GTI shutting down during normal driving

[jmcc]

Hey guys,

My GTI ran into some trouble, its still stock at the moment, I was driving locally when the car seemed to hesitate and then completely shut down. I called the NRMA but after half an hour of waiting I decided to give it another whirl and it started.

I thought maybe there was a bit of a hickup in the fueling but couldnt find any codes and it drove normally for a month, then I was driving on the highway the other week and happened over again. The engine stumbles for a second, and then shuts down completely. This time I decided to give it a go every 10 mins to see what happened and after about 40 mins it started again and drove home without a hitch.

I took it my mechanic and he couldn't find any obvious issues and suggested the fuel pump as the most likely culprit given it's tendancy to come back to life. Fuel pump swapped and test driven for 40 mins with no issue, then I went and drove it for about 30 mins an hour later and the same issue. I was in a precarious spot so I called for a tow straight away but it still wasn't starting when it got picked up so it's possible whatever it was died completely, but I get the feeling it will start when it gets looked at tomorrow.

My best description of the circumstances and symptoms are;
- Happens at normal operating temperature
- Usually happens after a bit of driving even in one stint of if the engine hasn't cooled between drives
- Issue seems to usually occur under load and part throttle, most of the time I've been going up a gradual incline.
- The car will drive normally up until the issue arises usually no prior indication that something is going wrong
- The car stumbles/bucks before shutdown maybe misfiring on one or more cylinders (kind of the feeling you get when an auto can't decide on a gear)
- Starter motor turns over fine afterward
- Engine doesn't pick up at all afterward
- After a while it might give a bit of a gurgle like its going to start but doesnt quite make it
- I noticed on the last shutdown the accelerator peddle moving slightly underfoot as the engine stumbled, a slight reduction in pressure and then a slight increase against my foot back and forth a few times.
- Pulled a coil off and had spark on cylinder one, car started before I checked the others


Car has now (syptoms have occured before and after all these changes);
A new fuel pump
NGK BKR7E with less than 1000km on them all properly gaped
replaced vacuum lines to the FPR and brake booster
Replaced thermostat and fully bled and replaced coolant, no signs of oil
Oil change <1000km ago, oil flowed well, no sludge, chunks or signs of coolant contamination
cleaned MAF with MAF cleaner, no obvious damage or corrosion

The oil leak issue from previous posts is still a mystery, degreased the engine bay and as yet haven't noticed any build up, though I'm yet to completely pull apart the intake system.

Is it possible for this car to vapor lock? its not exactly cool in the engine bay on a hot day even around the intake side. Other possibilities I'm looking at are maybe a crank position sensor? though I'm not sure it would be affected by temperature. or possibly a relay on it's way out?

Sorry for the wall of text, not sure where to go from here since I'm not getting any codes and so far all my mechanic and I can think of is replacing things until it's fixed, and since it's a pretty unpredictable problem it's hard to know if it is fixed.

Thanks!

[Sirocco20348]

I have had those symptoms with no codes before under 2 situations. First was my throttle body. Let me find a thread for you.

https://r.tapatalk.com/shareLink?url...4&share_type=t

2nd was my maf and icm

https://r.tapatalk.com/shareLink?url...4&share_type=t

I should update that thread more to say I changed my maf aswell.

I am leaning towards your maf and icm being stuffed because that situation for me shut the car down.

[jmcc]

Hey, thanks for the links!
I'm the 2nd one where you said you got a "wrx exhaust note" what did you mean? I tried to look it up but couldn't find anything.

[Sirocco20348]

When the ICM starts to fail, your car starts to sound like a mild boxer engine accustomed to a wrx with an exhaust.

In that thread, the ECM was changed first due to the sound my car was making and that made things better to begin with.

But ultimately my maf was stuffed. It continually got worse until it fully died on me in a cloud of smoke. When I mean worse, the car would continually go into limp mode. I diagnosed it by unplugging the maf and the car drove fine. Bought a new maf and problem solved.

I had also tried to clean the maf etc, but with 200k on the part, I thought it was time to buy a new one. It was around $300 for genuine VW maf. Don't buy aftermarket!

Sent from my Nexus 5 using Tapatalk

[DAM GTi]

^^
beat me to it..if a CAT has been done to it- though gavin has also said to reseat the fuel pump!

looking into a ICM delete (AGU- AUM Ignition coil mod)next day off over this way-yet it has been stated that wacking it on a large heat sink is more than enough-see how Im feeling!

[jmcc]

Hey guys!
So I went back through all the previous owner's repair receipts and the MAF had been replaced genuine last year, I followed a guide for testing the ICM and couldn't find any issues.. Mechanic said it's most likely the crank or cam angle sensor by the other symptoms so just went ahead and replaced both.. Car seems to be running great now!

I'll update if there's anymore drama incase others come across this when their car isn't working

[JustCruisn]

Have you had a proper vcds scan done on the car ?

Another common failure is the cam/hall sensor. I had this fail twice on me over the years. When it goes it will not start then after a while it will run again for a random amount, again I thought it was a fuel issue. A scan pointed it out instantly, cheap fit too like sub $80.

[jmcc]

Na the only place nearby with vcds was $$$$ I replaced the cam sensors aswell as the crank for the same reason.. I think I might get one of those budget scanners

[Sirocco20348]

Na the only place nearby with vcds was $$$$ I replaced the cam sensors aswell as the crank for the same reason.. I think I might get one of those budget scanners

You will find a shop that will scan you for free, it takes them a grand total of 2 minutes to run. I can't believe they are charging you at all? Just buy a China cable. Or keep asking around here, someone will help you out. I would buy I'm in Brisbane.

[Umai Naa!!]

Don't need VCDS specifically, to scan these. Just any decent OBD scanner really.

But yeah, totally sounded like it needed a crankshaft position sensor.