power surge went from 4800 to 6800 rpm
 

2006 RX8 Shinka
Up until I had the car worked on by the dealer for a bad emision system valve which was under warranty, under max acceleration the car would have an increase in power at 4800 rpm. After the dealer it now doesn't have the increase in power until 6800 rpm. Can anybody tell me how to fix this. Does anybody know of a good RX8 mechanic in the Houston TX area, particularly in the SW part?
Thanks

Please be more specific on what the dealership did. Did they replace any parts?

There are two valves in the intake manifold. Both are ECU monitored / controlled - so would've thrown a CEL.

One (the APV) is an electrically-driven motor, the SSV is a vacuum damper. Both of these affect the powerband.

The APV I think opens at 7,200 rpm. The SSV opens at about the same time as the secondary fuel injectors start going (depending on engine load; between 3,200 and 5,500 rpm).

Did you have the car before this fix? (are you the original owner?). If not, I think what you are feeling now is the Zoom Zoom of the APV actually working properly.

You could do a search for: "APV" and "SSV"

things done by dealer
 

one dealer replaced purge solenoid valve
second dealer replaced solenoid valve again

I'm not entirely sure, and I'll wait to be corrected, but I don't think the purge solenoid valve being stuck would have anything to do with the engine powerband noticeably changing at high revs under load (ie:not in vacuum).

However, two failures of that same part in short succession leads me to think that there may be other problems going on.

I am the original owner. The first dealer replaced the purge solenoid valve. The second dealer paperwork only says replaced solenoid valve. Accoding to the second dealer, the first dealer broke a vacume fitting upon instalation on the first solenoid valve that they installed. The check engine light came on again and when I tried to schedule an appointment with the first dealer they could not get to it right away so I went to second dealer which is close by and they changed the solenoid valve. When I picked up the car, the customer rep told me about what they thought occured at the first dealer. Would a vacuum leak cause the difference in performance? Would that not be detected during computer analysis. I took the car back to the second dealer and rode in the car with the maintenance manager driving it and he said that the computer checks out OK and that the car drives normal. I would like to hook up with a good RX8 mechanic and get his opinion. Thanks for your comments so far and I'm open to more.

i bet you were missing power before below 4800 which is why it felt like a surge. now that its fixed you get the normal surge from the intake opening at 6500

Any good RX8 mechanics in Houston TX
 

The car felt like it had more power from 4500 rpm to 6800 rpm or so than it has now and the transition of power was smoother. Also, when I let off the accelerator just a bit when it goes past 7000 rpm or so, sometimes it misses a little. Any good mechanic in Houston TX recommendations preferably downtown, medical center, SW side?
Thanks for your comments

The car felt like it had more power from 4500 rpm to 6800 rpm or so than it has now and the transition of power was smoother. Also, when I let off the accelerator just a bit when it goes past 7000 rpm or so, sometimes it misses a little. Any good mechanic in Houston TX recommendations preferably downtown, medical center, SW side?

Thanks for your comments

You will fee the bggest "surge" at about 6500rpm when the last set of injectors kick in