passat 1.8 20v turbo, hunting idle & hesitating on power

**vwpassat1.8juic** · 08-12-2008,07:09 PM

R-reg 1.8 20v turbo 120k.
recent oil and fuel filter change.
squirted carb cleaner in the idle control valve.
engine is hunting on idle and when you put your foot down it judders loss of power when driving...?
plugged in me sealey VS8650 handheld diagnostic & only code coolant temperature sensor - implausable signal.
would a spark plug cause this.....? or associated wiring...?
and if so why aint the code reader picking up the fault...?
have used the code reader only various other makes of cars and it picks up knock signals ok.....
any help much appreciated

**vwpassat1.8juic** · 09-12-2008,09:29 AM

any point in the right direction would be grateful

**euroslap** · 09-12-2008,09:33 AM

Change the Temp Sender, they cause all sorts of problems when they fail.

**vwpassat1.8juic** · 09-12-2008,11:10 AM

will be changing sensor hopefully soon, i didnt think that would have caused running problems though

**euroslap** · 09-12-2008,02:17 PM

Use the search facility for temp sender, you wouldn't beleive the problems a faulty one can cause.

**kenney** · 09-12-2008,03:56 PM

Hi I had a job on a 20v APT engine last week.Funny thing it had the same symptoms and the same fault code as mentioned.Replaced the temp sender first,but the fault remained,Anyway to cut a long story short, after about 3-4 hours fault finding,the fault turned out to be the air mass meter.What threw me off the track was that the reading from measured value blocks for the air mass meter was correct.And it is not the first time i have been fooled by diagnostic equipment.

**vwpassat1.8juic** · 09-12-2008,05:48 PM

So defianatley wouldnt be spark plug side of things....
Will change the temp sender 1st....
Where is the air mass meter and what would unplugging it and driving the car do if it is faulty - sorry new to this diagnostic game

**kenney** · 09-12-2008,06:03 PM

It might well be ignition related,in your case.I also thought it was the coil pack,since i was getting no fault codes.The air mass meter is on the innlet hose,and is situated at the side of the air filter.

**vwpassat1.8juic** · 09-12-2008,07:04 PM

Whats the big bosch sensor ontop of air filter housing if i unplug it cuts engine out....
If you un plug the Air Mass Meter and test drive it should it drive better or worse if thats the problem....?

**kenney** · 09-12-2008,07:22 PM

I need your engine code to be sure,but i think it is the ,output stage.the air mass meter is to the side of the filter on the hose that runs to the throttle body