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700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars |
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High idle 940Views : 3434 Replies : 11Users Viewing This Thread : |
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Jan 11th, 2018, 12:22 | #1 |
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Last Online: Mar 29th, 2018 07:27
Join Date: Jul 2017
Location: Skaabu
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High idle 940
Tomgang has managed to go high on my -98 lt, approx. 12-1500 rpm.
Has followed a bit of extra with the last time and it's after the engine has gotten hot and I've driven a few miles, and then it seems like it goes down to normal rpm when the car is standing still/wheels not turn. Otherwise it starts okay and normal, no cheating electricity The damper housing, lmm, idle engine is cleaned and tps "clicks". Changed. Idling valve Air mass sesnor Temp sensor for ecu Throttle pos. switch Vacum hoses on intake manifold Fuel ecu Crank sensor Abs/speed sensor on rear axel When I shut og the engine and start it up again the problem is not there until the car has been shut of for aprox. 6-7 hours, depend of the outside temp. The problem seems to increase when outsidw temp is low from aprox. +5 C and lower. The problem comes after driving to the engine temp gauge shows about 1/4 warmed up. In the winter time when I use the electric engine heater (230 V ac) and the engine i a little bit warmed up the idle is normal. It is a very old thread on this forum were the car is acting exactly like mine. Hope there is someone who can help with this irritating issue. |
Jan 12th, 2018, 11:37 | #2 |
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Last Online: Apr 4th, 2024 17:58
Join Date: Oct 2015
Location: watford
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Not much help but I have a high idle problem too, It only occurs after I have driven the car fast or on WOT, If I switch it off and start again it immediately goes away. Idle is same as yours at around 1500rpm when fast. It doesn't bother me too much but I wouldn't mind knowing how to sort it out, or is it just ' one of those glitches?'
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Jan 12th, 2018, 12:39 | #3 |
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Last Online: Today 08:57
Join Date: Feb 2006
Location: Amersfoort (NL)
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High idle
The engine management can only adjust the idle speed when the engine is warm and speed is (almost) zero. If you start a cold engine, the idle speed setting will be set higher because of additional friction of cold engine. During driving the engine warms up, but if you do not stop, the engine management system has no opportunity to re-adjust the idle speed for warm engine. The idle speed will then be higher, especially when the outside temperature is low. You need to fully stop and wait for two or three seconds before the idle speed is lowered back to 800 rpm. Can be annoying if you get into stop-and-go traffic without a chance to stand still long enough.
Sometimes it happens that I stop after having driven continuously from cold start for some time, the idle speed will be lowered but stick somewhere around 1000 rpm. If I then slightly let go of the clutch to let the engine speed drop to 6 or 700 rpm for a moment. Then the engine managament sets the speed at a steady 800 rpm. |
Jan 12th, 2018, 12:45 | #4 |
SilverBrick Lives!
Last Online: Apr 27th, 2024 22:18
Join Date: Apr 2015
Location: Poynton, Cheshire
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In my 940, the idle air valve was only operated when the revs drop low enough to need it, so unless it is sticking, it should be closed during normal driving.
If it is slow to react then it needs cleaning (and lubricating using clean engine oil - safe on CAT etc), but as the OP says they have replaced it (not cheap I guess!) then that shouldn't be an issue. Is there an air-leak causing more air to go into the engine, so it behaves as if the idle valve is open?
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Jan 13th, 2018, 10:49 | #5 |
Junior Member
Last Online: Mar 29th, 2018 07:27
Join Date: Jul 2017
Location: Skaabu
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Thank you for all answers.
It makes sence that the engine managemanet can only adjust idle speed when it is warm, on a other side I just can`t understand it, because the engine did not behave in this way for until 3-4 years ago. I also had a 1996 940 with B230FK before this car who did not behave like this. All the parts I have replaced is original parts. Last edited by 98945lt; Jan 13th, 2018 at 11:17. |
Jan 14th, 2018, 11:14 | #6 |
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Last Online: Oct 31st, 2022 17:05
Join Date: Sep 2010
Location: Caterham
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High 98945lt,
There is an old thread on here that might help (see below). Check out my response which is the last reply on the thread as to how I got a cheap fix to my high tick over. https://www.volvoforums.org.uk/showthread.php?t=248168 Hope this helps. Cheers, LeeP |
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