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200 Series General Forum for the Volvo 240 and 260 cars |
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230F idle speedViews : 756 Replies : 12Users Viewing This Thread : |
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Dec 31st, 2018, 12:29 | #1 |
newish member
Last Online: Nov 7th, 2020 23:35
Join Date: Jan 2016
Location: London
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230F idle speed
...almost Happy New Year fellow 240ers! Two conundrums I face which I am having a problem resolving:
My 240 (2.3 Bosch LH2.4) generally idles around 1000 RPM up to 1500 RPM. Occasionally I can get it to idle at about 750 where it should be and I do this by flicking the ignition off and back on again. In very cold weather it seems more able to idle at the right speed and in warm weather less able to. Something is clearly not working correctly There are no fault codes on the reader, the economy is reasonable (but clearly not going to be where it should be). It passed it's MOT last year by a country mile and it drives fine It's had a new exhaust, Oxygen sensor, Idle Control Valve and the throttle has been correctly set up a few months ago So why won't it idle at the right speed? I am wondering whether cleaning up the ECU electrical contacts might help, whether a new temperature sender might help and/or whether the MAF is at fault? Anyone shed any light on this matter? I have also posted another (possibly related) conundrum... Thanks all! Nick |
Dec 31st, 2018, 17:21 | #2 |
Not an expert but ...
Last Online: Apr 26th, 2024 12:45
Join Date: Dec 2001
Location: Boncath
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I've always noticed that the Idle Air Valve is very sensitive to accumulated deposits - that fine black slightly oily sooty stuff that gradually accumulates in the throttle body and on the butterfly flap.
Have you tried taking off the convoluted air duct, holding the throttle open with the wheel, and wiping as far as you can reach inside the TB with a rag wound round a stick, soaked in carb cleaner? Then remove the IAV and squirt in some cleaner. Clean the sliding valve with a soft brush, using a stick through the exit port to rotate the actuator. Check that it snaps closed. In fact it should close just a fraction open. I've found this sooting up happens quite quickly - I make it a sevice item about once every alternate oil change. A symptom that it needs doing is if the idle sticks too high as you describe, and can be corrected with a blip on the throttle. |
Jan 1st, 2019, 01:25 | #3 |
Ye olde Volvii galore!
Last Online: Dec 18th, 2023 11:23
Join Date: Oct 2017
Location: Sherborne
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Have you checked all of your vacuum hoses and intake bellows for leaks/cracks? If you have air ingress anywhere past the MAF these engines can display weird symptoms and get a little squirrelly to diagnose. I went through all this with my 744, found a split in the intake bellows which solved the majority of the idle issues I had. The throttle had been poorly set up by someone prior to my ownership too, so the TPS never engaged/disengaged...adjusting that up correctly remedied the rest of the issues.
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Jan 7th, 2019, 00:09 | #4 |
newish member
Last Online: Nov 7th, 2020 23:35
Join Date: Jan 2016
Location: London
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Thanks both
Oops la! MOT due 04/01 and got overlooked. t'will be done on the 11th and at the same time, we will have another go with the idle speed and flat spot My money is now an air leak issue. So before the 11th, I am going to have a visual check of all hoses and tweak-up all the jubilee clips The only electrical parts of the fuel system I have not replaced are temperature sender, MAF, cold start valve, all of which could be contributors but I think not at this point - my ignition flick trick no longer works, hence my hunch is that this is air leak rather than electrical... |
Jan 7th, 2019, 01:17 | #5 |
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Last Online: Oct 9th, 2022 04:41
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Location: Currumbin, Queensland
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While you're on the hunt for vacuum leaks, make sure there isn't fuel in the vacuum hose going between the intake manifold and the fuel pressure regulator (FPR). The FPR has a diaphragm in it, which when leaking will lead to fuel entering the intake manifold. This can cause a high idle, increased fuel consumption and driveability issues related to having a rich mixture. The FPR is very easily replaced, and I believe costs less than 100 Euros.
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Jan 7th, 2019, 12:05 | #6 |
Not an expert but ...
Last Online: Apr 26th, 2024 12:45
Join Date: Dec 2001
Location: Boncath
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I think you can crudely test the pressure regulator by disconnecting the pipe from the injector rail and sniffing it. Petrol smell = petrol leaking through the diaphram.
If you suck on the pipe you can feel the diapham operating. Put your tongue over it and see if it holds the vacuum. |
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