Anyone had this happen to them before?

The TB seems to be working fine when operated manually. And low'ish boost I can't make it stick. But on high boost it sticks pretty bad.. reving for another second or so.

I'm thinking it's possible the flow of air over the plate is actually overwhelming the return spring? I've been told to try to wind the spring around one more time if possible.

Any input guys?

 

I am not so sure that the plate is actually sticking. There have been many people who experienced hanging rpm's. This would mean they let of the throttle but RPM would literally hang at high rpm for a second or two.

This was most common on the Evo IX and there was some tuning work that people did to try and cure it. I never had the problem so I don't really know how to fix it, but if you search in the ECUFlash forum for haning rpm you will find the thread where the discuss the issue.

 

https://www.evolutionm.net/forums/sh...d.php?t=226466
https://www.evolutionm.net/forums/sh...d.php?t=108559

 

I had this problem on my VIII I thought it was the clutch... replaced with a ACTand it still did it.... it stopped doing it after about 5000 miles or so?

 

Very nice of you guys to kick off those replies... but unfortunately I don't think they apply to me cuz I'm on Autronic.

 

Is it theoretically possible that significant airflow could keep the plate open if the return spring had gotten tired (like a 1999 throttle body).

 

FWIW I wrapped the throttle plate return spring around one more time and this solved the problem. So I presume this does mean the airflow was keeping the plate open to some extent.

 

1/2 the airflow would be trying to close the plate, while the other 1/2 would be trying to open (or make it hang open) the plate. Cancelling themselves out. Since the throttle plate rotates on a shaft in the center, the leading edge of the throttle plate will be trying to force it closed, while the trailing edge would be trying to keep it open. I don't think excess airflow is your problem.

 

I hear what your saying... I'm just glad it's fixed.

The fact it did not behave like that on low'ish boost made me think it must be the airflow. My throttle body is mounted upside down, doubt if that makes a difference.

 

This may make it bind. Just replace the old parts

Your diverter valve might be staying closed too long also

 

I really don't see how wrapping a spring around one more time could cause any problem. The thing is wound around dozens of times already.