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No start and no OBD!


MB1
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Hi all,

Searched around the forums and found so much useful advice to help me check various things before getting to this point, so thank you!

 

I've got a 2000 1.0 MPI Lupo (unsure of any specifics past that) that cranks, splutters for maybe 1 second, then cuts out. It was sat for a few weeks and had been perfect up until that point, but suddenly (the week of its MOT, classic) it just refused to start.

 

I've checked fuel and spark and they're good, so went to check OBD...

Nothing. Voltage at the socket but no comm. Tried with a few known good devices that had worked with it before but no luck.

Things I've checked that appear fine:

- all fuses (in cabin and on battery)

- relays behind the cabin fusebox 

- fuel pressure to engine

- spark from all four plugs

- jump start just in case

- ECU connections are tight and clean

- wiggled ignition barrel, tried all keys, held key against barrel in case it's an immobiliser/key issue, etc

 

I've stumped two garages that took a look at it, so now I'm coming to the pros!

Where might I look next? Any ideas?

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Update on this, we've thrown so much money at it that we're cutting our losses and breaking it. Shame because it's a lovely car but we want it off the drive.

How's the market for standard Lupos like this one? Is breaking the best option or should we just scrap it?

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Weston-super-Mare. Y reg, 1.0l MPI (999cc) 6X, 66k miles on the clock, even got the original manuals from purchase etc. Can give further details upon request but not entirely sure of all the variations, this is my first Lupo (but not my last!) Could be an easy fix for somebody who knows what they're doing but after the third guy came and was just as stumped yet again, we're sick of it!

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It sounds a bit like immobiliser lock out... have you tried swapping keys to start it? I have once encountered a broken key transponder chip which gave the same symptoms (but the key symbol in the dash lit up telling me it was "lock out"). I love solving problems like this for free! Wish you were nearer to Reading.

If you get no OBD comms, it could be the ignition switch (very common problem). The dash and radio etc all light up? Headlights working? 

It'd be daft to break a perfectly good little motor, just because of a simple starting fault. 

With that milage and an MOT, I'd say worth perhaps as much as £1k if in very good condition.

Ah, had another idea- fuel pump or relay? Late edit- no, you checked that..

edit- crank sensor or loose wire, as it wouldn't fire at all if completely gone.

Edited by mk2
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38 minutes ago, mk2 said:

It sounds a bit like immobiliser lock out... have you tried swapping keys to start it? I have once encountered a broken key transponder chip which gave the same symptoms (but the key symbol in the dash lit up telling me it was "lock out"). I love solving problems like this for free! Wish you were nearer to Reading.

If you get no OBD comms, it could be the ignition switch (very common problem). The dash and radio etc all light up? Headlights working? 

It'd be daft to break a perfectly good little motor, just because of a simple starting fault. 

With that milage and an MOT, I'd say worth perhaps as much as £1k if in very good condition.

Ah, had another idea- fuel pump or relay? Late edit- no, you checked that..

edit- crank sensor or loose wire, as it wouldn't fire at all if completely gone.

Hey Mk2,

Really appreciate your thoughts here! It's actually my Dad's car that we've both shared for a few years, and I think he's just sick of it right now and listens to everything "mechanics" tell him so fears a gigantic bill 😂 but I'm still willing to try and get it started again and save it since I love the little thing! Would hate to take a Lupo off the road.

I've taken a video to show it "not starting" - it's not a clean non-start like I've seen with crank sensors before, more of a spluttery sadness. I thought either fuel or spark based on the fact it actually seems to fire up for a moment, but having checked both I'm stumped: 

So, keys - we have two. One turns the ignition, one opens the door. Not sure if that's due to ignition switch being changed before we got the car, or if it was just broken into or whatever, but we only have one key that's ever worked to start it. I did strip the steering column down to check for anything loose/disconnected/burnt but all looked fine. Headlights, radio etc work fine. How might we "test" the key/barrel as working?

I'm not one of those people who say "it's the ECU" because in my experience 99% of the time it's not, but... it's starting to look a little bit like that. Would love your thoughts!

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If it starts and sputters, not the ECU. It's certainly something simple. And electric. Not a mechanical problem if it was running fine up till a while ago, then just suddenly didn't want to start. 

Do you get the instrument cluster, "everything light up" at power on? - can you see the immobiliser lamp, usually yellow from memory? It's a key symbol.

I can't remember if on early Lupos vdub programmed into the cluster "light up immobiliser as well as all the other warning lights", or only the others just to show if they're all working. Anyone else know this off the top of their head? @Skezza @Rich???

I'd rule out plugs, injectors, throttle body, crank sensor (I don't think you have a cam sensor?). My guess is it's fuel related (if it's not the immobiliser). Either the engine is being starved of fuel or the ECU is pulling fuel (shorter injection pulses). Sounds like fuel starvation.

Wild guess mode... Temp sensor? If only you could get the k line interface going on the OBD, then you could check everything. Unusual. I'm trying to think what stops the OBD from working, if the ECU still runs ok. With only ignition on, definitely no comms?

Headlights stay on ok when ignition is on? I'm still thinking check ig switch...

Edited by mk2
Idea...
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That's the immobilizer cutting out, no comms on OBD... Diagnosis? You've @mattarosa'd it. I've currently got his old ECU and immo sat on my workbench that I'm going to try and get round to looking at in the next week or so.

Basically, you've lost your key coding. Stop getting mechanics in, for God's sake. They'll replace every part on the car before getting to that answer above. You'll get your best answers from here anyway.

Take your ECU out and find an IMMO OFF ECU on eBay (use the part number if you're struggling). You may have to wait a bit for one to appear. I think Matt paid 90 quid for his. Fit it. Drive and be happy. There are services offering IMMO OFF as well, you could always send it to one of those but I can't vouch for their ability and ECUs can be kind of delicate so it's your risk.

Your old ECU is now locked out though (basically, no key will unlock the security access code) and will need someone to extract the SKC by either desoldering the EEPROM or using a set of clips, so you can adapt your keys again or IMMO OFF it. I've not got round you doing Matt's yet... Soon though, soon.

@mk2 there is no immobilizer lamp on Lupos. There isn't even an EML on this 2000 model mate. The immo fault code will be logged but he won't be able to access it because the key is locked out.

Edit:

By the way, with yours and Matts, I only have a sample set of two vehicles so my research on this isn't brilliant but I spent some investigating the Polo from the same era. The only cause that I've been able to determine from research on how the EEPROM acts is that a voltage sag caused an EEPROM corruption in RW memory (you said it was left for a while), but it's only a hypothesis at the moment and the fact it seems to happen so infrequently means I don't think I'll ever know for sure.

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Thanks for all the responses! Genuinely appreciate it.

 

@mk2 Everything on the dash lights up, headlights stay on fine when wiggling the key, etc... With only the ignition on, definitely no comms. We've got lots of fuel up to the injectors but could very well be ECU pulling fuel. Still worth me going through and double checking (or even disconnecting) connections for various sensors just in case one's causing a short. I've had that knock out OBD comms before on other cars. Easy and quick job at least.

 

@Skezza What you're saying makes sense. Would IMMO OFF invalidate our insurance? Simple enough to just update and say "no immobiliser" and pay any extra premiums etc?

To increase the accuracy of your sample set, this Lupo had been parked on the road with the battery repeatedly draining itself down, requiring jump starts and battery recharges etc... So your theory makes a lot of sense. Hadn't really considered just how often this would have been happening, my Dad would have been repeating this cycle many times over the past 12 months since the car has barely been used over lockdown.

 

@Rich Thanks for your input - having another person say the same thing really helps. It's all starting to add up now.

 

I'll do my due diligence on the few remaining bits then just sort the IMMO OFF thing. Hopefully we can get it running again and off my Dad's drive before he gets sick of it and it becomes bean tins.

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https://www.ebay.co.uk/itm/Vw-Lupo-1-0-ECU-Kit-Black-Box-Key-chip-Induction-ring-030906032CP-2004/324141637763?hash=item4b7858e083:g:zKUAAOSw~8Ffxlp0

This matches the part number on the ECU and looks a cheap way of getting it at least running again - would something like this do the trick? (Obviously more work but immediately available...)

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If we all think it's immob lock out, and the car worked fine before, it "might" simply be that the transponder pickup ring is just not getting a high enough signal. If you're VERY careful, you can GENTLY prize out the rice grain transponder chip from inside the key and physically hold inside the transponder ring. If that doesn't get you a signal, then it might be worth going down the route of either a replacement key (from vdub) or what @Skezza suggests. 

The trouble is, that we still don't know 100% certain that it is the immobiliser, so it could end up being money spent for nothing.

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Yeah, very true. Good thought on moving the transponder closer to the inductor ring. May be safer to move the induction ring closer to the key but depends how many wires are on it...

My only thought re immobiliser is why would it crank and "run" for a few seconds if the immobiliser is kicking in? Does the immobiliser only pull fuel upon ignition or what? Not doubting your experience, just not what I've seen in the past with other cars.

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The immob ECU program is odd... Vdub will allow you to start the engine, then switch off a couple of seconds later. To me it makes much more sense to simply show a symbol on the dash when you turn the key to start it, or just switch on.

Yeah you could try simply taping the chip to the inside of the pickup ring. There are two types- one's a glass type, exactly the same as used in pet ID things, the other a a little plastic encapsulated one. Be careful if you have the glass type as they're super fragile.

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14 minutes ago, mk2 said:

The immob ECU program is odd... Vdub will allow you to start the engine, then switch off a couple of seconds later. To me it makes much more sense to simply show a symbol on the dash when you turn the key to start it, or just switch on.

Yeah you could try simply taping the chip to the inside of the pickup ring. There are two types- one's a glass type, exactly the same as used in pet ID things, the other a a little plastic encapsulated one. Be careful if you have the glass type as they're super fragile.

Really don't fancy smashing it! I'll take a very careful look...

Okay, so, maybe a game changer: my Dad now tells me he's unplugged the stock radio a few months ago before this happened. I swear I heard the CD player spinning up while I was working on it but I guess that's separately powered.

Is there a chance that unplugging the radio (and just leaving the plug unterminated) could cause K-Line issues meaning no OBD? Google sort of leads to that point but would rather just query those in the know.

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2 hours ago, MB1 said:

Thanks for all the responses! Genuinely appreciate it.

@Skezza What you're saying makes sense. Would IMMO OFF invalidate our insurance? Simple enough to just update and say "no immobiliser" and pay any extra premiums etc?

To increase the accuracy of your sample set, this Lupo had been parked on the road with the battery repeatedly draining itself down, requiring jump starts and battery recharges etc... So your theory makes a lot of sense. Hadn't really considered just how often this would have been happening, my Dad would have been repeating this cycle many times over the past 12 months since the car has barely been used over lockdown.

 

It might, but it doesn't have to be permanent. You could get the SKC extracted and re-pair your key (+ an extra one) with a cheap cable off the Internet.

I'd take it as a temporary solution while you get your ECU sorted. I haven't identified the conditions that the EEPROM becomes corrupted. It could be while the car is standing and trickling the battery, but it could be when you first start it after a long period and there is an immediate voltage drop, especially if the battery isn't quite as strong as it once was. It only takes one hit and the EEPROM is fubar'd. The ROM part of the EEPROM is probably fine and if you can get the SKC extracted and keys re-matched, the various values will be re-written within a few minutes of driving the car again.

Starting with an almost dead battery isn't good for the electronic components and this isn't just a VW thing.

2 hours ago, mk2 said:

If we all think it's immob lock out, and the car worked fine before, it "might" simply be that the transponder pickup ring is just not getting a high enough signal. If you're VERY careful, you can GENTLY prize out the rice grain transponder chip from inside the key and physically hold inside the transponder ring. If that doesn't get you a signal, then it might be worth going down the route of either a replacement key (from vdub) or what @Skezza suggests. 

The trouble is, that we still don't know 100% certain that it is the immobiliser, so it could end up being money spent for nothing.

I wouldn't bother. How often have you heard of an immo problem being solved by replacing the transponder pickup ring? I say that, I spotted your post from 2015 about transponder pickup ring failing on your Lupo SDI? I've never heard of one failing and considering the relative simplicity of the part, can't understand why it would.

I assume you've already tried jumping it with another car attached? It didn't sound as though there were any battery problems in the video above.

I'm 95% confident that my solution is going to get it off the drive in the short term. The issue you've got is that we don't know which end of your immobilizer system is goosed. However in either case, you're going to need to take your ECU out as you don't have your SKC. How are you going to re-pair your immo?

IMMO OFF mate, trust me.

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I wouldn't mess on with emulators, I would find someone clever with the vagcom and get the ECU de immob.

I like changing engines in cars and this is the route I take.

Less likely to bite you in the arse.

 

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Cheers for all the advice guys. Hugely appreciated.

I've got a mate down the road from me who can remove the immo stuff from the ECU today so we'll see how that goes. Had no idea this could be done so appreciate you leading me to this point.

The radio and CD player are stock VW ones that came with the car, sadly reconnecting the radio (the CD player was still connected) didn't change anything. No idea why my Dad disconnected it, how will he play his cassette tapes now???

Would be great if we can get this thing back on the road! I'll let you know my progress.

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Didn't get chance to reply. Radio is a red herring. The immobilizer uses KLine to communicate via OBD, but it uses W-line/W-wire to communicate with ECU.

If your Kline was dead, the car would still work fine.

IMMO OFF...

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Really quick update while I'm at work - immo off solved it. Thank you guys so much for your advice and guidance! You've saved a little Lupo and I'm thrilled! 💪😀

Will finish the job off and look further into additional/new keys etc later but just wanted to thank you all.

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2 hours ago, MB1 said:

Really quick update while I'm at work - immo off solved it. Thank you guys so much for your advice and guidance! You've saved a little Lupo and I'm thrilled! 💪😀

Will finish the job off and look further into additional/new keys etc later but just wanted to thank you all.

Did you send your locked out ECU to a service? Or buy an already IMMO OFF ECU? I'll be getting down to business with Matts this week. I'll document the process for reference. 

Once you've got your SKC, adapting new keys is trivially easy. I've done it on Audi A4s. Believe it or not, this whole process is easier on Audis of the same era because their ECUs are less secure. The separate IMMO boxes in these Lupos are a nightmare.

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