S1 Exige idles at 3000 rpm

[Sandy]

Car just started doing this in the last few days, starts normally, idles at around 1500 then as soon as I have used any throttle it idles at 3000 and stays there. Last week it was completely the opposite, when warm it was stalling every time I dipped the clutch. Anybody have any suggestions, apart from getting a honda conversion?

[Noops]

Car just started doing this in the last few days, starts normally, idles at around 1500 then as soon as I have used any throttle it idles at 3000 and stays there. Last week it was completely the opposite, when warm it was stalling every time I dipped the clutch. Anybody have any suggestions, apart from getting a honda conversion?

Throttle position sensor?????

[r055]

Idle Air control Valve (IACV) needing a clean?

edit to add:
not sure if there is one on the VHPD, but if there is...

The Idle Air Control Valve (IACV), or stepper motor, allows the electronic control unit (ECU, a.k.a. MEMS) to regulate the airflow to the engine independently of the driver's throttle input.

When the engine is idling MEMS uses this control (in parallel with ignition timing modulation) to compensate for varying loads that the engine must overcome to maintain the desired idle speed (i.e. friction, electrical load, A/C compressor load etc)

The IACV is also used to control airflow during load changes between positive and negative torque to provide a throttle damping function to improve the drivability characteristics of the vehicle.


S1 K-Series engined Elises use a Rover IACV (Part No. MLZ100090)
S2 K-Series engined Elises use a different IACV (Lotus Part No. A117E6069S)

If you are suspiscious that your IACV may be stuck/jammed, you can test it by disconnecting and reconnecting the ECU temperature sender with the car ignition on (but not running). If it can move, you'll hear it chatter as it seeks to a new position when you unplug the sensor.

Contents [hide]
1 Fitting and removal
2 S1
2.1 Location
3 S2
3.1 Location
4 "Resetting" the iacv
5 External links

[edit]Fitting and removal
[edit]S1
Removal is a simple process and takes less than five minutes. It is held in place by two t20 torx screws although a 3mm allen key will also fit. The lower bolt is slightly harder to get at although easy when the IACV is disconnected from the loom. When removed it may be sooty and should be cleaned with carburettor cleaner.

[philthy]

Id check the speed sensor in the rear drivers side hub, can get clogged up with dirt and give false readings or none at all.

Secondly, look for splits in the silicon pipes around the inlet manifold, this is common and makes the car run like a bag of sh*t.

Could be the IACV, but Id try these 2 first before attempting to clean it, its below the airbox-nightmare.

[r055]

Could be the IACV, but Id try these 2 first before attempting to clean it, its below the airbox-nightmare.

The VVC one is very easy to access - hence my suggestion...

Sandy, you could also try the reset procedure which also requires minimum effort.
IIRC - Ignition on, pump gas pedal 9 times, ignition off.

Ross

[robin]

Car just started doing this in the last few days, starts normally, idles at around 1500 then as soon as I have used any throttle it idles at 3000 and stays there. Last week it was completely the opposite, when warm it was stalling every time I dipped the clutch. Anybody have any suggestions, apart from getting a honda conversion?

IIRC there is no IACV on S1 VHPD engine so won't be that. (Just re-read previous post - I stand corrected, there is one but it's PITA to access - in which case it could well be your problem - you can crimp the hose feeding it to see if that stops it).

Most likely the actual throttle itself is sticking or you have a vacuum leak somewhere around the intake manifold/throttle bodies. To get 3,000 RPM it'll be a reasonable amount of air - a careful spray around with an atomiser and some water (you know, the sort of thing you might use to spray leaves of tropical plants) might lead you to the culprit as there will be a distinct change in engine speed/note when you hit the leak with the spray.

To verify it is a leak at all you can try and shut off the air intake (remove the pipe work from the main airbox and put your hand or a rubber stopper of some sort over it).

Cheers,
Robin

[Sandy]

thanks for the quick responses. I will have a go at it today, but I am away for a month as of tomorrow, typical. At least I can try a few things before letting a professional look at it.

[philthy]

I had the same problem but it turned out to be a collapsed inlet manifold gasket (bad fitting) not likely to be your cause but the silicon hoses would create the same symptoms.

to listen for air leaks, I used a peice of hose up to my ear and moved it about the inlet to listen closely for sucking. Random but works a treat!!

[Sandy]

by philthy on Mon Aug 03, 2009 11:55 am

Id check the speed sensor in the rear drivers side hub, can get clogged up with dirt and give false readings or none at all.

First thing I tried. disconnected/cleaned/reconnected and the car is now back to stalling at every opportunity. Now I don't know if I need a new one or if it is now fine and the idle needs adjusting. good call though Phil, thanks.