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Discussion Starter · #1 ·
I was curious as to what is the RPM at idle for the QP. I ask because it seems to vary which I would expect depending on whether AC is running etc. However I have noticed something which I can't explain.:confused:

The background is that as per previous posts, I will occasionally shift into neutral and coast / brake when arriving at a stop light or sign. Let us ignore for the moment whether this is advisable or not e.g. does it prolong clutch life or is it safe. When I do this the car comes to a stop with an RPM of 1000. If while at a stop and in neutral I tap the gas, it drops to 800. Is there an explanation for this? And / or what is the specified idle RPM for the 4.2L engine? Is this set by the mechanic or does the ECU "dial" it in?
 

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Mine is a 2006 QP, the idle RPM is between 750 to 1000, it is not the same all the time and sometimes at 750 you can feel the vibration from the motor. I wonder if someone knows what the specs are for this engine, but as far as I remember all italian cars never had a set number and the RPM always "moves" a little.With other cars it is at a set number and never moves from that number.
 

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750 to 1000 RPM under all conditions is perfect. 750-800 RPM HOT idle w/o AC. 800-850 RPM W/ AC. 900-1000 Coldstart. 1000 _+ RPM idle between gearshifts ,so not to stall.
Coasting in nuetral EXTENDS clutch life.
Adjusted solely by Engine control unit.
Yours sounds great.
Have fun--Kent
 

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What he said...

The ECM will vary idle RPM based on atmospheric conditions and the state of the transmission (safeguard - guessing what you're going to do next ) as Mr. Woodworth has noted, nothing to worry about, you're A-OK!
 

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Discussion Starter · #5 ·
What exactly is ECU thinking?

Thank you for the explanations. It sounds as if all is well with my RPM. Still interested to know WHY that if I let the car downshift on its own it comes to rest at 700-800RPM where as if I coast to stop it only drops to 1000. What is ECU anticipating that it would "want" to under the coasting situation maintain a higher RPM?
 

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It's actually coming from the TCU, it believes that it will need to shift into gear shortly. After all it's in neutral, that's really the only other place to go unless the engine completely turns off. When the car shifts down on it's own, it's in gear and when you're coasting down in neutral the engine is not expected to be at rest.

Hope that helps.

-- Jeff
 

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NON QP's ?

What's the correct idle for Coupe/GS ? My '02 is steady at 1000 (ever since changing the plugs) but most cars idle - when warm - somewhere around 600-800.
 

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My GS starts at 1250 in the morning and drops to 1000 after warms up. I don't think it ever goes below 1000... I'll confirm it tomorrow.
 

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My 2003 Coupe starts out at around 1250 cold and then settles in at 1000 as well.
 

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Just checked, it does idle at around 800-900 rpm when warmed up.
 

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Idle speed

My 04 Coupe usually idles around 1000 after warming up. However, the speedo only goes down to 10mph. I guess there are those cars that look like they are moving when standing still. Mine even shows it on the speedo. Anyone know how to adjust??
 
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