C30 Engine : Intermittent stalling

[superhifi]

Hi all, having an intermittent issue with my Petrol 2.0 C30 the last couple of weeks, hoping someone can give me some pointers...

I first noticed it when coming up to a roundabout, as I dip the clutch just before coming to a stop the engine just died. It took a bit of effort to get it started again, engine turning over but not starting, and after a few seconds it started and everything was fine for the rest of my journey.

A few days later I was on a windy county road, doing a steady 40MPH and noticed the car had become a bit jumpy, and not running nice. I could put my foot down on the accelerator and it would seem hesitant to accelerate, but would eventually go. Then i noticed if I took the car out of gear, feet off all the peddles, and let the revs drop down to idle, it would stall. Again after a bit of effort it would start again.

This has happened 5 times in the last 2 weeks, and the rest of the time it's driving nice and as I would expect. Any pointers as to where I should start looking under the bonnet?

TIA

Edit: I should add, that at no point do I get any error lights on the dash...

[volvopilot]

throttle body position sensor that has gone bad? Maybe a bad/dirty throttle body. I had similar problems with my 1.8L petrol which is almost the same engine. It was not stalling but almost.

I removed the airbox (torx) and cleaned the throttle body with some carb cleaner and a towel. Might be worth a look.

[superhifi]

Thanks, did you remove the throttle body, or clean it in situ? I'm guessing it's easier to clean off the car?

I've kind of assumed that if it was a sensor/electrical issue that the car would detect it and flag up a warning light on the dash. Unless whatever is going on is not 'serious' enough to put a light on?

[FracturedButWhole]

Hi,

Just to add, I found it easier to remove it completely. Disconnect battery and then its's airbox hose clamp to unlock, sensor connection and 4 bolts. Then you can actually unscrew sensor from housing - I did that to avoid any potential contamination with carb cleaner, just in case I went a little bit enthusiastic with spraying. My throttle was really dirty, it took multiple applications of carb cleaner and wiping of dissolved crud. Eventually it all came all nice and shiny. 30 mins. all in. Installation is reverse of removal.

Good luck.

[superhifi]

Cheers for the pointers, i'll give this a go this evening when I get home from work.

Driving to France on Saturday for a week, so ideally i'd like to nip this in the bud before then!

Will keep you updated. J

[superhifi]

Right, so had the throttle body off earlier, given it a good clean with some carb cleaner, and put it all back together. Went for a quick test drive with no issues, but shall see how I get on tomorrow morning on the way to work.

Incidentally, when I had the throttle body off the car, I noticed that in its natural position it isn’t quite closed, and can be pushed fully closed, but then it springs open again. Is this by design? I have a photo, but can’t upload from my phone, I’ll get it uploaded tomorrow morning.

[FracturedButWhole]

Hi there,
Yes, it is by design. It has to let a little bit of air, even in the "closed" position.

Cheers

[volvo for ever]

Originally Posted by superhifi

Hi all, having an intermittent issue with my Petrol 2.0 C30 the last couple of weeks, hoping someone can give me some pointers...

I first noticed it when coming up to a roundabout, as I dip the clutch just before coming to a stop the engine just died. It took a bit of effort to get it started again, engine turning over but not starting, and after a few seconds it started and everything was fine for the rest of my journey.

A few days later I was on a windy county road, doing a steady 40MPH and noticed the car had become a bit jumpy, and not running nice. I could put my foot down on the accelerator and it would seem hesitant to accelerate, but would eventually go. Then i noticed if I took the car out of gear, feet off all the peddles, and let the revs drop down to idle, it would stall. Again after a bit of effort it would start again.

Y

This has happened 5 times in the last 2 weeks, and the rest of the time it's driving nice and as I would expect. Any pointers as to where I should start looking under the bonnet?

TIA

Edit: I should add, that at no point do I get any error lights on the dash...

You must check the cem for water ingress

[volvo for ever]

There was also mod on throttle unit you had to renew wiring sometimes throttle unit itself make sure sw is on latest and also reset adaption for all

Important takes minutes to check the cem unit water ingress can cause variety of problems cutting out is just one of them

[superhifi]

Originally Posted by volvo for ever

You must check the cem for water ingress

CEM or ECU? My understanding the CEM is inside the car? I'm going to try and have a look this week at the ECU (ie the other end of the cabling fom the TPS.

Interestingly it's been dry for a good week now, and the car has been behaving itself... right up until yesterday afternoon... (warm, dry and sunny)...