Fast Idle- Bell And Colvil 140 k-series

[daved]

I have recently bought an B&C S1 Elise. In general the car is very nice althugh it does seem to idle a little fast and at times feels like you are driving an older car with the choke on-car is pulling without little or no throttle.

Does anyone have experience of car with similar mods (exhaust, air filter and management chip)? Is this behaviour typical? If not any suggestions?

Thanks

[tut]

Dave, could be just as simple as ensuring that your butterfly is shutting completely, ie adjust your throttle cable at the throttle body, and/or the idle adjustment screw.

The B&C 140 has a standard ECU with a modified daughter board that alters the ignition and fuelling, but is a closed box and non adjustable.

tut

[Shug]

Or a sticky Idle Air Control Valve - plugged into the middle top of the plenum, with a cable. You can remove (torx screws) and clean it with carb cleaner if it's mucky (and it could very well be if you have a foam/cotton filter that perhaps hasn't been cleaned as often as it should.)

[Matelotman]

That's my old car you have there - was never an issue before so it's probably as described above with something needing cleaned etc (if you need anymore background on the car give me a shout)

[fd]

You should NOT change the setting of the throttle body base setting screw . . . it has a tamper proof cover for a reason . . .

If it idled before something else will be causing it, IACV or sticking throttle/cable . . .

dicking with the base adjustment screw merely causes problems for the IACV/ECU . . .

Fd

[robin]

Air leak into inlet manifold is also a possibility - on the plastic inlet plenum the inlet gasket can fail (and there is then also a risk of ingesting coolant into the engine).

Distorted or swollen throttle body is a likely contender, especially if some dodgy 3rd party intake system has been fitted with a jubilee clip.

If you can get it to hold the "fast" idle in neutral you can pop the boot open and grab the throttle quadrant and rotate it anti-clockwise firmly; if the idle returns to normal then your throttle is sticking and this might be caused by poor throttle cable adjustment or the butterfly sticking in the throat of the throttle.

If that doesn't stop the fast idle then an air leak or a sticky IACV is next most likely; if you remove the intake pipe and place your hand over the throttle body intake you should stall the engine; if it keeps idling (especially at reasonable idle speed) then you have an air leak; if it stalls, chances are you have a sticking IACV.

Cheers,
Robin

[alicrozier]

Sticky IACV can also cause a fast idle another way (but can be much higher, I've had 4K+ rpm).
With the IACV stuck shut as the throttle is closing a vacuum is pulled in the inlet manifold and this can jam the throttle butterfly slightly open. Easy check is if the throttle closed position is different with engine on/off.

I had this on a K series 111S so alu throttle body.

[tut]

Could also be that it had a woman driver, so was never revved above 3,000.



tut

[donnac]

Could also be that it had a woman driver, so was never revved above 3,000.



tut

I didnt use the car often to be fair so it could be that