HIGH REVS AT IDLE

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alan325i
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Tue May 09, 2006 1:21 pm

Hi

When i slow down the revs go down........ as soon as i come to a stand still and depress the clutch pedal the revs shoot up to 1.5k.

When warm it will rev @ 900-1k which is a bit high

Even when driving and you back off the pedal you still feel the car pulling

Is this the rev control valve?
PaulyV
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Tue May 09, 2006 4:35 pm

The most basic possible reason I know, however check the sleeve of the throttle cable is firmly into the socket where it belongs. if it has been pulled out slightly it rarely returns to where it should resulting in revs at just the level you mention.

best

Pauly
1990 318i LUX, Alpine White, 80,000 miles, as close to mint as I'll ever get.
stonesie
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Tue May 09, 2006 8:59 pm

TPS.... thats what it turned out to be when mine did this, fuel consumption also increased.

When you check the throttle cable moove the throttle just a little, you should hear a faint click...
fannyj
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Tue May 09, 2006 10:10 pm

how your thermostat ?
i had a similar problem,the car would feel fine when driving but as soon as i came to standstill the revs would rest at 1100rpm, then eventually drop to 800rpm. Replace the thermostat and it's all good now.
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Mops
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Wed May 10, 2006 4:30 am

sounds like tps ot broken.

unplug and check whether it makes any difference to idle.
1985/E30/325i coupe/5 speed/125k miles/shortshift/megasquirt II ECU controlling fuel and spark with custom ignitor and ICV mods/LC-1 wbo2/collecting parts for FI
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alan325i
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Wed May 10, 2006 6:49 am

whats the tps ot???
Mops
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Wed May 10, 2006 9:27 am

tps is throttle position sensor (or switch in case of stock m20). it's under the throttle plate. it tells the ecu when your foot is off the throttle. check electrical connections to it.
1985/E30/325i coupe/5 speed/125k miles/shortshift/megasquirt II ECU controlling fuel and spark with custom ignitor and ICV mods/LC-1 wbo2/collecting parts for FI
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Brianmoooore
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Wed May 10, 2006 9:32 am

alan325i wrote:whats the tps ot???
Switch mounted directly underneath the throttle body, on the bottom end of the shaft that carries the throttle butterfly.
Take the big air hose from the air filter to the throttle body off (Check it for splits), pull the TPS plug and get a meter on the switch contacts.
Pins 1 and 2 should be short circuit (zero ohms) with the throttle closed, going open circuit just as the throttle is moved off its stop.
Pins 1 and 3 should be open circuit at idle,, and go short circuit at about 2/3 throttle.
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alan325i
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Wed May 10, 2006 10:20 am

Thanx for the help, i have a few spares Throttle bodies and switches so will just replace the whole lot and see how that goes
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alan325i
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Fri May 12, 2006 11:14 am

Spot on again Brian, changed the throttle body and idling sweet now. :D

Where do u get your knowlegde of BM's do u work for them?
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