240 - Fast idle after cold start

leftfootleashed · Apr 19th, 2012, 10:30

Something that's been niggling me a little since I bought my 240 fairly recently: after starting from cold it idles very briefly at the speed I expect (~1200rpm) then jumps quickly to about 2000, before gradually coming back down to 1200 over the course of 30 seconds or so. If started from fairly warm, this doesn't happen - it's like the car is warming itself up. Is this normal for a 240, a Volvo, or just any car of this age?

I'm not really worried about this, more curious, but should I be?

Clifford Pope · Apr 19th, 2012, 13:38

Which fuel system does it have?

If it's the LH injection then the most likely cause is dirt in the Idle Air Valve - an alloy canister mounted under the inlet manifold, with two thick pipes connected to it. Remove it, spray carb cleaner or WD40 into the valve bit, and wipe the inside with a thin soft paintbrush. Use the wooden end to rotate the valve and squirt in some more fluid.
The sliding segment should park with a small gap, and snap back when rotated and released.

It's also worth removing the air intake and similarly cleaning the throttle body and butterfly.

leftfootleashed · Apr 21st, 2012, 16:19

I think it's the LH injection, though to be honest I'm not sure.

Is this what you mean? Not really under the inlet manifold, but it's the only thing I can see that vaguely fits your description.

morsing · Apr 21st, 2012, 20:59

Hi,

That's K-Jet.

leftfootleashed · Apr 21st, 2012, 23:29

I bow to your superior knowledge. I was a bit confused by the different injection systems, but I think I understand now - there's basically the K-Jet (mechanically distributed) and LH-Jet (electronic) yes? I was thrown by my Haynes manual referring to the K-Jet as CIS (continuous injection system) but they're the same right?

Anyway, I read up on the K-Jet system over at the aptly-named k-jet.org and from what I can see, the part in the picture above, the auxiliary air valve, performs roughly the same job as the idle air valve Clifford mentions, so I should take a look at that. Anything else that might cause this? Possibly a fault with the thermal time switch, causing the cold start injector to spray too long?

mrmeringo · Apr 21st, 2012, 23:32

I'm pretty sure thats a sealed unit

leftfootleashed · Apr 21st, 2012, 23:33

Quote:

Originally Posted by mrmeringo

I'm pretty sure thats a sealed unit

The auxiliary air valve or the thermal time switch?

mrmeringo · Apr 21st, 2012, 23:35

Quote:

Originally Posted by leftfootleashed

The auxiliary air valve or the thermal time switch?

Sorry, the one in your pic

leftfootleashed · Apr 21st, 2012, 23:42

The Haynes manual says it can be tested. You take it off and shine a torch down in to check it's open when it's cold, then hook it up to 12V - the heater element heats it up and after 5 minutes it should be shut. Simple enough. If it's faulty, I guess it's a replacement though, yes.

mrmeringo · Apr 21st, 2012, 23:46

Quote:

Originally Posted by leftfootleashed

The Haynes manual says it can be tested. You take it off and shine a torch down in to check it's open when it's cold, then hook it up to 12V - the heater element heats it up and after 5 minutes it should be shut. Simple enough. If it's faulty, I guess it's a replacement though, yes.

Haha, i only know cos i took mine off for the same reason and snapped the top off trying to be a smart a**e, so had to get another one

Apr 19th, 2012, 10:30	#1
leftfootleashed Perma-scarred Knuckles Last Online: Jan 30th, 2024 21:02 Join Date: Mar 2012 Location: Newcastle-upon-Tyne	240 - Fast idle after cold start Something that's been niggling me a little since I bought my 240 fairly recently: after starting from cold it idles very briefly at the speed I expect (~1200rpm) then jumps quickly to about 2000, before gradually coming back down to 1200 over the course of 30 seconds or so. If started from fairly warm, this doesn't happen - it's like the car is warming itself up. Is this normal for a 240, a Volvo, or just any car of this age? I'm not really worried about this, more curious, but should I be?

Apr 21st, 2012, 20:59	#4
morsing Premier Member Last Online: Today 10:26 Join Date: Dec 2001 Location: Aylesbury View Photos By: morsing	Hi, That's K-Jet. __________________ --- '89 Volvo 240GLT B230E/AW70 '14 Volvo V70 SE D4/M66 FWD '70 Chevrolet Chevelle Malibu '95 Saab 9000 CSE 2.0 Turbo Auto

Apr 19th, 2012, 13:38	#2
Clifford Pope Not an expert but ... Last Online: Today 08:33 Join Date: Dec 2001 Location: Boncath	Which fuel system does it have? If it's the LH injection then the most likely cause is dirt in the Idle Air Valve - an alloy canister mounted under the inlet manifold, with two thick pipes connected to it. Remove it, spray carb cleaner or WD40 into the valve bit, and wipe the inside with a thin soft paintbrush. Use the wooden end to rotate the valve and squirt in some more fluid. The sliding segment should park with a small gap, and snap back when rotated and released. It's also worth removing the air intake and similarly cleaning the throttle body and butterfly.

Apr 21st, 2012, 16:19	#3
leftfootleashed Perma-scarred Knuckles Last Online: Jan 30th, 2024 21:02 Join Date: Mar 2012 Location: Newcastle-upon-Tyne	I think it's the LH injection, though to be honest I'm not sure. Is this what you mean? Not really under the inlet manifold, but it's the only thing I can see that vaguely fits your description.

Apr 21st, 2012, 23:29	#5
leftfootleashed Perma-scarred Knuckles Last Online: Jan 30th, 2024 21:02 Join Date: Mar 2012 Location: Newcastle-upon-Tyne	I bow to your superior knowledge. I was a bit confused by the different injection systems, but I think I understand now - there's basically the K-Jet (mechanically distributed) and LH-Jet (electronic) yes? I was thrown by my Haynes manual referring to the K-Jet as CIS (continuous injection system) but they're the same right? Anyway, I read up on the K-Jet system over at the aptly-named k-jet.org and from what I can see, the part in the picture above, the auxiliary air valve, performs roughly the same job as the idle air valve Clifford mentions, so I should take a look at that. Anything else that might cause this? Possibly a fault with the thermal time switch, causing the cold start injector to spray too long?

Apr 21st, 2012, 23:32	#6
mrmeringo Tommy Meringo Last Online: Jun 28th, 2020 16:04 Join Date: Mar 2011 Location: Liverpool View Photos By: mrmeringo	I'm pretty sure thats a sealed unit

Apr 21st, 2012, 23:42	#9
leftfootleashed Perma-scarred Knuckles Last Online: Jan 30th, 2024 21:02 Join Date: Mar 2012 Location: Newcastle-upon-Tyne	The Haynes manual says it can be tested. You take it off and shine a torch down in to check it's open when it's cold, then hook it up to 12V - the heater element heats it up and after 5 minutes it should be shut. Simple enough. If it's faulty, I guess it's a replacement though, yes.

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