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700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars |
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Idle high when rainy. Drops to 1000 when car comes to a stopViews : 1309 Replies : 33Users Viewing This Thread : |
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Jan 5th, 2024, 16:36 | #11 |
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V70 D5 SE Geartronic 215bhp Saville Grey 2012MY 940 LPT Manual 1996 740 SE 1990 |
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Jan 5th, 2024, 17:11 | #12 |
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What does it mean "to the stop but no further"?
Am I supposed to turn it all to the A side, then turn gently until the click is heard (which I did hear) and then keep turning until the end? I don't understand what "stop" means, or "no further". If it's the end, you couldn't really turn it no further, right? Also I don't understand what it means to hold the "throttle disc". Does that mean I have to disconnect the inlet hose and hold the disc/butterfly closed and turn the sensor all the way after the click, while guaranteeing the disc remains closed? Did you get the chance to see my comment with the codes i read from the car? Any opinion?
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Jan 6th, 2024, 10:54 | #13 |
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I just turn it gently one way and then back the other way until it clicks, then tighten the bolts and open the throttle and listen for the click again. Sometimes tightening the bolts can alter the position just slightly and stop it clicking - might need a couple of goes at it.
I don't think this is your cause of high idle though, unless it is not clicking now?
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MY97 940 CD LPT Super Sports Edition 2 Turbo, Midnight Purple, 175,000 miles. Last edited by baggy798; Jan 6th, 2024 at 10:56. |
Jan 6th, 2024, 14:26 | #14 | |
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But i was explaining specifically that my idle stays at 1500 when it's rainy/wet. And it stays that high until the car stops moving. I think it eventually normalizes after a while. but I still have the pesky vibration and inconsistent idle that i haven't solved yet.
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Jan 8th, 2024, 12:04 | #15 |
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Ok. My idle is 850-900 and rock steady but the idle valve is bypassed so not really comparable. Never seen the 1500 (sometimes stays at 2000) rpm idle issue ever definitely solved, otherwise I wouldn't have bypassed it!
Do you mean a slight fluctuating idle when you say vibration? How crusty are your intake manifold and throttle body gaskets? I think you've changed all the vac hoses already? Do clean the idle valve and/or test a second hand one.
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MY97 940 CD LPT Super Sports Edition 2 Turbo, Midnight Purple, 175,000 miles. |
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Jan 8th, 2024, 12:45 | #16 |
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Tps
The only function of the TPS is to tell the ECU when the throttle is closed. Together with the current vehicle speed the ECU decides when to stop injecting (during coasting) or when to re-adjust the idle speed. For obvious reasons the ECU should not re-adjust the idle engine speed if a higher speed is caused by pressing the throttle pedal (TPS open) and/or if caused by the vehicle speed driving the engine (vehicle speed > 0).
A correctly set TPS will open just when the throttle cable starts to open the throttle plate. If this is set too critical, the ECU will not adjust the idle speed and maintain the initial idle speed setting of when the (cold) engine was started. Note it will also not re-adjust when the vehicle has been constantly moving since its first startup. Re-adjusting takes one or two seconds of standstill with a warmed up engine. The idle speed may be higher than normal, but it should not be vibrating or being irregular (or is the AC switching on/off?). Is this only in wet / damp conditions? That would be pointing more towards bad HT leads / distributor cap. |
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Jan 9th, 2024, 23:45 | #17 | |
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How did you bypass the IAC? I have cleaned it, but it is one of the suspected culprits. Other being MAF. Intake hoses are in great shape. Turbo inlet too. Vacuum too. i haven't switched some of the hoses that go inside the car. I suspect that one goes to the instrument cluster, the other is AC related!? And the cruise control!? It's the ones that are plastic. But they look fine. Also vacuum tests didn't show leaks. Intake gasket looks great. It only has 50k km or so. I'm at a loss with this crap. EDIT: Here is the link to the video of the "misfire"/fluctuation and vibration/shake: [YOUTUBE]https://youtu.be/bTt45bXXayA?si=OwaxsYwq6VZ2rviQ[/YOUTUBE]
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Proud owner of a 1997 940 2.3 lpt Manual with 501,000km. Last edited by SalvadorP; Jan 10th, 2024 at 00:04. |
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Jan 10th, 2024, 00:01 | #18 | |
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It has nothing to do with the AC. Also Ht leads are new, plugs well gapped, etc. IAC cleaned but not tested. MAF tested and it gave abnormal readings. At the time I asked you your opinion about the values, because you were helping me figure it out, but you must have missed my reply. This wet thing does sound a lot like rotor/cap cause I've had similar issues on an Opel Corsa years ago. But the cap and the rotor do look in great condition and I cleaned them and it made no difference. Here is video of the needle at idle, like it is normally, when the air is dry/normal. Do you think it's is a misfire? [YOUTUBE]https://www.youtube.com/watch?v=bTt45bXXayA[/YOUTUBE] If you see the video, you can see and hear the car shake when the needle drops.
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Jan 10th, 2024, 13:41 | #19 |
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Alternator
It seems very rythmic, as you say. It could be the IAC fluctuating, but also a variable load on the engine. Have you tried running it with the alternator belt removed?
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Jan 10th, 2024, 14:44 | #20 | |
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No, I have not. It never occured to me to do that. Your reasoning is that a faulty alternator could make the load on the engine be uneven and therefore make the idle drop when it's under increased load? Do you think this could be at all MAF related? When I tested MAF these were the values: "I've tested voltage between #2 and #3. 1.42 with ignition on. At idle, 2.4, under acceleration 3.09."
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