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Old 01-11-2013, 03:09 AM   #1
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Default Weird VVT problem OR major loss of power

I have a 02 completely stock miata.

Now once the coolant gauge moves above a little less than 1/4 from cold, i notice power loss.

When the car is cold i can feel what is the best easily described as vtec at about 3500 rpm, even at 10% throttle.

When the car is warm i lose the feel, and in higher rpms, you can really notice loss of power, basically a bad tune, no miss or anything like that.

No CEL or any problems, just lost of power.

I feel its VVT not working, but i dont know why it works when cold but not hot.

Just need some insight.

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Old 01-11-2013, 03:45 AM   #2
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VCTS solenoid issue?

e: Or a clogged cat?
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Old 01-11-2013, 11:02 AM   #3
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Disconnect the VVT plug and go for a drive, see if it is different. (I don't know if it will produce a CEL)
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Old 01-11-2013, 11:35 PM   #4
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What's the mileage and have you ever had a tune up?
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Old 01-12-2013, 10:26 AM   #5
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are you sure your'e LOSING power when it's warm? or you just can't feel the change from super super slow to regular power levels?

The VTCS does work like that. When cold, it closes butterflies up to a certain RPM and then opens and it CAN feel like a woosh.

But when the car is warm, the butterflies are always open. So if you want to test this, you can unplug the VTCS actuator and get the same feeling hot or cold. It may run like **** until it warms up a LITTLE but it will still be a valid test.

I don't have a good picture but it's the wastegate looking thing under the throttle body that attaches to the intake manifold. There's a little green (or green and black?) valve in the vacuum line. You can disconnect it there and plug the side that DOESNT go to the actuator.

Anyway. Try it.
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