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S40 / V40 '96-'04 General Forum for the Volvo S40 and V40 (Classic) Series from 1995-2004. |
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Revs rising & falling at idle - never happened beforeViews : 954 Replies : 15Users Viewing This Thread : |
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Jun 12th, 2019, 16:45 | #1 |
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Revs rising & falling at idle - never happened before
Our 1.6 manual X reg has, sometimes, started to surge or drop it's revs when at low speed.
We've owned it for around 7 months and it's never happened before. Symptoms are: 1. revs rising & falling without pressure on the accelerator, and 2. revs dropping when pulling away in a low gear, as if I've slipped my foot off the accelerator or selected too high a gear when pulling away. Our previous S40 1.8 had a noisy VVT (so I know the sound to listen for) but I can't hear any noise from this one so I don't know if that's causing this issue. When this happened for my wife, and again today for me the electric fan stayed on for a few minutes once the car was parked up, but normally the fan never stays on when we've parked, even after a long motorway journey. I've checked the water level & that appears correct, so I don't believe it's overheating that's causing the fan to stay on. The only additional observation I can make is that the CEL is on, but that's been on for months & as it's a mid-phase car, when I plug a fault reader in there are no codes to be read. I appreciate that the two might be related, but as this issue's never occurred until the last 2-3 days it seems perhaps unlikely. Mileage is c. 145k. I've searched on here but can't find any suggestions, other than " ... carb cleaner for the throttle body and ICV ..." so I'd appreciate any suggestions as to what might be causing this. Thanks
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Jun 12th, 2019, 18:10 | #2 |
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The VVT will NOT create a surging idle,-the Idle Air Control Valve will, as will a vacuum leak. Remove the IACV and clean it with carb cleaner etc. Lubricate it with WD40. Is it functioning electrically? Does it get the 12 volts it's supposed to get?
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Jun 13th, 2019, 14:21 | #3 |
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thx emtor.
I managed to find quite a few more posts on here after putting mine up & they also mentioned the -the Idle Air Control Valve. Will check things out over the weekend, assuming it stops raining long enough for me to have a go!
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Now: 04 reg V70 2.4 SE 2.4 auto 177k Then: Volvo, Saab, BMW, MB, Ford, Vx, Opel, Fiat, Rover, Porsche, Alfa, Austin, Renault, etc |
Jun 14th, 2019, 12:50 | #4 |
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The IACV may have a leaking gasket, it may be stuck mechanically due to oil residue and dirt, or the solenoid may be open circuit or shorted, or it all works but does not get any voltage from the harness. If all checks out OK, then check for vacuum leaks somewhere/anywhere.
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Jun 14th, 2019, 18:27 | #5 |
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Thx.
Looks like the rain's finally stopped so I'll check under the bonnet this weekend.
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Now: 04 reg V70 2.4 SE 2.4 auto 177k Then: Volvo, Saab, BMW, MB, Ford, Vx, Opel, Fiat, Rover, Porsche, Alfa, Austin, Renault, etc |
Jun 14th, 2019, 18:54 | #6 | |
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A quick look on ebay showed the only gaskets were being sold out from the US for $20 + postage! https://www.ebay.co.uk/sch/i.html?_o...volvo&_sacat=0 I don't fancy leaving my wife car-less for the school run on Monday!
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Now: 04 reg V70 2.4 SE 2.4 auto 177k Then: Volvo, Saab, BMW, MB, Ford, Vx, Opel, Fiat, Rover, Porsche, Alfa, Austin, Renault, etc Last edited by CharlesStevenson; Jun 14th, 2019 at 18:57. |
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Jun 14th, 2019, 20:55 | #7 | |
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Quote:
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2003 V40 1.9T B4204T4, 197,000miles (sold but alive!), 2004 S60 2.5T, 160,000miles, 2010 V70 3.2, 125,000miles, 2002 V70XC 2.4, 175,000miles Click here for my x40 and V70 P3 repair guides |
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Jun 16th, 2019, 09:23 | #8 | |
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Quote:
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Jun 16th, 2019, 10:12 | #9 |
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That's a neat idea re the dishwasher soap and the packing.
I imagine you mean the Tetra Pak style aseptic packaging container material. It'd be good to be able to use some of those packs rather than simply throw them away.
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Now: 04 reg V70 2.4 SE 2.4 auto 177k Then: Volvo, Saab, BMW, MB, Ford, Vx, Opel, Fiat, Rover, Porsche, Alfa, Austin, Renault, etc |
Jun 16th, 2019, 12:30 | #10 | |
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Regarding dish washer soap: -I once changed piston rings on a one cylinder marine gas engine and could not for the life of me get the cylinder head to hold pressure. A couple of revs and the gasket blew. I tried all the gasket cements that existed in town but to no avail. In fact the cements only made it worse. An old man came by, halted and said: "Dish washer soap!" A thin coat on both sides and the engine ran happily and still does. Where there is not very high temps and pressures tetra pak and soap seems to work just fine. |
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