polo 1.4 idle problem

**gav25** · 11-04-2007,08:06 PM

Please can anyone out there

me? I have a 1.4L 1999 vw Polo. The problem is that every time I am approaching a junction, it cuts out and the battery light comes on. It also only idles at between 500 and 800 rpm? which is much to low, can you adjust the idle speed? if that is what it is, or is there anything else it could be? Its had a full service not long ago and the problem is still there. Anyones feedback would be much appreciated.......cheers

**ndpster** · 29-09-2007,02:20 PM

2003 1.2l Polo. Same problem, no answers I'm afraid. I'm just worried that it's something computer related and thus expensive to fix!

Ster.

**Crasher** · 29-09-2007,03:23 PM

Both of you can stop worrying for the moment. All you need to do to start with is have the throttle body (TB) cleaned and reset but this isn't as simple as it sounds. The throttle body needs to be removed, which is easy, and then very carefully cleaned internally using aerosol carb cleaner and a stiff nylon brush. No sharp scrapers or abrasives must be used and the internals need to be spotless with special attention paid to the spindles where they go into the body and to the edges of the butterfly. After the TB has been refitted it needs to be readapted to the ECU. If it isn't, the idle will be very high. This is done using diagnostic equipment such as VAG-COM in Basic Adjustment mode 04, and display group 001 for early cars (nether of these two), 098 for later cars with a cable throttle and display group 060 for Drive By Wire cars which the 2003 is but the 99 probably isn’t. The 2003 Polo has an Exhaust Gas Recirculation (EGR) system that unfortunately complicates matters as EGR deposits build up under the TB and are extremely difficult to get off, often requiring very careful scrapping with a plastic scrapper and gentle polishing off with an abrasive pad such as Scotch Brite but this must be done extremely carefully as any scratches in the aluminium body or on the butterfly can cause sticking which is at best irritating and could be dangerous. Don't let a garage push you into a new TB though, in 99% of cases this is not necessary and ECU failure is extremely rare. One other point is that on the 3 cyl 1.2 model it is easy upset the ECU when resetting the TB so it needs to be done by someone who knows what they are doing, otherwise you can end up with them thinking the Manifold Absolute Pressure (MAP) sensor is faulty, fitting a new one and then realising it is an EGR adaptation fault so money gets wasted.

**ndpster** · 29-09-2007,05:58 PM

Thanks for the advice. I'll let you all know how I get on.

Ster.

**Tomangela** · 11-10-2007,09:18 PM

I've had this problem for a while on my 2002 Lupo 1.0L. I cleaned the throttle body out this eve with some carb cleaner and an old toothbrush!

I didn't bother disconnecting anything. I just flipped it over and cleaned out all the gunk. I also sprayed some carb cleaner in afterwards while running. This way I haven't had to reset the computer.

I hope I haven't caused any damage, but it seems to be running grand thus far!!!

Let us all know how you get on.

**Crasher** · 11-10-2007,11:07 PM

The ECU will have adapted to the dirty TB so you should still clear and re adapat.

**Tomangela** · 12-10-2007,12:24 PM

Cheers for the advice.

It's still working fine today, but I'll have a look at re-adapting the ECU.

I'm still trying to work out my VAGCOM but I'll do it as soon as I can!

**ndpster** · 28-10-2007,06:36 PM

Matters are turning for the worse. The throttle housing was cleaned; the VAG fault finder identifies a faulty temperature sensor which was replaced. The fault had not been rectified. Latest theory is that the timing chain has slipped (timing is definitely out). £60 for the repair kit but 4-5 hours to fit it…

**Crasher** · 28-10-2007,08:53 PM

Yes, this is a huge problem. Just pray it hasn't clipped a valve, I have only seen a few that have escaped. If you do it yourself, you will need the locking tools. £60 only gets you the chain and tensioner, the two guides are another £13 the pair. The guide between the top sprockets should be deleted according to the new specs and I also like to change the sprockets. Are you saying the CTS fault will not clear?