C30 Engine : Intermittent stalling

[superhifi]

Also, I should add, since cleaning the Throttle, I have been getting intermittent 'Reduced Engine Performance' warnings when turning the ignition on. This warning doesn't ever appear when driving though, only when first starting the car.

An ignition restart usually clears it and then the car starts fine. I wondered if this was something to do with the connector (which I had to unplug to remove the Throttle), so I unplugged it last night, gave it a clean with some contact cleaner and then plugged it back in, ensuring it was nice and snug. Hopefully that clears that issue up.

[FracturedButWhole]

Hi,

Out of curiosity - what exact error Vida throws? ECM-2008, otherwise known as P2008, by any chance?

Cheers

[superhifi]

It's giving me a 2135 - Faulty Throttle Signal.

Vida tells me: "The diagnostic trouble code is stored if the engine control module (ECM) registers that the correlation between the throttle unit potentiometer 1 and potentiometer 2 is incorrect or that one of them gives an incorrect signal."

I have some other codes showing realting to the throttle sensor, but I think these are left over from when I first started investigating this issue (and before I had Vida) when I unplugged it with the ignition on by mistake. I've tried to clear them but they don't seem to go. Looking at the details for them I can see they've only occurred once, but I can't clear them? Any pointers?

I'd really like to get all the codes clear so that when it next stalls on me I can connect in straight away and confirm my 'diagnosis' that it *is* the throttle sensor, and so I have some confidence that i'm spending my money on the right part to fix the problem!

[superhifi]

Right, a quick update for everyone, having not had much time to look at anything properly for a while...

Stalling issues were continuing once per journey, right up until Tuesday last week, when the problem just went away. Journeys to and from work were all fine, but by this point I had ordered a new Throttle Position Sensor (from here) and as the car still didn't always feel as smooth when accelerating as it should, I decided to fit it this morning.

Fairly simple to swap the TPS over, started up VIDA, cleared all my error codes, and everything looked good. Took it for a test drive, and within a couple of yards the 'Reduced Engine Performance' message was back. This was persistant, and very consistent. I got back home, removed the throttle body and positioned it so I could see it from inside the car, and then with the ignition on, but engine not running, I could see that as I gradually pressed the accelerator pedal the throttle was jumping all over the place, and then loosing position - ie with my foot off the accelerator pedal, the throttle would remain open. Vida was showing all sorts of errors about the sensor, Signal Too High, Signal Too Low, etc etc.

To try and troubleshoot this further, I took the new TPS off and refitted the old one, cleared the errors, and again leaving the throttle body in view, did my pedal test again. All smooth, no jumping, and no sticking.

So, i've now put my old Throttle Position Sensor back on the car, which is driving fine again, but still doesn't feel 100% between 1500RPM and 2500RPM. No error messages, no error codes.

Is it safe to assume the new TPS i bought is probably faulty?

[volvopilot]

it doesn't have to be faulty, did you re calibrate the throttle body after you installed the new sensor?

not sure how they do that, but I think it needs to be done when replacing the sensor.

[superhifi]

I did read that it is calibrated by turning the ignition on, but not starting the car, waiting 30 seconds, then ignition off and then on and start car.

I tried this a few times without it making any difference.

Does anyone know if this is the correct procedure?

[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)...

[LizardOfBodom]

Originally Posted by superhifi

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)...

Yep, he means CEM - the unit that is under glovebox, passenger footwell. Some symptoms can in fact indicate a CEM issue. It is prone to water damage (sunroof issue or even heater core blowout) and also to connector problems due to mechanical movement. Worth a check.