Having a few prob's here, not sure if they're all connected or not. I've never worked on my S40 to any great extent, so not too familiar with it.

Firstly, when the engine idles, the rev's are not steady, they drop from around 750rpm to 400ish rpm then returns back to 750, drops, rises, drops, rises, you get the idea. It's not the tach, you can hear the engine speed increace / decreace too.

If you lightly blip the gas pedel / accelerator rev's pick up fine, then drop to around 200rpm (almost cuts out) then begins fluctuating again.

Last night when I started the car it sonded like someone had swapped it for a diesel and the engine management light was on. When I set off there was a distinct lack of power, felt as though I was towing a 2 tonne trailer, the more I put my foot down the less power I seemed to have.
The car has always made an electrical sounding whine when idling, but last night this whine was realy tinny sounding.

When I got to sister in laws I checked all of the vacuum hoses with engine running, couldn't find anything that affected the fluctuating idle.

For the whole of the two hour trip home it was fine.

I'm stumped and don't even know where to start, I hate hate hate modern engines.

Stu.

:o Maybe a fault in the ecu, confusing the unit as to what's happening. I got the harness replaced as it kept tripping the immobiliser. If anyone nearby has a fault reader plug it in just to see what comes up. It may be major. This is the problem with modern cars, too much electonics!

Had a similar problem with my V40 re idle revs dropping/surging/dropping/surging & so on, accompanied by the DSA warning light illuminating. Blipping the throttle cured it (and the DSA light), but as it was under warranty I put it into the Volvo dealer anyway.

Problem was dealt with by the dealer under warranty - on my suggestion they cleaned the throttle body & idle motor. They also downloaded latest software onto the ECU, which I thought it should already have had because it came with a full Volvo main dealer service history!

Hope this helps.

BB
:beer:

Engine management light has gone out on it's own accord. Still fluctuating idle though. Still have full power too.

I'll have a go at cleaning throttle body and idle motor in a.m.

Quick question, whats the best method of cleaning also where is the idle motor and what does it look like?

Thanks a million.

I'll let you know how I get on.

Stu.

An aerosol can of carb cleaner should do the trick, get one with a long plastic nozzle so you can get into all the nooks & crannies.

Remove the plastic engine cover & follow the air inlet duct towards the inlet manifold. This duct should be attached to the throttle body, which in turn is connected to the inlet manifold. If you remove it from the manifold, it is best to use a new gasket when re-assembling. Ensure no air leaks will occur after re-assembly.

Repeat cleaning every 20,000 miles!

Ensure that the air filter is changed regularly/not clogged. As well as poor mpg etc., a clogged air filter can cause tickover problems.

BB
:57:

Gave throttle body a good cleaning, just behind the butterfly jobby was caked with black gunge.

All sparkling now though, idles and runs fine.

Cheers.

Stu.

:banana: Result!

Glad to hear all OK now.

Have you looked at the UK section under the Regional/Europe forum? Mong Man is trying to get UK members together, maybe in March.

Regards.

BB
:thumbsup:

cheers for the plug bbt4. only you interested so far. come on people.

Why not, count me in!

Is it just the S40 owners you're angling after?

Stu.

:460: Great! Certainly not restricted just to the 40 series - anything that can legitimately wear a Volvo badge is more than welcome to bring its owner & significant others/friends along too!!!

Maybe that's how we should spread the word Mong Man/I have a nut leftover - not just via the UK section!

BB
:grouphug: