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Well there's a surprise

Hi guys.

I have a 1996 1.4 and had 'stalling at junctions' issues. It turned out that the brake servo vac pipe was split at both ends. Bodging it with insulating tape only partly stopped the leak, but the car ran fine.

£17 and a new pipe later, the car idles too slow and hunts badly, and it stalls again
I've done a searchy and read about common problems with the idle control valve, but am puzzled why it ran OK with a slight vac leak.

My other guess is that the previous owner turned the idle speed down to compensate for something.

First question is. Where is the idle speed screw ? (I might be blind but couldn't find it)
Second is. Any other ideas ?

Thanks for any help.

not sure if there is an idle speed adjustment - it may be possible on the throttle body somewhere - but I think that's a VAG thing and is hard to do.

it could have been that the slight leak made it ran fine but that may be a coincidence. try giving the system a darn good cleanout - clean up the throttle body with carb cleaner, new air filter, clean up the filter housing and reset the ecu (disconnect the battery for an hour or so).... the other option is a new water temp sender (loads of posts about that) which is a common fault.

once all that is sorted (only about 25 quids worth) then try looking for other solutions - but that's a good start.

I think the lamda sensor might also cause these problems - it sounds like a sensor could be giving the engine the wrong info..... never done the lamda thing myself - but have a search on the forum

welcome to the site

there was a recall on polos from VW about split servo hoses...so u can get it done for free from VW

there aint a screw to control idle on mk4s, works through the throttle body so dirt can mess it up. Try giving the throttle body a good clean with some carb cleaner and leave the battery disconnected for couple hours

then reconnect it all and take it for a good drive...sorts most idling issues on polos

Yeah I had the same problem a good few months ago!

It was when I was breaking or coming to a stop the Polo would just cut out ... took it to the garage and they cleaned the throttle body and luckily enough haven't had any problems since.

yeah, all the posts about cleaning up the throttle body are right.

but by the sounds of it, u might want to go to a vw dealer and get the throttle body's basic settings re set,should only take about 15 mins, n prob worth it?

hope u get ya prob sorted, let us know...

Thanks for replies.
Car seems to have been running OK since slightly leaky pipe was refitted, but obviously this isn't right long term.

With the air filter housing removed, I could see an electric mechanism moving the throttle butterfly at idle, pulsating and generating the weird idle pattern.

I'll try cleaning throttle body out and battery/ECU reset, but am genuinely surprised there's no idle speed control screw or similar.

Apart from paying Mr Halfords money, is there a technical manual available on the forum ?

AndyH wrote:Apart from paying Mr Halfords money, is there a technical manual available on the forum ?

Better to buy one (Haynes) from ebay - normally go for a couple of quid

There is an electronic version but it's not talked about on the forum as all the copies (also found on ebay) are pirated software......

16vTej wrote:Try giving the throttle body a good clean with some carb cleaner and leave the battery disconnected for couple hours

then reconnect it all and take it for a good drive...sorts most idling issues on polos

wanting to give this a try just 2 thing.
1, where can i get some carb cleaner?
2, will disconnecting my battery cause my alarm to go off / fcuk up??

cheers