WHY???when I start my car is the idle is over 1500 rpms constant!

[Q45CALIBER]

Every morning now when I auto start my car and let it warm up it races like crazy. The idle stays high. If put it in drive I can still tell it is racing when I brake and come to a stop. If I shift into netural the rpms fly up over 1500.

What the hell is causing this??? There is not fluctuation it just races at a constant 1700 rpm.

[Q45CALIBER]

Does this sound like 02 sensors. Its driving me crazy! The engine light is not on. No sure if it would should any codes. I know this car does not like the cold....Has any one had this problem. Read post in the past that were similar issues.

[Q_SHIP]

How is it after the car warms up? Deos it come back down?

[zinkie13]

My car always starts out idling higher too. It also revs higher in the gears under normal acceleration when it is warming up. I always just thought it was what the car did to help itself warm up faster.

[Q45CALIBER]

How is it after the car warms up? Deos it come back down?

After it is warm it will stay high.

[Q45tech]

Since 90% of an engines pollution occurs during the first few minutes of crank and warm up of the combustion chamber until the intake from injectors thru heads and thru values come up to a stablized temperature [174F] to optimal vaporize the gasoline squirted from the injectors.

And the catayltic convertors don't work until they warm up.

A dual strategy is employed: [a throttle plate opening based on lack of coolant temperature] and ecu controlled addition of air via the IAC.

The rpm is primarily a function of coolant temp coldness.

Around 120F coolant temperature the mechanical hot wax throttle opener disengages and the ecu uses IAC totally.

Oil really doesn't lubricate very well until it get up to at least 100F [actually it's pretty bad til 140F] and the transmission ATF is too thick until roughly the same temperature. The transmission protects itself by avoid overdrive [4th gear] until it's warm.

For maximal longevity one would let the engineers do their preprogrammed things and warm the car in place until the coolant temp starts to rise into a safer region [5 minutes]. This is wasteful of fuel as you get zero miles per gallon but prolongs the engine/transmission life.

Everytime you crank a cold engine you are probably creating more stress than driving 100 miles at 60 miles per hour..........without multiple daily cold cranks engines would last A MILLION MILES+ as proven by BMW and Mobil 1 on their continuous track test [only shutting down for the oil changes and maintenance.........they ran 24 hours per day with 6 drivers per day!

A significant problem is the cold diffential fluid which takes driving to warm up................why one would chose a premium synthetic over conventional or put up with less than 200,000 mile life.

[Q45tech]

Another problem is misadjusting of the IAC manual air bypass around the ecu controlled electronic valve.............by shade trees to adjust the idle speed instead of fixing/cleaning the problem.

A worse situation is adjusting the sealed screws on the throttle body that set the hot wax lift and taperdown positions......requiring a new unit to get it back to as designed.......no way to reset without cold weather [coolant]and days and days and days of fiddling and it is never right again.

[Q45CALIBER]

Thank you for the post. I am not sure it helps although it was informative. I warm my car up before I drive it everytime to avoid engine and transmission failure. I run Mobile syn 5w 30. Syn trany fluid. Lucas in the diff., and engine.

This is probally the only car I have had that I baby and make sure the temp gauge has moved between the H and C before driving.

However at this point the car can be warm and driven for 20 minutes or more and still be racing. I need to find what component is malfunctioning.

[squeefoo]

Thank you for the post. I am not sure it helps although it was informative.

How can anyone help you? It is impossible to give even a rudimentary diagnosis without any understanding of what you have/haven't done yourself to diagnose this. This Q45 is a very complex system and an answer cannot be divined via a question or complaint. Quote »I need to find what component is malfunctioning.[/quote]All we know is the idle stays high when hot and there is no CEL, how would you answer that?

What have you looked at or done or tested? ....assuming the engine was running as it should to begin with.

[elwesso]

hes right, unfortunately the Q45 doesnt sport the button under the hood that you simply press to fix problem... Wouldnt that be cool, they have a 1 page FSM.. "if a problem occurs, open hood, press red button to fix problem, close hood"...

Id check the IAC first.... and for a vacuum leak

[Jesda]

Thank you for the post. I am not sure it helps although it was informative.

There's something amusing about that. Welcome to the Dennis Experience.

[squeefoo]

hes right, unfortunately the Q45 doesnt sport the button under the hood that you simply press to fix problem... Wouldnt that be cool, they have a 1 page FSM.. "if a problem occurs, open hood, press red button to fix problem, close hood"...

Id check the IAC first.... and for a vacuum leak

...sounds like the NICO "easy button"

[Q45tech]

Obviously a 1500 rpm warmed up idle means more than standard air entering the engine, because the IAC is mostly a positive air adder and has little leeway to decrease the air flow [10-15% if set perfectly].

Common things overlooked are accidentally or otherwise removing the designed in slack from the cable to the TB and misadjusted IAC manual air bypass.......it should be screwed all the way in then 2.5-3.0-3.5 turns out from bottom.

[maxnix]

Really, it is very kind of Q45tech to repeat himself for the 13th time, but this is all covered in the previous posts.

Please read them.

[nchopp]

There's something amusing about that. Welcome to the Dennis Experience.

Bwa ha ha, "The Dennis Experience". It should be a ride at Disney or something.

[Q45CALIBER]

How can anyone help you? It is impossible to give even a rudimentary diagnosis without any understanding of what you have/haven't done yourself to diagnose this. This Q45 is a very complex system and an answer cannot be divined via a question or complaint.

All we know is the idle stays high when hot and there is no CEL, how would you answer that?

What have you looked at or done or tested? ....assuming the engine was running as it should to begin with.

Squeefoo - you are right.

Here are the parts and things that have be changed this summer not including supension items: Knock SensorsMAFNew Plugs NGK w/PCVWater Pump w/flushEngine Flush- I run Mobile Syn 5w 30Tranny Flush at the dealerDiff Flush New Fuel Pump & Filter w/coolant flushNew AltenatorNew Starter

Maybe this helps.

[Q45CALIBER]

Note taken. However I did search and was not sucessful. Probally wrong key words. I will check the IAC.
Modified by Q45CALIBER at 1:31 AM 1/1/2006

[Q45CALIBER]

Can someone direct me to the ICA. Only found to post on it but I would knoe where to look for it.

Does this go bad after 120 or so miles generally. It is a damn expensive part 300 plus ouch!

[Raxephon]

On a Q45 its actually called an AAC Valve, basicly the same as an IACV.(Auxiliary Air Cointrol)

zerothread?id=33796

[Raxephon]

[Raxephon]

And one more from the thread that I posted a link to above.

[Q45CALIBER]

Thanks for the picture post.......that is extremely helpful. I have a old Q in the back yard I am going to swap the part. If that does not work I will buy new one. Thanks

[squeefoo]

Thanks for the picture post.......that is extremely helpful. I have a old Q in the back yard I am going to swap the part. If that does not work I will buy new one. Thanks

Before you switch it over, clean it out as good as you can (i.e. toothbrush, brake cleaner, ) after taking it apart as much as you can. Hopefully one of your gaskets will survive being dried out from thermal cycling and smashed into place for so long. I use Permatex Hylomar HPF for sealant since you can re-use it, and it doesn't actually glue anything on -Just seals.

As long as you are working on it -clean out your Throttle Body (TB) and clean as above (the areas around the butterfly) don't fill the plenum with solvent and slime, or it will flood and start like Shyte, if at all.

Check for codes, and check your timing.

[elwesso]

Actualyl I like using oven cleaner, juts be sure to rinse it out real quick after and dry thoroughly!!