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Rolling Idle On Start Up?


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Hi peeps,

my 93 SC400 every now and then and at least once a day will idle upto 1700 rpm and then down then up... several times before finally settling down.

I have done a vacuum hose check and changed the idle valve.

Any help would be appreciated .

Thanks,

Rafiqi.

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Don't know if this helps at all but on my 97 SC300, in the mornings when I go to work and the car has sat all night, the RPM's run high, between 1 and 2k until the car starts getting warm. If you take off immediately its a high enough idle to roll the car. I think it just does that to warm the engine quicker. Simple solution: Let the car warm up for a few minutes before driving. That's what I do anyway..

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Don't know if this helps at all but on my 97 SC300, in the mornings when I go to work and the car has sat all night, the RPM's run high, between 1 and 2k until the car starts getting warm. If you take off immediately its a high enough idle to roll the car. I think it just does that to warm the engine quicker. Simple solution: Let the car warm up for a few minutes before driving. That's what I do anyway..

You're right. This is normal. It's similar to the old manual choke. You can drive off after less than a minute except in the winter. I let it warm up until the revs come down to 800 or so before driving off. Less stress on the tranny and gives all the fluids a chance to pressurize throughout.

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Mine idles up and then down and then and so forth for about 20 cycles.

I don't think this by design.

Don't know if this helps at all but on my 97 SC300, in the mornings when I go to work and the car has sat all night, the RPM's run high, between 1 and 2k until the car starts getting warm. If you take off immediately its a high enough idle to roll the car. I think it just does that to warm the engine quicker. Simple solution: Let the car warm up for a few minutes before driving. That's what I do anyway..

You're right. This is normal. It's similar to the old manual choke. You can drive off after less than a minute except in the winter. I let it warm up until the revs come down to 800 or so before driving off. Less stress on the tranny and gives all the fluids a chance to pressurize throughout.

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Mine idles up and then down and then and so forth for about 20 cycles.

I don't think this by design.

Sounds like a typical vacuum leak somewhere between your TB and intake manifold.

Some other parts that could be starting to fail: cold start injector, coolant temp sensor, IC motor.

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