99 V40 unidentified sensor & stalls when cold

Shane001 · Post by **Shane001** » 22 Jul 2013, 05:48

Hi guys,

New to Volvo's and new to the forum

Just bought the wife a 99 V40 2.0T SE, looks to be in mostly good condition, few little things to fix up, but one strange problem is when cold it starts fine but then stalls after a couple of seconds. Holding the revs around 2000rpm for a few minutes until it's warm and it seems to be OK then, but while warming up every say 5 to 10 seconds it hesitates and wants to stall. Keeping the revs up keeps it running.

Now I'm not sure whether this is related or not but I noticed this sensor hidden away under the fuse box. I can't see anything that it would connect into, but obviously it does as it has an o-ring seal.

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It looks like this must be where it mounts on the firewall;

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I've been searching Google for engine bay layouts to try and identify this for nearly an hour with no luck. Can anyone shed some light on what this is please? Also any ideas on the cold engine stalling issue?

Thanks very much for reading

Shane001 · Post by **Shane001** » 22 Jul 2013, 08:04

Well after researching this all night, I still haven't clearly identified the sensor, it's either a MAP sensor or a Barometric sensor (why does it have a barometric sensor?).

But it looks like my stalling problem may be either the fpr or the IAV. will check them both tomorrow.

Post by **jimmy57** » 22 Jul 2013, 09:23

That is a barometric sensor. No reason for the o ring but I have seen many stuck out if the breeze with an o ring on them...

If you start it and give it a litle throttle does it run OK then?
Trying to determine if it is low idle air flow or lean mixture.

The throttle could be very dirty and the air that normally passes by supplementing what comes through idle air vavle is not enough.

Shane001 · Post by **Shane001** » 23 Jul 2013, 04:47

Managed to find the problem. Was a broken vacuum hose on the manifold, once fixed starts and idles perfectly, seems to run a bit better today also. Nice to have an easy one

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Something else I noticed today though that's a bit worrying, the fuel return line is disconnected and capped off. No idea why this would have been done? Runs fine as is and no sign of any leaking fuel. No smell of fuel leaking back through the vac hose from the fpr either.

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