Submitted: 1 year ago.
Category: UK Car
Expert:  Kevin replied 1 year ago.

Hi I'm Kevin I will try and help you .so just to clarify which sensors you are unplugging to give improvement?

Customer: replied 1 year ago.
Hello Kevin, I need to go out later so will re-try when engine is warm but water temp is a definite and it was a while ago but I'm fairly sure it was also any of the others (MAP MAF IAC) I will double check later (engine cold at the moment)
Expert:  Kevin replied 1 year ago.

Ok the code is referring to a air pressure coherence problem so the air pressure in manifold that is being measured is not what the car is expecting to see the most likely cause is either map sensor or maf sensor

Customer: replied 1 year ago.
Okay thanks for that, I have already checked vacuum pipes (all okay) and replaced the MAP (cheapest component) and the fault went away but only for a week or so. I was reluctant to to try the MAP due to it's cost but if you think it's a likely candidate I'll give it a go.
Customer: replied 1 year ago.
Sorry I meant MAF due to it's cost
Expert:  Kevin replied 1 year ago.

There are a few options other than that but it sounds as though you have already covered them

air leaks

blocked air filter

map

maf

how long has egr been blocked I'm assuming not a recent thing ?

Customer: replied 1 year ago.
Not recent, egr was blanked off years ago, air filter okay and can't find any other air leaks. Off to collect my daughter from the station shortly so I'll unplug each sensor in turn when I get back (engine will be warm by then)
Expert:  Kevin replied 1 year ago.

That's what I though let me know how you get on

Customer: replied 1 year ago.
I will, thanks.
Expert:  Kevin replied 1 year ago.

No worries

Customer: replied 1 year ago.
Hello Kevin, unplugging either the temp sender, MAF or IAT sensors stops the problem, the MAP sensor has no effect.
Expert:  Kevin replied 1 year ago.

I still suspect a maf fault it fits with the code as it's showing a difference in air pressure

Customer: replied 1 year ago.
Okay I'll break open the piggy bank and get one, tomorrow if I can. I'll let you know the result, many thanks, Peter.
Expert:  Kevin replied 1 year ago.

No worries let me know how you get on

Customer: replied 1 year ago.
Good morning Kevin, fitted new MAF yesterday but unfortunately made no difference, checked again this morning after a run but fault is as before. What's confusing me is idle is perfectly smooth during warm up and by disconnecting the temp, MAF or IAT sensors, so surely it can't be a physical problem ??I found a youtube clip of somebody else engine doing the same thing, hope that helps.https://www.youtube.com/watch?v=vwMdEJbwH8Q
Customer: replied 1 year ago.
Good morning Kevin, fitted new MAF yesterday but unfortunately made no difference, checked again this morning after a run but fault is as before. What's confusing me is the idle is perfectly smooth during warm up and also by disconnecting the temp, MAF or IAT sensors, so surely it can't be a physical problem like vacuum leak or sticky throttle body as then it would be there all the time. The MAF is reasonable as there is some electronics in there so a shame it's not that. I had the thought it may be an ECU map problem, although I don't know how as I've owned the car from new and that's never been touched. I hope you have some ideas.I found a youtube clip of somebody else engine doing the same thing, hope that helps.https://www.youtube.com/watch?v=vwMdEJbwH8Q
Expert:  Kevin replied 1 year ago.

That is very strange you got me stumped no I will opt out this will add question back to list to see if another expert can assist I'm sorry I couldn't help more

Customer: replied 1 year ago.
That's fine, thanks for trying.