[stallingI30]

Hi all,

I have a 1.6 turbo diesel i30 (MY09) 4 speed automatic. I've owned the car since new and it now has ~135,000kms on the clock. The car has always been serviced on time by reputable mechanics. The car runs very well in all respects, good fuel economy, not burning oil etc. I'm typically a very conservative driver and don't give the car a hard time.

I'm experiencing a reproducible problem where the car will stall after the transition from medium-hard acceleration (up to ~3500rpm) and suddenly removing my foot from the accelerator.

This problem typically occurs when accelerating from a stop, and does not require full throttle to occur. After the car stalls, it takes 3 - 4 separate attempts to restart the engine.

I haven't been able to reproduce the problem if the transmission shifts into the next gear up before I remove my foot from the accelerator, although I'm not 100% sure this is the case.

I've already tried the following things, none have had any effects:

-injector cleaner (at every service)
-fuel filter (always appears clean at every change, last changed at 120,000kms, problem occurred before and after filter change)
-disconnecting the battery for ~30 mins, had no discernible effect.
 
I haven't yet taken the car to the dealership as they've been largely unhelpful with other minor issues. I'm concerned as it's a potential safety hazard, especially since it's an automatic and I must come to a complete stop and put the transmission in park/neutral before the engine can be restarted. I've Googled the issue/symptoms but have been unable to find anything relevant. If anyone has had the same problem please let me know.

[Shambles]

It would be interesting to see if you're getting a trouble code (DTC) logged.

Do you have access to an OBD2 dongle, or a friend who can read any codes off?

[Dazzler]

Welcome,

I was going to suggest a fuel or fuel filter issue, however, you appear to have covered that option.

Could be still part of the fuel system though, I suppose (like air getting in somewhere maybe)

Hopefully the dealer will surprise us all (for a change) 

[Doggie 1]

Welcome to the forum.
As much as you steer clear of dealerships (and I understand that), it might be worth considering to see what they come up with.

[Just Rick]

I had the same problem with Cyril,just before the stalling the revs would be limited to 3000 rpm,but after accelerating to that and then backing off He would stall,I would have to try one two or three times before he would start again,I am pretty sure from memory it was a faulty air fuel mixture sensor,once replaced it has never been an issue to date again

[stallingI30]

It would be interesting to see if you're getting a trouble code (DTC) logged.

Do you have access to an OBD2 dongle, or a friend who can read any codes off?

Yes, I had access to my son's cheap eBay Bluetooth OBD II dongle and Torque for Android app. We scanned for codes and no error codes were returned. He then took me for a very short drive as the passenger to see live sensor readouts as a novelty. Immediately, the transmission shifts (both up and down) were very harsh and audible. We stopped after 100 meters or less, disconnected the OBD II device and the transmission behaved normally, and thankfully no damage appears to have been done. He's since discarded the device!

Irrespective, the problem of stalling is the same before and after this event.

[stallingI30]

I had the same problem with Cyril,just before the stalling the revs would be limited to 3000 rpm,but after accelerating to that and then backing off He would stall,I would have to try one two or three times before he would start again,I am pretty sure from memory it was a faulty air fuel mixture sensor,once replaced it has never been an issue to date again

I had a look at the air fuel sensor (the one immediately prior to the inlet manifold, I'm not sure if this is a mass airflow sensor). The sensor had a thick layer of black oily gooey deposits which I cleaned off. This didn't have any effect either... the problem remains.

[stallingI30]

Welcome to the forum.
As much as you steer clear of dealerships (and I understand that), it might be worth considering to see what they come up with.

Yes, it's reluctantly booked into the dealership this week, although I intended to take it to a turbo diesel specialist to investigate. They've previous had the car for excessive periods of time to fix seemingly trivial problems (glow plug bus bar).

[stallingI30]

Apologies for the barrage of posts! My son isn't familiar with the turbo diesel engine but has thrown around the idea that it may be a boost or vacuum leak. Are there any boost/vacuum lines that I should check, or connections in the inlet system that are known to cause issues like this?

[Dazzler]

I had the same problem with Cyril,just before the stalling the revs would be limited to 3000 rpm,but after accelerating to that and then backing off He would stall,I would have to try one two or three times before he would start again,I am pretty sure from memory it was a faulty air fuel mixture sensor,once replaced it has never been an issue to date again

I had a look at the air fuel sensor (the one immediately prior to the inlet manifold, I'm not sure if this is a mass airflow sensor). The sensor had a thick layer of black oily gooey deposits which I cleaned off. This didn't have any effect either... the problem remains.

Just cleaning the outside of it wouldn't necessarily fix the problem. What Rick has said is similar to what i was suggesting. I strongly recommend to get the dealer to look at this as a possible warranty fix.