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700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars |
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740 brakes affecting idle?Views : 1928 Replies : 15Users Viewing This Thread : |
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Jun 22nd, 2010, 23:15 | #1 |
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740 brakes affecting idle?
hello all,
I've noticed that when my car is cold it will idle up and down at 500 rpm and 'chug' once warmed up it will run perfect...however i've noticed if i pump the brake pedal quickly on idle that same chugging returns and i assume when brake vacuum rebuilds again, the idle smooths out once again.....should there be a non return valve on the vacuum pipe between the manifold and the master cylinder? |
Jun 22nd, 2010, 23:25 | #2 | |
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Jun 22nd, 2010, 23:37 | #3 | |
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there is a cold start problem with the car,dependant on engine variant.
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Jun 23rd, 2010, 07:25 | #4 |
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Thank you guys, i checked and the vacuum is still there after the engine is turned off, even when left sitting over night so we know its not the check valve in this case...
the engine is the 'B200E' (2.0 , continuous injection, with no catalytic converter, it runs on lead replacement petrol, but would be nice if i could get hold of real leaded fuel. I've noticed theres no 'engine light' does that mean theres no onboard diagnostics or fuel injection computer, or is this a purely mechanical system? Sorry for so many questions, this is my first volvo :-) |
Jun 23rd, 2010, 08:45 | #5 |
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Fairly normal for slightly rough idle when cold on these engines, any hot start issues?
No electronics for the injection on these engines, other than the cold start injector.
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Jun 23rd, 2010, 09:15 | #6 |
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hi fella - my B200e runs very happily on unleaded with no problems - Volvos were designed for Unleaded very early on so highly likely you can use premium unleaded - though of course they do prefer to run on the higher octane stuff and mine runs a lot happier on v-power - no issues other than that. Might save you a pretty penny and be easier to get hold of....
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Jun 27th, 2010, 22:13 | #7 | |
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No hot start issues whatsoever....its a bit of a strange one..... i'm now suspecting the idle air control valve...(auxillary air valve) |
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Jun 27th, 2010, 23:39 | #8 | |
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I am assuming it is a 1988 740 from your user name.
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Jun 30th, 2010, 14:18 | #9 |
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Jun 30th, 2010, 18:30 | #10 | |
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pumping the brake pedal will obviously affect tickover as each pump lets air into the inlet manifold which will affect the mixture,by the sound of things yours is running rich on tickover if the chugging is better when you pump the pedal
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