Hello all,

I was just wondering if anyone would be able to offer some advice on a particular problem which I've been having with my 2001 'Y' Polo 1.0.

The problem basically is this - I have noticed that my car has quite a jerky throttle response, in as much that even when I lightly lift off the accelerator when decelerating (EG when moving from the accelerator to the brake pedal), the car will noticeably jolt. Sometimes the throttle will 'run on' before decelerating. Also, there seems to be a problem with switching off the engine. It is as if the engine is 'dieseling' (IE Running on for a short time) after it is turned off. The engine also constantly pinks under both light and heavy acceleration, even under cruising speeds).

My question is whether anyone thinks that I may need a replacement throttle body to solve the throttle response, as I know that these can be problematic on the Polo. My car used to have the common Polo 6N/2 problem of erratic idling, which was solved by cleaning the throttle plate, which was howling with built-up carbon. After cleaning this, the engine ran smoothly but the dieseling problem originated after cleaning.

With regards to the pinking issue, I have also heard this problem occurring on similar Polo 6N2s (as well as some modern Ford Focuses!). I know full well of the damage which can occur to the pistons, and was told by my mechanic that the head would have to come off for a decoke. My second question is whether there is an easier way of doing a decoke? I know that stripping the head is probably the only way, although Ecotek sell an aerosol spray which is supposed to burn off the accumulated deposits. I've tried this but apart from the car being a bit more responsive and my wallet being £20 lighter, the pinking noise remains.

Apologies for the chapter and verse, but I thought that there may be a possibility in some of you knowing what would be best.

Thanks again,

Joseph

I would think that it is extremely unlikely that you need to de-carbonise the engine in order to overcome your problem of 'running on'.

It is true that bits of hard carbon will tend to glow under compression, causing the condition, but it is also possible that any small item inside the combustion chambers, including the spark plug electrodes, will do the same thing under the 'right'conditions.

I would suggest two courses of action which you could take before you do any 'drastic'work on the engine.

1) Buy a set of genuine VW spark pugs and fit them.

2) Run two or three tanks full of Shell V-Power petrol through the car. (A single tank full may not make any noticeable difference.)

I know that this petrol is more expensive than regular fuels, but I find that not only does the engine feel smoother, but there is definitely better torque and, I believe, better fuel consumption figures which would probably substantiate their claim that it is cleaner burning.

As for the jerky running, it would pay to check for vacuum leaks after the throttle body and may be also give the TB another clean. It may also pay to get the car on VagCom in order to align the throttle body (and check for any fault codes.)

Regards.

I would think that it is extremely unlikely that you need to de-carbonise the engine in order to overcome your problem of 'running on'.

It is true that bits of hard carbon will tend to glow under compression, causing the condition, but it is also possible that any small item inside the combustion chambers, including the spark plug electrodes, will do the same thing under the 'right'conditions.

I would suggest two courses of action which you could take before you do any 'drastic'work on the engine.

1) Buy a set of genuine VW spark pugs and fit them.

2) Run two or three tanks full of Shell V-Power petrol through the car. (A single tank full may not make any noticeable difference.)

I know that this petrol is more expensive than regular fuels, but I find that not only does the engine feel smoother, but there is definitely better torque and, I believe, better fuel consumption figures which would probably substantiate their claim that it is cleaner burning.

As for the jerky running, it would pay to check for vacuum leaks after the throttle body and may be also give the TB another clean. It may also pay to get the car on VagCom in order to align the throttle body (and check for any fault codes.)

Regards.

Hello there,

Thanks for your advice. It is much appreciated. I was considering running the car for a while on the higher-octane Shell V-Power for a while, in order to determine whether this would improve the pinking problem which I am experiencing with the car. I will do this next time I fill up.

I think that the car is due the 40,000 mile service (at 134,000 miles), which is when the spark plugs will be changed. I was told that these are platinum-tipped spark plugs and do cost a bit more but I don't cut corners with vehicle maintenance and parts.

With the throttle body, I will check to see if it needs a further cleaning. There was a couple of frayed vacuum pipes which were duly replaced a couple of years ago and made no improvement to the vehicle running. I will also get the car on VAG-Com as you suggested, as I remember hearing that the throttle bodies may need reprogramming by VAG after cleaning.

Thank you for your advice.

Kindest Regards,

Joseph

As far as I am aware, genuine VW plugs do NOT have platinum coated electrodes.

From time-to-time,VW seem to change their plug supplier, using either Bosch or NKG.

The all important difference in the GRADE of the plug is in its heat range (this is set during manufacture by the length of the internal insulator)

The longer the insulator, the 'hotter' is the plug.

All plugs that are supplied by motor factors etc. are designed to suit a fairly wide range of engines.

The plugs that are sold by main dealers with the car makers name on it (e.g. VW) are made to a closer tolerance of heat range, due to them not having to cover such a wide range of engines, this gives a better performance in the engines that they are designed for, but, due to the more limited range of sales, there is an inevitable price difference.

When you take the improved performance and length of life into account, the genuine VW plugs give good value for money.

Whilst plug manufacturers all make claims for their own brands, and whilst they may be good quality plugs, few of these have the close heat range required by a particular engine, if they do, it is more by good fortune than by design.

Modified engines of course, may well need a different plug to the ones supplied by the car manufacturer, so some experimentation with heat ranges has to be made in order to find the optimum plug.

I personally would not be tempted to buy a plug with a particular design feature (like platinum coated electrodes) if I was not sure that it was of the correct heat range for my engine.

Regards.

As far as I am aware, genuine VW plugs do NOT have platinum coated electrodes.

From time-to-time,VW seem to change their plug supplier, using either Bosch or NKG.

The all important difference in the GRADE of the plug is in its heat range (this is set during manufacture by the length of the internal insulator)

The longer the insulator, the 'hotter' is the plug.

All plugs that are supplied by motor factors etc. are designed to suit a fairly wide range of engines.

The plugs that are sold by main dealers with the car makers name on it (e.g. VW) are made to a closer tolerance of heat range, due to them not having to cover such a wide range of engines, this gives a better performance in the engines that they are designed for, but, due to the more limited range of sales, there is an inevitable price difference.

When you take the improved performance and length of life into account, the genuine VW plugs give good value for money.

Whilst plug manufacturers all make claims for their own brands, and whilst they may be good quality plugs, few of these have the close heat range required by a particular engine, if they do, it is more by good fortune than by design.

Modified engines of course, may well need a different plug to the ones supplied by the car manufacturer, so some experimentation with heat ranges has to be made in order to find the optimum plug.

I personally would not be tempted to buy a plug with a particular design feature (like platinum coated electrodes) if I was not sure that it was of the correct heat range for my engine.

Regards.

Thanks for your reply. I'll bear this in mind when my car is in for its next service, as I was previously unaware of this.

Thanks again,

Joseph