Diesel Engine Runaway 1.6 TDI POLO

[Finchley]

Hi Grizzly

My daughter was driving a 2011 Polo TDI on the M3 motorway in Melbourne when it spontaneously accelerated to a speed of 130km/hr despite trying to break it. Fortunately the engine blew up and she was able to bring the car to stop safely on the side of the motorway. This event took place in July this year.

We had the car taken to Doncaster Volkswagen which diagnosed it as a case of diesel runaway or diesel run on and told us the car had been over-oiled. We have not put any oil in it. The car is a write off but fortunately my daughter is safe but remains traumatised.

Im interested to read that your service technician advised that an ECU upgrade was part of the fix. Are you able to provide any more details on the fix or what caused your event? Have you had any problems with the car since?

I would love to hear from you or anyone else who has experience diesel run-on or diesel run-away, which may be rare fault but is incredibly dangerous.

[Transporter]

Welcome to the forum Finchley.
You most likely not get the respond from Grizzly, the last time he logged in was in 2014.

In no way by the text bellow I’m having a go at you, just trying to help you in the future to void a similar situation again.

ECU upgrade or not.
Here is what possibly went wrong with your daughter’s TDI Polo.
Someone during service put too much oil in the engine, but my experience is the the car owners often don’t check the oil level properly and then when topping it up, they put way too much of engine oil in, like 2-3 or even 4L of oil. Of course, when they recheck the oil level on dipstick it seems to be just about right, because the car was parked on uphill and they happily drive of and for very long time without checking the oil level, until something goes wrong. Bummer yeah?

The most likely runaway in your case, in many cases could be prevented (it wouldn’t happen) if the car owners check the oil level as they should, once a week, every 500km or when refueling. Also, there the flap in the throatle body which should stop the runaway diesel engine, it is the only purpose of that flap to be there and if it wasn’t working, someone didn’t do his job properly while servicing your daughter’s car, hence the importance of proper servicing by qualified mechanic and not DIY or back yarder self educated by Mr Google.

Of course they could also be leaking injector(s), but the check engine would come on and again the driver would see the increased oil level 500km later when checking the engine oil level.

[Finchley]

Welcome to the forum Finchley.
You most likely not get the respond from Grizzly, the last time he logged in was in 2014.

In no way by the text bellow I’m having a go at you, just trying to help you in the future to void a similar situation again.

ECU upgrade or not.
Here is what possibly went wrong with your daughter’s TDI Polo.
Someone during service put too much oil in the engine, but my experience is the the car owners often don’t check the oil level properly and then when topping it up, they put way too much of engine oil in, like 2-3 or even 4L of oil. Of course, when they recheck the oil level on dipstick it seems to be just about right, because the car was parked on uphill and they happily drive of and for very long time without checking the oil level, until something goes wrong. Bummer yeah?

The most likely runaway in your case, in many cases could be prevented (it wouldn’t happen) if the car owners check the oil level as they should, once a week, every 500km or when refueling. Also, there the flap in the throatle body which should stop the runaway diesel engine, it is the only purpose of that flap to be there and if it wasn’t working, someone didn’t do his job properly while servicing your daughter’s car, hence the importance of proper servicing by qualified mechanic and not DIY or back yarder self educated by Mr Google.

Of course they could also be leaking injector(s), but the check engine would come on and again the driver would see the increased oil level 500km later when checking the engine oil level.

Hi Transporter, thanks for your reply.

We always have our cars serviced in accordance with the log books but I never check oil between services unless the oil light comes on. My daughter would struggle to open the bonnet let alone know how to check and add oil to the engine. The last service the car had was at a Volkswagen dealer.

She said a light had come on. It was the DPF light.

Any idea on the ECU upgrade that Grizzy mentioned in his post?

Would you be able to send grizzy my email and ask him to contact me?

Thanks for your help.

[Rebuild]

Welcome to the forum Finchley.
Also, there the flap in the throatle body which should stop the runaway diesel engine, it is the only purpose of that flap to be there.

i always thought it's an anti shudder valve, to stop the engine knocking when you switch off.

Finchley, you can try Private Messaging Grizz. Left click his user name and select PM

[bloödstorm]

Scary story, Finchley. I suggest it may have undergone an excessive number of active DPF regenerations. Each regeneration lets a small amount of diesel into the crankcase, diluting the oil and increasing its level, leading eventually to the situation Transporter described with overfilled oil. The DPF statistics can be read via OBD.

[Transporter]

i always thought it's an anti shudder valve, to stop the engine knocking when you switch off.

Finchley, you can try Private Messaging Grizz. Left click his user name and select PM

So, where is the antishudder valve located?

Sent from my SM-N950F using Tapatalk

[Grizzy]

G'day gents.

Strewth, it's been some time since I have been on here! Cheers for the private message Finchley. I wouldn't have even responded if it wasn't for the email I received. I don't own the Polo anymore. Caused me way too much grief! Im sorry to hear about your daughter too, It's a horrible experience.

In the years after I started this thread, I grew older, wiser, and more pissed off with VW. The polo turned into a money pit I couldn't afford. If you have a Diesel with a DPF here are some things I learnt along the way (P.S. - Im in no way a professional when it comes to cars, engines, diesels, DPF's and so forth. However I figure some of this may help other 'Rookies' like I was)

1. Servicing is obviously always important. However with a diesel running a DPF I would be ever so strict (almost to the day) with your service intervals. When my Polo ran-away I was a few months over due, with a fair amount of short trips driven within that period. From memory.

2. The ECU flash performed was a load of garbage, as it had nothing to do with the issue. My Polo ended up being in and out of Volkswagen for the same type of issues for years after.

3. The issues appear to stem from the sump filling up with unburnt fuel (a knock on effect of the DPF regen), leading to the level of the oil in the sump rising and it's dilution. In effect giving the engine a better opportunity to start burning all the additional fuel sitting in your sump! Creating a run-away like scenario. My suggestion is to increase your knowledge and insist on keeping/checking a correct oil level.

4. Volkswagen should be scheduling servicing every 6 months in my opinion. Not every 12. It is my belief that this would keep the oil level and its dilution in check. Keeping the every day commuter much safer!

5. Driving around town in 3rd gear was probably the best discovery I made. With the higher RPM in the lower gears I found the DPF was getting hotter quicker (within standard regen intervals). Creating what I believe was better conditions for a standard regen.

In summary for those that may be thinking "he just hasn't looked after his car". After spending endless amounts of money, It turned out my injectors were firing out of spec. Meaning not only was unburnt fuel accumulating in the sump from the DPF, it was flowing unburnt through the cylinders too. Creating one big cluster f*ck of diesel swimming around in the bottom of my engine block! I also had a faulty EGR valve that was circulating too much recycled exhaust, which I believe added to the drama.

I hope this helps anyone who has been in a position like myself and hope no one has to deal with anything like it. Mods, please feel free to correct me with your knowledge base regarding any of my rant above.

Finchley, flick me another private message if you still want a chin-wag.

Cheers dudes!
Grizzy

[Finchley]

Thank you everyone for your posts, which have all been very helpful.

Our troubles started after the Polo was returned to Volkswagen for the so called diesel fix in March last year, when we had the scheduled service done at the same time.

Late last year the car started going into ‘limp mode’. The problem was diagnosed as a faulty EGR valve. My research found that in Europe this EGR valve problem was being linked to the ‘diesel fix’. In that case Volkswagen was excellent and replaced the valve at no cost to me. The whole EGR valve problem alerted to me the need for diesels to have regular runs at speed to allow the regeneration process to clean the DPF. I encouraged my daughter to regularly take the car for a good run to prevent the DPF from sooting up. Generally, she only putts around the city at low speeds. It was on one of these runs on the motorway when the car spontaneously accerated and blew up.

Volkwagen’s diagnosis is that the engine was over-oiled. We have never put oil in the car. Also, the dealer that replaced the EGR valve said they always check oil levels before cars go out of the workshop, which was in January this year. The incident happened in July, 6 or 7 months after coming out of a Volkswagen workshop.

I have been a rusted on Volkswagen supporter for many years. I’ve had 6 and have always had a Volkswagen in the garage since 1996. Volkswagen make beautiful cars however it is important to respond appropriately when things do go wrong. An appropriate response would be a proper investigation to determine the true cause of a malfunction (albeit rare). In my case I believe Volkswagen has swept this aside too quickly and not taken the time and effort to ensure there is not a wider safety issue.

Should anyone else have a similar experience with a diesel Polo or any Volkswagen diesel for that matter then I would welcome them to contact me by left clicking on my user name and sending me a Private Message.

Best regards everyone

Finchley

[Transporter]

I’d be really interested (most likely not possible now) to see the data scan from the ECU immediately after the engine runaway.
A lot can be interrogated from the ECU, like number of requests for regeneration, distance driven with check engine light “on” and heaps more to help to diagnose the root cause of the fault.
I’m not saying that your daughter didn’t take your advice seriously and kept driving short city trips for 6-7months leadings to failure, but it wouldn’t surprise me if it was a case and it’s also possible that the injectors were faulty and diesel leaked into the sump raising the oil level causing engine runaway.

Though from my decades of experience a lot of drivers just keep going when the check engine light is on for many weeks, months. There are some posts in the forums that indicate just that and keep in mind that only a few will admit that they didn’t seek the workshop ASAP.

I always like asking after I scan the ecu the question “...and when exactly that Check Engine Light came on?” ...and it’s really rare that the customer and ECU agree.

[Finchley]

Hi Transporter

They are all sensible and reasonable questions to ask. The dealership did not ask any of those questions when they did the diagnosis. The only thing they asked was 'did I put oil in the engine' to which my answer was no. The dealership has now given me photos of the engine and a 'self-diagnosis report' after the fault code was cleared. I have asked for the report before the fault code was cleared however, they will not provide it.

If you are willing to look at this information, please send me a private message with your email address and I'll send it to you.

I really just want to get to the bottom of what caused this incident. If we did something wrong or didn't do something we should have, we just need to know so we can close this out and move on. All we know now is that 'over-oiling' caused the diesel run on however we need to know how the car became over-oiled.