Hi,

I have a 1996 polo 1.4 which sometimes used to start-up then die after a second or so. After many hours of investigation it turned out to be the immobiliser that was causing the problem.

There is a chip inside the key which when the engine fires sends a signal to the 'chip reader' which is a small black box in the fuse section directly under the steering colum. The connectors to this box become oxidated after time and need cleaned/replaced. If the chip reader cannot send a signal to the engine management system the engine will shut down. Once I cleaned these connections (by taking the connecting leads off/on several times) the problem stopped.

It sounds like you may have several problems but this may fix one of them.

Hi GaryBuz, i tried looking for this black box, but could not find it. Where exactly is it please?

I've attempted to upload a photo here so hope it works, what i'm refering too is the black box in the middle of the picture, think there are 2 wires going into it, can't remember which one to clean so try cleaning both by taking on/off or use a small screwdriver.

Garybuz, thanks for taking the picture, really appreciate it. But i still cant see it in my polo!

Is it fixed in that position?

Edited 20 May, 200818 yr by s79

Right, having ordered a VAGCOM cable off ebay & recieving it today i got the following readout having just run it:

(unfortunatley its the shareware version of VAGCOM so I'm not sure that all the codes are being displayed? unless anyone knows better?)

********************************************************************************

VAG-COM Version: Release 409.1-US

Chassis Type: 6N - VW Polo

Scan: 01,02,03,08,15,17,19,25,35,41,45,46,55

-------------------------------------------------------------------------------

Address 01: Engine

Controller: 032 906 030 S

Component: MARELLI 1AV 2138

1 Fault Found:

00525 - Oxygen Sensor (G39)

07-10 - Signal too Low - Intermittent

Readiness: N/A

-------------------------------------------------------------------------------

Address 02: Auto Trans

Controller: 001 927 749 D

Component: AG4 Getriebe 001 0215

2 Faults Found:

00518 - Throttle Position Sensor (G69)

03-10 - No Signal - Intermittent

00545 - Shareware Version. To Decode all DTCs

31-00 - Please Register/Activate

-------------------------------------------------------------------------------

Skipping Address 15-Airbags

-------------------------------------------------------------------------------

Address 17: Instruments

Controller: 6N0 919 910 P

Component: KOMBIINSTRUMENT MMO V04

Coding: 00441

Shop #: WSC 00203

No fault code found.

*************************************************************************

What are your thoughts? I can explain the oxyegen sensor cus I'm the one that disconnected it! p.s. i tried the test with the ingnition on (obvioulsy) but without the engine running.

Seems not too much wrong. Reconnect lambda sensor. Clear all fault codes (DTCs).

Now give your throttle body a good clean and then perform throttle body alignment.

http://www.ross-tech.com/vag-com/cars/throttlebody.html

Drive around for a bit. See how car behaves. Rescan codes to see what comes up. You can also do live traces to see if the lambda is working properly. One step at a time, and you can beat the answer out of the car.

PoloD.

(I see you have an automatic)

For a list of VAG dtcs see: http://www.evvo.co.uk/forums/showthread.php?t=13542

and then you can decode all those that say "Shareware Version. To Decode all DTCs"

Edited 20 May, 200818 yr by PoloD

Just reread your post and I see that your thermostat housing is leaking coolant. Does your car get up to operating temperature ok and stay there no matter what? If not you need to replace the thermostat housing and pin.

Edited 20 May, 200818 yr by PoloD

Thanks for those tips PoloD

Just to let u know i reconnected the lambda sensor connector, but didnt get as far as running VAGCOM again & clearing the error codes! Will do that tommorow now.

I also gave the TB a proper clean out by taking it off last friday, so i dont think i need to do that again, just the TB alignment that u suggested. But can i perform the throttle body alignment using a shareware version of VAGCOM? What are the limitations of the shareware versions exactly?

Also yes my thermostat housing is leaking coolant, But it does get up to operating temperature ok and stay there.

Ok, well done. The 00545 dtc may be due to battery lead disconnect at some point. Did you do that? The other possiblity is the ECM power relay.

I think that after TBA, you'll be fine. Automatics are heavily reliant on the ECU to control the idle and are prone to drift due to dirt in the TB. I'm not sure if the shareware version can perform TBA or clear dtcs. I refer you to the ross-tech website to find this out.

PoloD.

WTF! I started the car this morning from a cold start and it didn't cut out straight away!!! Although it still isn't totally sorted as it still struggles somewhat when idling, and also if u rev it and then let the revs drop quickly. But all I did this morning was give it the merest amount of throttle and it stayed running! Touch wood but looks like were getting somewhere! :-D

But what's bugging me is that I'm not sure what I did to help it!!!! I did three things yesterday in the following order:

- Ran VAG COM for the first time

- Disconnected & reconnected the connectors to the black box immobiliser thing as suggested by garybuz - at least I think that's what it was cus the location & the connectors looked different to his pic!

- Reconnected the lambda/Oxygen sensor connector

Any ideas what might have helped? And any suggestions what might be the root cause now?

I noticed that after the reconnecting the lambda the engine ran a tad less smoothly?

PoloD, I know u looked at my VAG COM readout before, I noticed that u didn't think the Throttle Position Sensor error was particularly important? Did u mean to say that? I also get the feeling that that error has always been there.

About the 00545 error, yes I have disconnected the negative terminal of the battery several times, but what is the ECM power relay?

Anyway my next step will be to do the steps suggested by PoloD, i.e. Run VAGCOM again, clear the error codes & check the lambda is OK, and then try & do the throttle body alignment.

But can anyone give a definitive answer about whether I will be able to do the TB alignment & clear the error codes with the shareware version of VAGCOM? Also is the version available on ross-tech shareware or not? I am using the VAGCOM software that came with my cable.

If I do need the full version, is there one on the ol' interweb that works? (nudge,nudge,wink,wink)

And finally can VWTool do Throttle Body Alignment and set everything to default values or is it purely a diagnostic reading tool?

Edited 21 May, 200818 yr by s79

If this does not cure the problem, then I suggest you have a look at the spark plugs and give them a change. VW recommend an interval of 40,000 miles for changing them. But, they're not very expensive for that car - and buy good quality ones NGK or Bosch only. But missfire due to worn sparks or HT leads *usually* shows up on a OBD scan.

PoloD.

Oh FFS! Tried to fit the new spark plugs that I had bought a while ago, only to find out that they had a different type of cap so the ht lead connector didn't fit, that was after I put all four in! It seems the HT lead lead connector needs the to connect to the bare thread connector on the spark plug, but I couldn’t even unscrew the caps on these NGK's I bought?

Cus I got so hacked off (and cus the footy had started) I took the plugs out and left all the cylinders bar one without a any spark plugs in place. And I've just found out after speaking to a mate a work that that was a bad thing to do because of condensation in the cylinders! WTF!

So gonna have to back to the shop again for the third time & get the right plugs and fit them tonite...

Anyway I'm starting to get really pissed off with this whole thing now. And apologies for my lack of subtlety here but has anyone got a cracked / patched version of VAGCOM that works and that they can email me? Or at the very least the exact name of the torrent file of a cracked/patched version that works? I get the impression there are few that are a bit flakey.

Edited 22 May, 200818 yr by s79

Another update

New spark plugs haven't made a difference. Trying to get my head round getting VAGCOM to work so i can do the TB Alignment.

But in the meantime do u guys think the coolant temp sender is worth replacing, i get the impression when this plays up the car revs high rather than revving to low & struggling to start, am i right?

Well to just to update, my mums cursing was due to the fact that she got the car started on Tuesday morning but when she got down the road the revs shot up and/or got stuck & she nearly crashed the damn thing!

haha, my mums p plate 1.0 self accelerates from time to time, you can actually watch the pedal go down on it's own, spooky!!! haha!!!

Right, i think (touch wood!) i have sorted the starting problem!!!

Got a version of VAGCOM to register and i ran the throttle body alignment last night (very cool btw!) and then left it over night. Started it this morning and it started without the engine dying! :-D

But (there had to be a but didnt there!) I've got new problem!!! Now when idling, the revs drop momentarily for just a few milliseconds and it does this on regular cyclic pattern, say every 5-10 seconds or so. I had this same problem with the car about two years again, and spent months trying to get to the bottom of it,and i cant actually remember how the problem went away....

Anyway if you remember i mentioned that one of the many things i tried in the last week was to reconnect the lambda(oxygen) sensor connector after having it been left disconnected for over a year. So i thought as a test i would dissconnect the connector again while the engine was still running to see if that resolved it, and low & behold it starting running fine!!! So can i safely assume my actual lambda sensor is faulty then? Or is this a complete red herring and could the coolant temp sender be being mischievious again? How do i test if the lambda is faulty?

P.S. here is my most recent list of errors from VAGCOM autoscan

*******************************************************************

VAG-COM Version: Release 409.1-US

Chassis Type: 6N - VW Polo

Scan: 01,02,03,08,15,17,19,25,35,41,45,46,55

-------------------------------------------------------------------------------

Address 01: Engine

Controller: 032 906 030 S

Component: MARELLI 1AV 2138

No fault code found.

Readiness: N/A

-------------------------------------------------------------------------------

Address 02: Auto Trans

Controller: 001 927 749 D

Component: AG4 Getriebe 001 0215

2 Faults Found:

00518 - Throttle Position Sensor (G69)

03-10 - No Signal - Intermittent

00545 - Engine-Transmission Electrical Connection

31-00 - Open or Short to Ground

-------------------------------------------------------------------------------

End --------------------------------------------------------------------------------------------------

Edited 24 May, 200818 yr by s79

Another update - the lambda may have been a red herring after all because I've just found out the repeating jerky idle problem still occuring even tho the lambda connector is disconnected. Any thoughts anyone? Is the temp sender on its way out?

Edited 25 May, 200818 yr by s79