Author Topic: 16V Weird Idle/Throttle Response  (Read 452 times)

Offline Stirring Moose

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16V Weird Idle/Throttle Response
« on: 03 April 2022, 19:01 »
Hi everyone,

Haven't been on the forum for literally years because health stuff meant giving up driving license, then lockdown happened blah blah blah. In short, not much VW action for me of late.

Anyway, I'm back now and I've been out tooling around in my '95 16V. All going swimmingly until recently it's started idling erratically, stalling (and sometimes being reluctant to restart), stumbling when I open the throttle etc. Now I'm a bit out of practice with all this so go easy, but here's my thoughts so far:

Vacuum Leak: Have gone over everything. Found one small pipe that wasn't looking great. Fixed that but got no improvement.

ISV: Everything I've read thus far points to this being a classic case of dodgy Idle Stabilisation Valve. I've had it off and given it a really good clean. Also did the sound check - turned the ignition on but didn't crank and valve made suitable noises to indicate life. The one thing I haven't done as yet is an electrical test with a multimeter. I've found resistance values for the three pin ISV but I think mine is a two pin type. Does anyone have figures for these? Secondly, I have seen references to testing the output from the plug but again, no definitive figures for what I should see on the meter. Again, any ideas anyone?

Charging Rate: I'm a little suspicious of the charging rate. Initially, just by applying logic (problem seemed worse when lights etc. were on) I thought it might be undercharging. I put the multimeter across the battery today, ran the engine and got a reading of 14.4V. It seemed steady but it's higher than the 14V absolute maximum quoted in the Haynes manual. I've read about overcharging being an issue. Could this be enough to be causing problems?

Fault Scan: I know this is an obvious route and I'm on it. Just means unearthing the ancient laptop that I use to run VAG-COM and making sure it hasn't kicked the bucket, making sure I can remember what to do etc.!

Any ideas gladly received - it's just so nice to be back playing with old cars again!  :angry: :grin:

S.M.
Love and hate, war and peace, joy and sadness... all just crap that happens between trackdays!

Offline bobfrankish

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Re: 16V Weird Idle/Throttle Response
« Reply #1 on: 07 April 2022, 12:30 »
Hi, you sound like you have had similar issues to me, didn't lose my license, but definitely lost the will and ability to do anything with my old cars! You may want to try the www.vwaudiforum.co.uk, register and go to the Golf MK3 section. I have had much more luck with replies, particularly with reference to the current fault I am trying, unsuccessfully I might add, to get to the bottom of. I don't know much about the 16V I'm afraid, but I think you are on the right lines, dig out the old laptop (good luck with its' battery which always fail!) and see what the infuriatingly basic ECU has to say by way of DTC's, but try not to be too optimistic.

Offline WeekendMechanic

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Re: 16V Weird Idle/Throttle Response
« Reply #2 on: 12 April 2022, 20:38 »
I know this might sound dumb but have you tried a restart, try disconnecting a battery lead and leave it off for 15 minutes then try again.
Worked for me last Monday it seemed that the ECU just needed a refresh, has not done it since.

Offline Stirring Moose

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Re: 16V Weird Idle/Throttle Response
« Reply #3 on: 13 April 2022, 14:58 »
Thanks for the replies with suggestions.

I will try the VW/Audi Forum. I've been reading posts on lots of different forums and sites but, as is so often the case, there isn't quite the little nugget of info you're after lol!

I'm not sure it's an ECU refresh that's required as it's effectively had that in that it was off battery for a while recently being stored. Will keep it in mind as an option though.

Think my next stop will be the aforementioned fault scan (laptop permitting) and a clean of the throttle body, as quite a few people seem to mention that as a cause of similar issues.

Will keep you all posted.

S.M.
Love and hate, war and peace, joy and sadness... all just crap that happens between trackdays!

Offline WeekendMechanic

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Re: 16V Weird Idle/Throttle Response
« Reply #4 on: 20 April 2022, 20:35 »
Sounds like a plan.
Good luck.