strange idle

[F7R-R5]

just wondering if anybody has got any ideas, on my 5 it sometimes idles high between 1.25k and 2k, it only does it if you drive the car hard, if u just drive around normally even going up the revs without full throttle its fine but as soon as u floor it, it idles high, i got told it something to do with the wire that goes to the speedo cable?

 

[Bigfoot]

if you are using the williams speedo cable then it will have a speed sensor on there, so when moving it keeps the revs at 1500. will only idle back down to 1000 of below after a second or two when stationary. if the cable is faulty it will possibly think you are still moving

 

[F7R-R5]

im running the gtt box as the 16v i had was no good, do you know which wire it is?

 

[16-valver]

it could be your iscv sticking mate if a 5 has one. it controls the amount of air in the inlet manifold for the tick over.

 

[F7R-R5]

na its not the iscv mate it only ticks over fast after u put your foot down hard, if you up up the revs with out hard reving its fine ticks over as normal

 

[The T.I.B.]

like bigfoot says the speedo cable could be responsible.

bearing in mind the f7p (and f7r?) speedo cable has an electronic road speed feed. without which the car will idle at 1500rpm

i damaged my speedo cable when i removed it earlier. if i just stick the end back into the gearbox its fine but when it comes out the idle doesnt settle

 

[Wicked Neo]

my speedo cable is not connected and to make up for the dodgy idle all i did was adjust the throttle stop screw (not the one under the rubber plug which you are not meant to tamper with but the one where the cable attaches to) to take the idle to 900rpm, no problems since

 

[Doc]

no stalling at the lights then simon?

 

[Wicked Neo]

nope, when i first put the engine back in after the clutch change, it did stall at the lights and i worked out it was because of the lack of speedo cable and no road speed sensor.
I could not use the speedo cable because the drive gear for the speedo cable on the gearbox is fubared.
So it was a matter of adjusting that stop screw once the engine was warmed up and had no problems since

 

[Neal R19]

but presumably its not quite as rosy when it's cold?

 

[Wicked Neo]

Actually its fine, it sits at 1000 rpm on cold and 850 to 900rpm when warm, never had any stalling issues since