Hi Guys and Girls.

I'm going to do my best and explain the problem with my 2001 Octy VRS.

1. When starting in the cold, the revs start high and drop to about 500rpm and the car sound like a bag of spanners and struggles to stay running.

This morning the car actually stalled a couple of times.

2. When hot and running normally the car drives like a dream but when I stop at the lights the revs drop to about 600rpm and again the car struggles to continue running. I had a look at the engine when idling and it looks like its right on the cusp of stalling, :( revving up and down slightly.

If I turn off the ignition and turn it back on the car will idle normally.

3. A list of thing I have already done.

a. Cleaned the Throttle body.

b. Replaced coolant Temp sensor.

c. Changed Y piece breather pipe on r/h side top of engine as it had split.

Please please help. This is doing my head in.

Thanks folks.

Phil

I had the same problem with cold start, it was the fuel filter.

Try this in the morning; turn several times ignition key on/off and then start the engine. If engine idles without problem after this then you need to change the fuel filter.

Hope this helps

Edited 23 February, 201016 yr by Gonzaga

I had the same problem with cold start, it was the fuel filter.

Try this in the morning; turn several times ignition key on/off and then start the engine. If engine idles without problem after this then you need to change the fuel filter.

Hope this helps

Thanks, I will try that in the morning, Keep the suggestions coming guys and girls.

Have you tried fault code scanning it? Mine had starting issues where the revs would be all over the place and it was throwing a 17704 fault code which was an issue with the coolant system, I replaced the coolant temp sensor first which didn't help then replaced the thermostat which got rid of the code. The multiplug to the temp sensor was also broken. With all 3 of these things fixed it now idles ok after starting.

If you scan it and get a 17705 code there is probably another hose loose or split somewhere.

Could also be a faulty throttle body. A clean can help if it's dirty but they do fail as well unfortunately not a particularly cheap part to replace either.

Edited 23 February, 201016 yr by chicken_eyebrow

Have you tried fault code scanning it? Mine had starting issues where the revs would be all over the place and it was throwing a 17704 fault code which was an issue with the coolant system, I replaced the coolant temp sensor first which didn't help then replaced the thermostat which got rid of the code. The multiplug to the temp sensor was also broken. With all 3 of these things fixed it now idles ok after starting.

If you scan it and get a 17705 code there is probably another hose loose or split somewhere.

Could also be a faulty throttle body. A clean can help if it's dirty but they do fail as well unfortunately not a particularly cheap part to replace either.

How did you go about changing the Multiplug or testing it?. I have had the car scanned and I had 17704 and 17705 fault codes, unfortunately I haven't been able to test it again to see if the faults have returned, though the light had came back on. I assumed the 17705 code was due to the split engine breather Y shaped hose on the top r/h side of the engine that I found and changed. The light came back on before I found this split hose.

Cheers for the suggestion.

Hi Philevo,

It could be several things you dealing with, but you can try out these things first.

Number 1

This could be the misfire and when misfire occours not always ecu will pick up the misfire fault !

This misfire normaly occurs when engine normaly cold due to a spark pressure, but once engine warms up it dissapears. This is not a common problem on pencil ignition coil pack but this can happen.

Number 2

Could be your auxilary air pump (not working), when engine is cold this pump is suppose to come on and inject more air in the system and ecu will automatically inject more fuel without realising that auxilary pump doesnt work. This will result in rich mixture and engine will not run properly.

Number 3

Unwanted air in the intake system, check this carefully. When engine is not running ok, buy some easy start and spray it aroud the inlet manifold and observe engine rpm. If rpm increases then this will point to air leak.

Number 4

Adaption on the throtlle body, basic settings required.

Let us know how you get on

Hi Philevo,

It could be several things you dealing with, but you can try out these things first.

Number 1

This could be the misfire and when misfire occours not always ecu will pick up the misfire fault !

This misfire normaly occurs when engine normaly cold due to a spark pressure, but once engine warms up it dissapears. This is not a common problem on pencil ignition coil pack but this can happen.

Number 2

Could be your auxilary air pump (not working), when engine is cold this pump is suppose to come on and inject more air in the system and ecu will automatically inject more fuel without realising that auxilary pump doesnt work. This will result in rich mixture and engine will not run properly.

Number 3

Unwanted air in the intake system, check this carefully. When engine is not running ok, buy some easy start and spray it aroud the inlet manifold and observe engine rpm. If rpm increases then this will point to air leak.

Number 4

Adaption on the throtlle body, basic settings required.

Let us know how you get on

Thanks for the info. I was under the impression that the throttle body could not be adjusted as it has Electronic Pedal Control or something like that anyway.

I had an idea that it could have been the secondary air pump failing but would that stop the fault when the car is warm, I had read that the air pump only operated for about 90 seconds so the fault should go away after that? I'm not sure like, just what i read. My car seams to have problems idling even when hot.

I'll add your item to my list of things to check.

Cheers

when you did the TB clean did you disconnect the plug? or was it very dirty? if either is true then you will need to run TB adaptation. Also how long ago did you repair/replace the Y Pipe as this would have caused a VAC leak which the ECU would have adapted to, when it got replaced you should have cleared any codes which also clears the adaptation values in the ECU causing it to relearn how well the engine is running. A good example of how much this can affect the car was when I did a leak test on mine and forgot to clamp the TIP back to the MAF properly, causing the mother of all VAC leaks, I then fixed it and the car ran like a bag of spanners, cleared the codes and all good again. HTH

How did you go about changing the Multiplug or testing it?

You could see the multiplug was knackered, whoever had the car before me had tried to pull it off of the coolant temp sensor and broken the clip on it so it wasn't clipping into the temp sensor properly. When I replaced the temp sensor I tried to stick loads of electric tape on it to hold it on but in the end I took it to a garage and they soldered a new multiplug on I think it was about £30 for the multiplug repair kit and £50 for an hours labour, you could do it yourself if you're confident with soldering in a very tight space!

As Karl said it's important to clear codes once you've solved any problems, if you can get a local member to VAG-Com it, clear the codes, then drive it for a bit and then scan it again and see if the codes come up again. If 17705 is still coming up then look for other vaccum leaks in other hoses / valves and if 17704 is still coming up then consider the thermostat or temp sensor multiplug if you've changed the temp sensor itself already.

when you did the TB clean did you disconnect the plug? or was it very dirty? if either is true then you will need to run TB adaptation. Also how long ago did you repair/replace the Y Pipe as this would have caused a VAC leak which the ECU would have adapted to, when it got replaced you should have cleared any codes which also clears the adaptation values in the ECU causing it to relearn how well the engine is running. A good example of how much this can affect the car was when I did a leak test on mine and forgot to clamp the TIP back to the MAF properly, causing the mother of all VAC leaks, I then fixed it and the car ran like a bag of spanners, cleared the codes and all good again. HTH

Thanks for the info that's really helpful. I did not disconnect the throttle body and I have not had the faults cleared since changing the Y piece but will certainly get it done now. Do you need a fully registered VAG-COM to do the adaptation?

Cheers again

Phil

WAAAHHHHOOOOOO.

Got the problem sorted. I took the advice to get the faults cleared and get the adaptation done on the Throttle Body.

I also decided to give the air temp/pressure sensor a clean as it is next to the throttle body, sure enough it was filthy, I would recommend doing this when you clean the throttle body as it does get very dirty.

The idling went better when hot but not perfect. I when to VW and AUDI specialists in Hoylake Wirral and they done the adaptation and cleared the faults, they also

welded a mount on my exhaust as it was snapped, £68.00 all in so I'm glad to report that the red weapon is paring like a kitten.

Thanks for the advice.

Phil

Good stuff, that sounds like a very reasonable price too

Glad you got it sorted

I couldn't resist