UK-POLOS.NET - THE VW Polo Forum

Well the eagle eyed amond you will know of my stupid EPC light coming on and the check engine light and how much it really did drive me so mad I almost drove it into a tree.

Anyway, it went to VW 3 times, waited with them a whole weekend for WV technical, yadda yadda yadda, had to hire a rental car etc, extremely peed off about the whole thing, and was loosing hope, when I bought a copy of everyday mechanics magazine from borders in town.

It didn't have the answer, but it did have an engine diagnostic doctor section in it. I contacted him (Simon) and we talked over the symtoms. and we were hard placed to figure it out. I told him of the intermittent fault code (MAP sensor) so he suggested that I could replace that with another 2nd hand one, to isolate it. It didn't work. However he then suggested I do the following to the letter:

Remove all air filtery crap.
Remove throttle body
Clean all the crape off the back of the throttle body plate
Replace the throttle body gasket.
clean as much of the inlet manifold as I can reach without dismantling it.
replace all air boxy stuff.
fire up vag com, with the engine turned off, go to engine > then channel 60, then [switch the basic settings]. The throttle body winds itself open, then closed fully the cracks open a bit and resets itself up.
Warm up engine on idle until golden brown and fluffy.

After which it drives totally different, no more choking, no more revs droping and lack of torque at idle. It tries to overrun now (which it was supposed to)

Not seem that pesky light since and have done over 500 miles so far (finger crossed) I'm pretty happy to say its it fixed. If it happens again I will find this post and let you know.

finally yey!

Stupid engine management, thinks its knows best... Whose the engineer now eh? Self adapting idle program my arse. I was just about to adapt it with a 20lb hammer!!

Well done.............

Im glad you got it sorted mate.

Always reading about the hassle youve had with that - nice one..

Nice one m8, glad you finally sorted it out.

Im having the exact same issue with my Polo now, changed the MAP sensor for a brand new one, but not sure if sorted it, as I can't clear the check light...

Problem im having is with Vagcom... I can't access "engine", tried with car off like you have above and get a 'no response from controller, retry?' error and then if i turn key so lights are on dash, get a 'cant sync controller' error any ideas why this is happening?

I assume the error code is stored in this controller (engine)?

Any advice would be fantastic m8. Going to try clean the crap off as you did asap to see if it helps (IPA is okay and a rag is okay to use?)

But if i cant access the engine controller option in the program, i wont be able to access channel 60 to reset the throttle body after cleaning it

help

Do you have a non standard radio, i.e. other than gamma or beta? The k-line data line is open collector, which means the VAG lead should pull it high to access the data, however, non standard radios pull that data line all the way to 12V, buggering up the VAG-COM lead.

see http://www.ross-tech.com/vag-com/aftermarket-radio.html

If so, hope that your lead is ok and yank out your radio, including any aftermarket harness. (for now)

If this is not your case, then the next thing that I would guess would be a problem with the serial interface. VAG data packets are not quite the same as RS232, but quite close, so the software does some naughty things to get it to work, including hardware bodges. This works ok on a standard 'hardware' serial port, but serial ports date back to 1970's so, newer stuff doesn't have them. We have USB>Serial converters these days, but they are pretend, and whilst they pretend to be fudged, the emulation is such that they actually conform to the RS232 specification far too well. So many of them will not work with VAG-COM, which is why Ross Tech have made newer USB specific versions.

However that said, I know this one works dandy, because it is what I am using.... ZP43W from maplin, 20 quid to you. I have that plugged in to my tablet PC (Acer) and it works really well. It syncs on the 3rd protocol, which is normal.

If that works, you might find that the engine will not start when it is plugged in, this is ok, as long as the ignition is on, you can poke around. Obviously ignition is off nothing will happen. You can also try to re-adapt the throttle body without cleaning it, or just being lazy and squirting halfords carb cleaner down.

inder wrote:Nice one m8, glad you finally sorted it out.

Im having the exact same issue with my Polo now, changed the MAP sensor for a brand new one, but not sure if sorted it, as I can't clear the check light...

Problem im having is with Vagcom... I can't access "engine", tried with car off like you have above and get a 'no response from controller, retry?' error and then if i turn key so lights are on dash, get a 'cant sync controller' error any ideas why this is happening?

I assume the error code is stored in this controller (engine)?

Any advice would be fantastic m8. Going to try clean the crap off as you did asap to see if it helps (IPA is okay and a rag is okay to use?)

But if i cant access the engine controller option in the program, i wont be able to access channel 60 to reset the throttle body after cleaning it

help

To clean it properly use Wynns carb and injection cleaner (purple can) from halfords for a fiver. Be careful though, because its very corrosive, I melted a toothbrush, and the piping under the kitchen sink, oops. Also avoid getting it on the seals too much, so best to remove the throttle body. Do not attempt to reuse the gasket under the throttle body, obtain a new one (£4 from VW), if you get a vacuum leak under the throttle body it really will drive like a bag of terd, and will fail the MOT miserably.... Can you tell I did that once????