2000 Polo 6KV5 1.4 16v (APE) EML, Limp home mode, the works.

[Tony S]

Evening everybody ........ First post and as always ........ A cry for help.

A few weeks ago my Polo started throwing up an EML and going into limp hole mode.
I asked a mate of mine, who has a semi professional OBDII type code reader, to read the codes and see what's what.

Without going into too much detail, it showed problems with the immobilizer, EGR valve, Throttle body, Vehicle speed sensor and the ABS system.
I asked him to clear all the codes and I set about sorting everything out.

As a side note, the EML and limp home could sometimes and I mean only sometimes be overcome by continually starting and stopping the engine, then probably one in 20 tries, the engine would start normally and run OK.

So, I sorted out the ABS and VSS problem by correcting a deformity on the N/S front ABS reluctor ring ......... Tick ....... Job sorted.

I then removed and cleaned the TB and fitted a second hand EGR valve. After doing a lot of reading, I realised that I needed to have the TB adapted (I'm new to FBW throttle bodies) so I found a local VW independent garage in Norwich who have VAG-COM, but the TB adaptation cycle failed.
Back to the drawing board ....... After more reading, I then removed the EGR valve and all the associated pipework and thoroughly cleaned it all with TB/carb cleaner.
I had also learnt that the EGR had to be adapted and that the TB couldn't be adapted if there was a fault code present Doh !!!!

So, once again, everything was put back together, with new gaskets for either side of the EGR, EGR pipe work and just for good measure, another second hand TB, new TB aluminium gasket and a new sealing ring below the TB mounting plate were fitted, now with the intention of going back to the VW garage again.

By the way, I also checked all the electrical connections to the sensors, main loom connectors, connections to the engine ECU. Also checked all the earth points and main metal fuses from the battery.

But now, that car was running so badly, that it would only ever start in limp home mode, so impossible to drive to the garage. Or not even start at all; It would turn over but not fire.
Knowing that I was really stuck now, I asked around and finally got my hands on a fully registered VAG-COM from another friend of mine, who works for Lotus Engineering. Him and his mates at work, had all clubbed together to purchase the VAG-COM 6 years ago ............ Result.

So this afternoon , I was convinced that I would sort everything out and have the car running again. No such luck!!
I performed a full system interrogation for all the fault codes, which came up with loads of them, caused by trying to start the engine over and over again.
I then deleted all the DTC's and read the engine codes again. Basically it informed me that both the EGR valve and TB required adaptation.
When I tried the EGR valve adaptation (074) it failed. The TB also failed the adaptation process (060), I assume due to there being a fault code present.

So now I'm completely stumped ..........
I've replaced both the EGR and TB with second had units with exactly the same part numbers.
The EGR to TB metal pipework has been cleaned out.
The MAF (thrust) sensor was filthy with carbon, but was cleaned and replaced.
New gaskets have been fitted to the EGR and TB assembles.
All the possible wiring connectors have been checked, including the earth points.
Neither the EGR or TB will accept the adaptation procedure and the car now refuses to fire at all.

I'm now considering buying a new EGR valve, just as a last ditch attempt, as I've read that they are very unreliable.
I don't want to end up spending too much money, as the car is probably only worth about £500 - £750.

HELP ........... What can I try next !!!!


Thanks in advance.
Tony

Ps ...... Sorry for the extra long post, but I wanted to explain as much as I could.

[doctordubs]

It failed because it was second hand ****. Buy new tbody and egr. It should clear and adapt then

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[Tony S]

It failed because it was second hand ****. Buy new tbody and egr. It should clear and adapt then


Well, even though I did mention in my original post that the car was only worth £500 - £750 and I didn't want to spend too much on it. I did buy a brand new EGR valve, fitted it and attempted the adaptation.
Once again it failed!!!

So, new parts aren't always the answer......

Another question; when using a genuine and registered version of VAG-COM, what would cause an adaptation to fail? Especially if a new part has been fitted and it still fails.
I know that the TB can't be adapted if there's a fault code present, that's why I'm concentrating on the EGR first, as if I can't adapt that, I certainly won't be able to adapt the TB.

Petrol can and a box of matches at the ready ................

[Sam]

Welcome to VWAF :)

Everything you could ever want to know about performing a TBA is here;

Throttle Body Alignment (TBA) - Ross-Tech Wiki (http://wiki.ross-tech.com/wiki/index.php/Throttle_Body_Alignment_(TBA))

If you're able to get your hands on the VCDS again, run a full auto scan and post it up here, it's a bit tricky to guide you further without knowing what's going on with the car. Your descriptions are great, but fault codes speak louder than words...or something.

[Tony S]

Will do........ I'm currently re-charging the laptop.
Do you want only the codes, or full descriptions as well?

If I turn the engine over, in an attempt to start it (which it won't) it will then throw up a whole host of fault codes.
Anyway, once I have a chance, I'll post all the necessary information.


Many thanks for the offer of help.
Tony

[Tony S]

Welcome to VWAF :)

Everything you could ever want to know about performing a TBA is here;

Throttle Body Alignment (TBA) - Ross-Tech Wiki (http://wiki.ross-tech.com/wiki/index.php/Throttle_Body_Alignment_(TBA))

Thanks for the welcome.
I'd already found and read the above document, in fact I printed it as 'help sheets' during the attempted EGR and TB alignments.


More later .........

[Tony S]

Sorry about the delay in replying.
I help out at a local Hardware shop on Saturdays and Sunday mornings, then I had to help my two sons strip their old track car, before it goes off to the 'track in the sky'.

Anyway, the Polo's fault codes and miscellaneous information:

2000 Polo estate, 1.4 16v
Engine code: APE
Variant 6KV5
ECU: 6K0 906 034 C
VAG-COM (VCDS), release version used: 14.10
Battery voltage during code read: 12.4v


Full scan results on 01 Engine:

17989 Throttle Actuator (J338)
P1581 Basic setting not performed.

17812 EGR system
P1401 Basic setting not performed.

17847 Potentiometer for EGR (G212)
P1438 Error in basic setting.

17953 Throttle Valve Controller
P1545 Malfunction intermittent.

17848 EGR Valve (N18)
P1440 Open Circuit.

17953Throttle Valve Controller
P1545 Malfunction


The above codes were read, with both the original TB and EGR valve, also a second hand TB and EGR valve, and then a new EGR valve (at the insistence of doctorbubs).

The codes were then deleted, which left only two codes:

17989 Throttle Actuator (J338)
P1581 Basic setting not performed.

and

17812 EGR system
P1401 Basic setting not performed.


I then attempted to adapt, firstly the EGR valve ............ Error
Then adapt the TB ............... Error.


Finally, I attempted to start the car (it only turned over, without firing).
And a final auto scan, resulted in the same 5 fault codes as per the top of this post.

After chatting to my mate, who works for Lotus Engineering and is part owner of the VAG-COM, he suggested removing the [engine] ECU, which is situated under the windscreen scuttle, and try to open it up and check for any damage to the PCB.
I've already removed the ECU once, just to check for connector / pin damage and also to check for any possible connector corrosion.

That was when I opened up all the engine wiring loom connectors, also for damage or corrosion.
At the same time, all the earth points were checked.


I hope the above information is able to possibly pinpoint a possible cause.



Thanks in Advance.
Tony

[doctordubs]

Before anything im going to cross check the codes on my autodata wich gives detailed description of code and reasons. Although it seems to me as tho your cars issue is with the throttle pedal unit as it tells everything what to do and when. But il let u know tomorrow wat iv found. Il assist were I can until problems resolved. Its the least I can do

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[Rob69]

Going back to your original problem - EML and limp, have you done a compression test to check exhaust valves ?

[Tony S]

No I haven't Rob69, as I'm still convinced that it's an electrical problem.
Thanks for your input anyway.

Tony

[Tony S]

Although it seems to me as tho your cars issue is with the throttle pedal unit as it tells everything what to do and when.

Thanks doctordubs .......

I have to admit that I did stick my head into the driver's foot well, knowing that the TB was DBW, but had no Idea where the throttle pedal 'box of tricks' live.
I've no problem with checking that out, but I have absolutely no idea where the throttle 'gubbins' live. All I could see, was a rod running horizontally to the centre consul area.
I'm more used to conventional cars, with a throttle cable set-up.

Would you happen to have a general procedure, as how to locate the throttle potentiometer? If so, I'll give it a go at looking for and removing it.


Many thanks
Tony

[doctordubs]

Strip the cover off under the dash and follow the rod. The potentiometer is part of the pedal assembly and is housed in a plastic box bolted to the firewall.

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[Tony S]

Strip the cover off under the dash and follow the rod. The potentiometer is part of the pedal assembly and is housed in a plastic box bolted to the firewall.

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Thank you, I'll give it a go this afternoon.

By the way, I removed the engine ECU yesterday ........ My God!! What a stupid place to locate such an important piece of kit!!!
It came out, looking like a mouldy, furry piece of white cheese. After a few 'non standard' procedures (the 4 torx head screws were well and truly seized in place, plus the heads rusted away) I managed to take a look at the ECU PCB.
There has been some moisture ingress, as I can see some staining on some of the contact tracks, so I will pass that onto my mate at Lotus Engineering to take a look at under his microscope, and hopefully repair any possible damage.

A question ......... There's an loom earth wire attached to the ECU securing screw post. Does the ECU require an earth through the casing, or is it earthed via the two main wiring loom connections?
I ask because there's no way that with all the surface corrosion (steel mounting frame to aluminium ECU casing .... Doh!!) an earth would have been made.

In the meantime, I'll report back on the throttle pedal pot.


Tony

[doctordubs]

It definitely requires an earth. Corroded earths is a vag car problem. Id leave the pedal for the moment. If corrosion damage is clearly visible on the ecu its most likely the cause of all the problems. Whilst ur at it underneath the battery tray are 2 more important earths. Give them a clean and spray with tectyl afterwards to keep it clean and corrosion resistant. The ecu plug will need a good douse of electronic contact cleaner, not wd40 or the like, to remove all traces of corrosion

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[Tony S]

It definitely requires an earth. Corroded earths is a vag car problem. Id leave the pedal for the moment. If corrosion damage is clearly visible on the ecu its most likely the cause of all the problems. Whilst ur at it underneath the battery tray are 2 more important earths. Give them a clean and spray with tectyl afterwards to keep it clean and corrosion resistant. The ecu plug will need a good douse of electronic contact cleaner, not wd40 or the like, to remove all traces of corrosion

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Thanks doctordubs .........

I did locate the throttle pot, but I still need to remove another panel to be able to remove it and it's wiring, so as you say I'll leave it for the moment.

It's interesting regarding the ECU earth, as there was certainly no direct earth path from the ECU mounting stud, through the rusty ECU frame to the heavily corroded ECU case.
I can always give the frame and case a good wire brushing before re-assembly, to hopefully reinstate and ECU earth path.

By the way, my mate from Lotus Engineering took the ECU away this evening, for a close inspection of the PCB over the next few days.
One thing he did ask, was the pin I/O configuration from the ECU to the TB and EGR valve. I've checked through the Haynes book of bo**ocks and nothing is mentioned.

So, would anyone happen to have an engine wiring diagram, covering the ECU, TB and EGR valve, so I can trace the wiring and let my mate know the pin connectivity between the three components.

MY 2000 1.4 16v Polo estate
Varient: 6KV5.
Engine code: APE
ECU: 6K0 906 034 C
TB: 036 133 062 B
EGR: 036 131 503M


Thanks
Tony

[doctordubs]

Il email you a diagram. Just drop me the address Tony.
Btw my name is Nicholas. Glad to assist

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[Tony S]

Il email you a diagram. Just drop me the address Tony.
Btw my name is Nicholas. Glad to assist

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Nicholas, you should have a PM waiting in your 'in box', with my contact details.

By the way, many thanks for your amazing amount of assistance regarding this problem I'm encountering.


Tony

[Tony S]

Well, I've had to continue looking for this fault over the last few days, apart from a weekend break for the Silverstone Classic .......... Bl**dy rain !!!

So, the ECU PCB has been checked over and there seems to be no water damage or burned out components, so that's back in the car.
I did check ALL the earth points in the engine bay, and they all seemed fine but I cleaned them all anyway. Plus I made a definite earth path from the ECU case, to the mounting frame, to the mounting (and earth) stud.
All earth points (including the ECU) were checked using a multi-meter and all gave a reading of less that 1 Ohm, earth to earth, so I was happy with that.

I had to return the laptop and the VAG-COM to their respective owners, so all I could do in the meantime, was to try and start the car, which it did each and every time I tried it .......... But ......... It still will only run in limp home mode.

As soon as I get my hands back on the laptop and the VAG-COM, I'll try the testing and adaptation procedures again and report back.



Tony

[doctordubs]

It starts up every time wich is good. Im pretty sure that the adaptation is all Thats required to get it perfect again. Tony ur email adress is not accepting my mails?? Do u have another adress? ?

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[Tony S]

It starts up every time wich is good. Im pretty sure that the adaptation is all Thats required to get it perfect again. Tony ur email adress is not accepting my mails?? Do u have another adress? ?

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Nicholas, you have another PM.


Tony

[doctordubs]

Got it tony. Ul get the mail at about 18.00 hours C.A.T

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[Tony S]

Before anything im going to cross check the codes on my autodata wich gives detailed description of code and reasons.

Nicholas,

Were you ever able to perform an "autodata code cross check" to see what it throws up?
If so, maybe you could kindly include it with tonights e-mail.

[Tony S]

Well, I've been able to borrow the VAG-COM again this evening and immediately tried the EGR and TB adaptation .......... Once again failed on both counts!!!
I really don't know what to do now.

[doctordubs]

Ignition ONEngine OFFSystem voltage at least 11.0 V.[Select][01 - Engine][Basic Settings - 04]Group 063[Go!]Activate the Basic Setting.[ON/OFF/Next]Press the pedal to the floor and hold it their for at least 2 seconds.Observe Field 4, once the adaptation is successfully done it should show "ADP. O.K.".[Done, Go Back][Close Controller, Go Back - 06]Switch Ignition OFF.

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[doctordubs]

Try this. I think ur trying to adapt what isn't there. Im under the impression ur pedal assembly controls the lot

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[Tony S]

Will do Nicholas, I've never tried block 63, so anything for a possible success.

Another thing I've come across, after doing a lot more research ........
I don't seem to have a 12v feed for either the TB or EGR. So I could have a broken wire, bad connector, or blown use .......... Somewhere!!!

As I've mentioned before, I've already checked all the engine bay wiring harness connectors and all the fuses by the driver's right knee 'cubby hole' fuse box.

By the way, I never did receive the wiring diagrams on either e-mail address, so I'm still working in the dark.


Tony

[Tony S]

Well, I must update this thread ...........

After a lot more investigations and discussions with my mate from Lotus Engineering, he suspected that the ignition switch contact assembly might be faulty.
He thought this, as I finally managed to get my hands on a wiring diagram for my car and checked all the circuitry to the TB and EGR valve. It transpired that the TB is fed via the ECU and the EGR is fed via fuse No. 30
The feed to fuse No. 30 was only reading 10.2v and the output from the ECU (to the TB) was 9.4 volts. So that's what made him think that the feed from the ignition switch was at fault.
So I ordered a brand new and genuine VW ignition switch contact assembly (from Poland at £16 inc P&P) ......... So that's us up to date.

The ignition switch contact assembly arrived yesterday but I haven't yet been able to fit it, as I'm not able to remove the steering wheel and column as a complete item, as the UJ is welded to the bottom of the steering column and won't pass through the column support tube. That would have allowed a minute amount of access to reach the screw that holds the contact assembly in place.
So, as I can't remove the steering column, I'm going to have go through the tedious process of removing the air bag, steering wheel, indicator and wiper stalk / switch assembly, splined collar and ignition switch, just to access the contact assembly ................ Unless someone knows of an easier method ??

Anyway, this evening, just to test my theory, I plugged the ignition contact assembly into the wiring loom and put the ignition key into the lock (just to pacify the immobiliser circuit) then used a screwdriver to turn the contact assembly switch ................... Bingo .............. It started perfectly, with no EML or limp home symptoms and it revved normally.

So, one second hand TB, one second hand EGR and a brand new EGR, ECU removal and PCB inspection, plus almost 8 weeks of head scratching later, the problem has been solved by a £16 ignition switch assembly!!!



But As mentioned, I still have to install the blessed thing, so any hints or tips would be gratefully appreciated.

[Tony S]

Well, I must update this thread ...........

The ignition switch contact assembly arrived but I haven't yet been able to fit it, as I'm not able to remove the steering wheel and column as a complete item, as the UJ is welded to the bottom of the steering column and won't pass through the column support tube. That would have allowed a minute amount of access to reach the screw that holds the contact assembly in place.
So, as I can't remove the steering column, I'm going to have go through the tedious process of removing the air bag, steering wheel, indicator and wiper stalk / switch assembly, splined collar and ignition switch, just to access the contact assembly ................ Unless someone knows of an easier method ??


Anyway, this evening, just to test my theory, I plugged the ignition contact assembly into the wiring loom and put the ignition key into the lock (just to pacify the immobiliser circuit) then used a screwdriver to turn the contact assembly switch ................... Bingo .............. It started perfectly, with no EML or limp home symptoms and it revved normally.


So, one second hand TB, one second hand EGR and a brand new EGR, ECU removal and PCB inspection, plus almost 8 weeks of head scratching later, the problem has been solved by a £16 ignition switch assembly!!!



But As mentioned, I still have to install the blessed thing, so any hints or tips would be gratefully appreciated.

[Tony S]

Now installed and working as it should.
Thanks to all who helped me with this marathon fault finding exercise.

[doctordubs]

Wow....il put this in my never forget bank lol. Gee wizz tony. In my 10 years iv never known a ignition switch to cause this much problems. Maximum respect to you and ur mate at lotus

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[Tony S]

Wow....il put this in my never forget bank lol. Gee wizz tony. In my 10 years iv never known a ignition switch to cause this much problems. Maximum respect to you and ur mate at lotus

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If you look at it in hindsight (yes I know; it's a wonderful thing!).

Sometimes turning the ignition key and nothing ......... Ignition contacts.
Turning the engine on and sometimes going into 'limp home mode' ............... Ignition contacts.
Low voltage going through 'something' and onto the fuse box and the ECU ......... Ignition contacts.

All very logical now but at the time, a real nightmare.
I believe that I'll also remember this episode for a long time and keep it logged for future reference.

In fact if I were to be reimbursed the £50 for the new EGR valve I was 'persuaded' to purchase, that wasn't needed, it would increase the experience even more .........


Tony

[doctordubs]

Lol, im a good 17000 km away from you. U guys get parts cheap. Here in sa wed pay approx 5000 - 6000 ZAR for an egr valve.

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