Engine reving up and down when using power HELP PLEASE!!

[PEZ_MK2GOLF]

Hi,

I have a mk2 golf 8v gti and have a problem when using power, such as the heater or headlights and wipers together the car will constantly rev up and down to about 2000 revs, i have checked the alternator and its putting out 13.5v and the battery is pretty much the same 13.4v and i have also tried cleaning the idle control valve just to be sure but no changes.

I have a spare mass airflo meter would it be worth putting that on too see if it has anything to do with that side of the car?

now winters pretty much here i would like to get to the stage i can actually use my heater so any help or advice would be great to try fix this

Thanks allot 

[Santiago]

I'm about to pick up a car with the same sort of symptoms. This one has been used very little in the last year, so I'm wondering if it's about the battery's state of charge, and the consequent alternator/engine load.

Throttle body idle switch is another possibility (I read) but the PO reckons that's been checked.
Taking a voltmeter with me when I pick it up & it's 130 miles away, so I should be able to do some before and after voltage measures, and see if the symptoms change from start to end of journey.

Will update tomorrow evening.

[PEZ_MK2GOLF]

Ok cool thanks for the reply seems not many ppl know about it or had same issues so its good to know im not the only one lol would be great to see how you get on thanks,

Good luck matey. 

[Santiago]

Well I didn't get the chance to measure the battery voltage before I set off, but the bouncing revs didn't seem too noticeable either.  At the end of the 130 miles there was no sign of it at all, even with lights on full beam and blower on max.  Voltage at battery with engine running was 14-14.1 with no loads on, 13.8 with lights on (at end of journey).

Not sure this helps you much, except maybe to suggest taking it for a decent run and/or cleaning the mountings/contacts of your alternator's voltage regulator to try to get from 13.5/6 up to nearer 14V.

Good luck.

[PEZ_MK2GOLF]

No that helps allot thanks, there that was the next thing on the to do list is to clean the contacts thanks agsin and enjoy you golf.