Diablo Idle RPM ......

[TonyAM66]

Hi All,

I would be interested in other owners comments on their Diablo (5.7 ltr) Idle RPM speeds.

Mainly due to time constraints and partly due to a flat battery (I have Optimate Chargers but just hadn't connected one!) having charged the battery over night, this morning I started the Diablo for the first time since it arrived (1st week in Feb.)

Idle RPM when cold were 2,000 which seemed a little high?? ..... I would have thought c1,500 -1,700 RPM more the 'norm'? and then settling to c1,100 -1,200 ish RPM when warmed-up ??

I was wondering if in owners experience the Idle RPM is slightly high at 2,000 RPM when cold or is it the 'norm' ?or if owners find idle speed tends to be higher if the car has stood and not been started for a longer period of time, especially if the battery has completely discharged and had to be charged ahead of starting?

I let the car run for c3-4 minutes and the engine speed did not slow from 2,000 RPM so with that and the phone ringing I shut it off......

Any thoughts?

T

[dwndraft]

Normal.

A cold Diablo will idle high for quite a while, and even roll the rpms up and down from all most stalling to 2000rpms if left for a while not driven. There is a carter motor that is controlled by the LIE that does it all mechanically. The functions is to calibrate the LIE, I believe.

I love it, pretty dramatic and super car like.

[037]

This type of question and answer is the reason I read Pistonheads.

[Ferruccio]

Switch and then leave it.
The RPM will go up and down for 3-4 minutes until it warms up a bit and settles down.

[TonyAM66]

Great Stuff! ... Thanks Chaps!

T

[George 500]

Yup- don't worry about it

Mine takes as long as 10 miles/20 minutes to come down from around 2100

It slowly dips to around 1,700 and then idles at just over 1,000 when fully warm.

It does this whether I haven't driven it for the winter or since the day before- just a quirk one has to get used to (if a slightly embarrassing one through town...!)

[TonyAM66]

Thanks for that George

[Davo456gt]

carter motor is only on later model cars (98 VVT onwards I believe).
earlier cars have an air valve near the thermostat group.
Both operate until the engine temperature reaches 70 deg C.

My 99 with carter motor, does 2000 rpm for about 5 minutes, then drops to around 1100.

[auyt]

I just read with interest this thread and the reference to Carter sparked my interest is the reference to the injection system?

[Davo456gt]

auyt said:

I just read with interest this thread and the reference to Carter sparked my interest is the reference to the injection system?

Carter motor is basically a solenoid that pushes the throttle bar when the car is cold.

see here..

http://www.lamboweb.com/Repairs_Section/Diablo_Rep...

The "Carter Motor" is a servo motor that sits on top of the engine and adjusts the throttle when the engine is cold. It is controlled by a separate controller unit that is situated beside the LIE computer (but is not part of it). The reason it is called a "Carter Motor" is that it is a servo motor made by a large manufacture of server motors called "Carter".
The operating strategy of this device is co-related to the time that passes from engine ignition and the different temperatures picked up by the engine control sensors. The carter motor uses these parameters to bring the accelerator opening to a calculated value. This decreases as time passes, and the accelerator control is released when the engine reaches the correct rpm. If this motor fails, you will get a "L-check engine " light, an OBDII reading "Random Misfire" as well as difficulties keeping the engine turning over at low RPM's when it is cold.

[auyt]

Thank you it’s a terminology thing, so a carter motor is what I know as as an idle air adjuster but does more across the temp and engine rpm range.

I would like to get an early Murciélago and am reading to learn.