RPM

[Colin Francis]

My MX5 usually idles at about 700 to 800 RPM. Whilst driving and pulling to a
stop the RPM drops to about 1500 and then over a few seconds slowly drops to
700- 800 rpm. (AC is off) Has anyone any idea why the slow return to idling
speed when stopped ?

TIA


[...]

[cyhegley]

Col

I have had a similar problem with my work van. Found it to be a combination
of a dirty Accelerator cable and throttle body assembly where accelerator
cable attaches.Clean them an it should return to normal. I found CRC silicon
spray works well.

Stu

[Colin Francis]

On Wed, 14 Apr 2004 20:19:51 +1200, you wrote:

Col

I have had a similar problem with my work van. Found it to be a combination
of a dirty Accelerator cable and throttle body assembly where accelerator
cable attaches.Clean them an it should return to normal. I found CRC silicon
spray works well.

Stu

Thanks Stu. I'll try that.

[Colin Francis]

On Wed, 14 Apr 2004 20:19:51 +1200, you wrote:

Col

I have had a similar problem with my work van. Found it to be a combination
of a dirty Accelerator cable and throttle body assembly where accelerator
cable attaches.Clean them an it should return to normal. I found CRC silicon
spray works well.

Stu

Looked at that . The 1800 motor is controlled electronically.

Symptom

On stopping the RPM counter drops to 1200- 1500 RPM for 6 or 7 seconds then
slowly drops to 750-800 (my normal idle speed ).


Any comments ?



[...]

[SLYDIT]

There are two possible causes.
1) your throttle damping valve is incorrectly
adjusted.(it looks like a gold diaphram assembly with
a rod that touches the accelerator linkage. its sort
of a shock absorber that softens the transition to the
closed position..If its adjusted so it comes in to
early then you accelerator wiil be slow to re seat
back to idle position. operate your throttle body
linkage by hand to rev the engine and watch what happens when you let it go.
The other possible cause is that your idle control
valve may have carbon deposits in it and needs
cleaning out. youll need to take off your ntake pipe
just before the throttke body, and spray it with
cleaner. Also clean around the main throttle body
butterfly with a CLEAN rag while your there.

[Colin Francis]

On Thu, 15 Apr 2004 05:56:28 +0100 (BST), you wrote:

There are two possible causes.
1) your throttle damping valve is incorrectly
adjusted.(it looks like a gold diaphram assembly with
a rod that touches the accelerator linkage. its sort
of a shock absorber that softens the transition to the
closed position..If its adjusted so it comes in to
early then you accelerator wiil be slow to re seat
back to idle position. operate your throttle body
linkage by hand to rev the engine and watch what
happens when you let it go.
The other possible cause is that your idle control
valve may have carbon deposits in it and needs
cleaning out. youll need to take off your ntake pipe
just before the throttke body, and spray it with
cleaner. Also clean around the main throttle body
butterfly with a CLEAN rag while your there.

Thanks Glenn . I will look at those .



[...]