Polo MK4 idle help

[MrSkins]

Hi all,
A couple of days ago I serviced my sister in laws Polo L, 1998 1.4 bog standard.
Changed usual, plugs, air filter,coolant, oil & filter. While the airfilter was off I thought it looked pretty black down the throttle intake so sprayed some carb cleaner down its throat.. oops when we struck her up the tick over was 1500rpm and would not change even whan warm. Today I tried it again just incase some muck was left on one of the sensors, nope now it revs at 2000rpm with regular peaks at 2300rpm... my arse is on the line with the wife... help..


Thanks in advance.

Simon

[DScape]

Hi all,
A couple of days ago I serviced my sister in laws Polo L, 1998 1.4 bog standard.
Changed usual, plugs, air filter,coolant, oil & filter. While the airfilter was off I thought it looked pretty black down the throttle intake so sprayed some carb cleaner down its throat.. oops when we struck her up the tick over was 1500rpm and would not change even whan warm. Today I tried it again just incase some muck was left on one of the sensors, nope now it revs at 2000rpm with regular peaks at 2300rpm... my arse is on the line with the wife... help..


Thanks in advance.

Simon

Disconnect the battery for a while dude, should reset itself hopefully.

[MrSkins]

Thanks, Just been out removed the earth for about 20mins.. sadly still the same.



Cheers

Simon

[Mint]

I have had the exact same problem as you.

I left mine for a week hoping it would sort itself out; it seemed to get worse, eventually idling at 2300 rpm. Therefore i called out a mobile tuning fellow who brought his van to my house and connected the computer to my car. From there he used VAG-COM to attempt to reset the basic settings, this had little effect. Then he realized that no matter how hard the engine was run, the temperature of the coolant read out at 27.3 degrees. We knew this was wrong, so he substituted the temperature sensor in my car for one he had and the engine ran far smoother, idling at 640 - 900 rpm. He charged us £30 for the diagnostics and advised us that all would be fine after a trip to VW to buy a new sensor. So i did just that and the sensor cost me £27. After replacing it, the car runs so much smoother at idles at a constant 900 rpm.

I would never have thought that spraying carb cleaner would damage a temp sensor, but in my case it did

You can only try; it saves you £300 trying to buy a new throttle body. [/i]

Other than that, i would certainly reccommend a mobile tuner - have a look in the yellow pages. He saved me loads of time and cash.

[MrSkins]

Wow, that sounds like the cause. I will pop along the the VW place tomorrow and get one ordered. By the way you said temp sensor is that attached to the throttle or somewhere on the water system?

Thanks for your help you may have just saved my bottom.

Si

[Mint]

Its connected to the water system. Its below the distributor cap and above the flywheel housing. Really hard to explain without a picture; id get one but its too dark now. Ask VW for a four-wire (or maybe four-pin) temperature sender and theyll know exactly what your talking about after asking you the year of the Polo etc. Ask them if they could tell you where its located too.

Keep some coolant fluid handy too, and be sure to release the pressure of the coolant expansion tank before unplugging the sensor as the fluid will come gushing out; i was scalded and lost half of my coolant fluid by not doing this!

Have you ever experienced random starting problems, smoke on startup, and was the car idling higher than it should have before using the carb cleaner? (eg. 1000prm)

Youll notice great improvements once this is replaced as the ECU is largely dependant on this one sensor; youll also save on fuel costs.

[MrSkins]

The car was actually running absolutly fine before I got my greasy paws on it... Its only since I serviced and blasted it with carb cleaner, strange how it would effect the temp sensor but I'm willing to try anything. I will call in at VW tomorrow.


Thanks again..

[DScape]

Temp sensor was my next guess, then after that...the dreaded throttle body.

Fingers crossed dude

[MrSkins]

Just got back from VW and sadly it is the throttle body so now on the hunt for one. Is this a common fault?

[DScape]

Just got back from VW and sadly it is the throttle body so now on the hunt for one. Is this a common fault?

Aii it seems to be mate. Hoped it wouldn't be that

http://www.volkswagenspares.com/

Good luck mate.

[The_phat_controlleruk]

Quick question, I know this subject has been done to death but, I have been suffering from this same prob for some time, manage to bodge it for the moment to get the car drivable. My question is, when you turn the ignition on, should the butterfly valve open (mine opens about 4mm), and emits a low buzzing sound from the throttle body. When you disconnect the potentiometer (leaving the ignition on), the buzzing stops and the butterfly closes.

[MrSkins]

Hi peeps,
Well at last got the problem sorted, I bought another throttle body from eBay for £70 fitted it and took it back to VW to get it reset.. bugger still ticking over at 1800rpm. The mechanic then said have you tried the temp sender, red faced I said no so he unplugged it and hey presto ticking over at 950rpm so now after a new sender (£27) its running like a dream...

Throttle body and manifold going spare anyone???

[Mint]

Well lets face it..its not as if i suggested that did i??

[The_phat_controlleruk]

Right, went and bought a new temp sender for my ride. Disconnected the battery for half an hour. Fitted new temp sender in mean time. Re-connected battery, initially just turned the ignition on, did not fire her up. Throttle body made all sorts of whiny noises, then eventually stopped. Started her up and she just would not idle on her own, needed some gentle persuasion. Eventually she would idle around 900, EUREKA!!!!!!!! I thought, problem sorted. Took her for a quick blat round the block, all seemed well, on the way back home the idle started creeping up and up, now she's back to where she was, 1500+ rpm. Someone told me it could also be the MAF in the intake manifold, could this be true, I had a price for a new one at Eurocarparts, £127.00. He even kindly told me I can't just go to a breakers or get a second hand one, it HAS to be a brand new one, WTF. Mind you, since fitting the new sensor, she does not burn petrol like she used to, before, she would smoke like mad when first started, like she was burning rich. Doesn't do that now, also the readings on the temperature guage seem to be a bit more accurate than before.

[The_phat_controlleruk]

Help ???, Pleeeeeeease (picture of me on knees)