Engine speed jumps up

[samwise05]

My 280z (EFI) idles at a steady 1000 rpm when at rest, when i start driving however the idle jumps up to 2100 rpm. Its stays high, until i come to a stop then it drops back down to 1000. If I am moving at all the idle is too high!! Help me please

[chickenwafer]

you're not idleing if your moving, so I'm affraid I don't understand what you are saying.......

When you drive for a few minuets, and get to a stop light and come to a complete stop, how is the idle then? If you have your foot on the gas (which would cause you to move) the engine speed is going to increase- that's a given.

Please explain a little more throughly......

Dave

[thehelix112]

Is it an auto?

Dave

[samwise05]

Ok this is what i mean, when i am moving with my foot on the gas all is ok...However if i put in the clutch and its in neutral, the engine speed is at 2100 rmp. when i come to a stop the over rev drops back down to idle at 1000 rmp. So it only happens when i am moving. If i upshift when moving, the car will push until it hits 2100 rpm. So if moving the engine wants to be at 2100!! If anyone can help, it would be wonderful.

[sblake01]

If you have a California car, check the altitude sensor. When they act up, they cause a problem similar to what you are describing.

[dogma420]

fill out your profile information with where you live.

[st0878]

Also look at your BCDD

[Ken]

Check your throttle opener valve setting. There is an adjusting screw that does not let the throttle snap shut when you remove your foot from the accelerator pedal. This is part of the emission control system. This is mounted on the left side of the balance tube and consists of a vacuum control valve which operates the servo diaphram which in turn controls the carburetor throttle valve. If this screw is out of adjustment it will retard throttle return and result in a longer delay for the engine to return to idle speed rpm.

This should solve the problem.

[Ken]

Just noted you have a 280Z EFI! The info I posted is for the 240Z. I don't know if you have a similiar system function on the 280Z.

Sorry....

[chickenwafer]

you're EFI, so it could possibly be the themorstat, but I'm doubting it.

[First Gen Z]

Check the flap in the airflow meter. If it sticks it could cause your problem. A little WD40 will correct the sticking flap.

[dogma420]

How about a completely wasted distributor screwing up advance, etc...

I had a similiar problem to yours, replaced the dist but also adjusted carbs at the same time (something you don't have an issue with)...so I'm not sure what really fixed the idle issue...