Cut out at low idle

[highpass]

Hello!

Recently my '93 240 auto has started to play silly buggers (...again)

At idle it is a gnat's whisker away from cutting out. At 5mph plus there is no issue, but at anything below that driving is now a game of ensuring i don't let off the accelerator too quickly and/or shifting into 2 when at low speed to keep the revs high.

Here are some things I've read about that seem to be likely:

MAF (disconnecting this has no effect - I have replaced the part nonetheless)
IAC valve
Fuel pump relay (this was replaced a year ago)
Incorrectly gapped spark plugs (these were changed some months ago)

...is there anything else I need to look at?

Cheers!
HP

[Bugjam1999]

My car had a really low idle that cut out, the same as you're describing - turned out to be the idle air control valve sticking/not opening properly.

To cure it used this guide:

https://www.volvoclub.org.uk/faq/EngineOBDCodes.html

this link will also help:

http://www.volvoforums.org.uk/showthread.php?t=122391

and used 'diagnostic mode three' which cycles various components to check their operation, including the idle air control valve. So with the rubber hoses disconnected, but the electrical connector still connected, I sprayed WD40 into every opening of the IAC as it was cycling backwards and forwards - fixed

The other common cause of idling problems I've heard of online (although not had myself) is one of the vacuum lines leaking slightly - I bought a couple of metres of silicone tubing from ebay and replaced the lot as a precaution, which cost less than £5 I think.

hope that helps...

[Stephen Edwin]

Have you read the fault codes? There is a guide to this in 200 Series Rticles.

Were there any fault code to indicate replacing the MAF? If not please keep the old MAF safely in case of future need.

[Stephen Edwin]

Accidental duplicate.


.

[Clifford Pope]

The Idle Air valve is easy to fix or eliminate. Just remove it, squirt in some WD40, and waggle the rotating valve about with something blunt.

Watch out that someone in the past hasn't fiddled with the throttle stop screw in an attempt to fix this.

[highpass]

Thanks for the suggestions everyone. Here is an update:

• I can't check OBD codes because the OBD doesn't work (may simply be a dead LED)

• Swapped out the MAF (and kept the old one), no difference

• Swapped out the fuel pump relay - no improvement at start but seems to be better lurching in traffic - this review is based on a pre-8AM/coffee drive to work so may be inaccurate

• I have a new IAC arriving today which I'll swap out over the weekend

Clifford - how would I know if someone has tried fiddling with the screw?

Cheers!

[Clifford Pope]

If when you have cleaned the IAV it then idles too fast, that is often because someone in the past has attempted to correct the slow running by turning up the screw.
Base setting is just a matter of inserting a rod of the right diameter into the throttle body to limit the closure of the butterfly, and then adjusting the screw until it just touches the stop. Haynes etc will tell you size of a handy drill bit to use.