Hi guys
Had my 2003 stock std rx8 on my own dyno this weekend.
My car was feeling low on power since I bought it in Nov 2007.
So I started browsing the net and this Forum for any info.
So far the only thing that might make sense is coils.
The car has 86000 km on the clock and in very good condition.
I'm the second owner and the car's got full service history. (contact the mazda service deparment).
Mazda says there is nothing wrong with my car and there is also no fault codes.
Did a ECU reset and had a small improvement in midrange.
It's a 6 speed. The dyno is a Dastek dyno. On enertia run the car made a little less hp.
When driving the car it feels as if it struggles to get some air into the motor from 6000 rpm upwards.
I checked at the engine that the SSV actuator and the VDI actuator opens at WOT on the dyno.
Could not check the APV motor for operation. I do not think that the APV itself would make such a big diff.

So all I got out the car was 97rwkw(131.08 rwhp) while braking the dyno at 8200 rpm.(3rd gear and also 4th)

Checked the AF ratio's :
Idle - 15.2
Mid - 13.8
WOT - 12.8

I made about 6 runs to verify.

Any ideas.

 

the AF sounds about right.

but u might want to check ur coil for failure. They will not throw any code unless its completely dead.

 

If you could post the dyno graph, we could see if the valve changeover points are looking o.k.

S

 

I didn't print the graph but i did check it with other graphs from the forum and my car does not have the dips in the graph. Although the actuators did operate each on its own as the revs went up to 8500. Could also hear the engine tone change.
Will do another few runs this weekend and save the graph.

 

Here's the issue I've been fighting

Summary:
2004 6MT: Build date March 2004: 125,000 km: Starts well, Runs well, smooth idle, average MPG, no CEL, normal oil consumption, All recalls done

Low HP on Dyno day. MM said that the MAF max flow was low.
Charted MAF readings against a healthy RX-8: the flow diverges over 6000 RPM
Pulled Cat - no difference
Cleaned MAF, TB and changed air filter. Checked TB operation. - no difference
Vacuum tested the VDI and SSV actuators - working - linkages move freely.
Removed VFAD crap after finding a vacuum leak. - no difference (VFAD was jammed open)
Seafoamed - no difference
Verified APV motor working (self test).

We ran the engine RPMs up to 6K with no observed movement of SSV actuator... Does this need load to operate?

Supposition
The AFR stays rich so we do not suspect the fuel pump
Starting and idle are very good so we think compression is good

Not verified
Air solenoids under UIM for SSV, VDI
UIM internals (VDI, SSV)
LIM internals (APVs)

 

Rotorbug - Along the lines of where DarkBrew was thinking check your VFAD for a leak. Easiest way to do that would be to remove the VFAD hose and cap it off and see if the issue goes away. Other then that I would be going with nycgps and thinking plugs or coils.

DarkBrew - When we were working on Vyn's SSV a while back we saw the same thing with the SSV. The car needs to be in gear for it to open for some reason. However, if you take a pump you can get the SSV to move and as long as it moves freely it should open under load. You should also feel the point when it opens as your torque jumps.

 

Well, you can check the dyno chart and AP data logs in my previous post...
There is activity but I wouldn't say torque jumps...

 

I guess "jumps" is a bad word to describe it. As each port opens though I can feel my car pull more and the sound does change.

 

Well I eventually found the problem with my car.
It's called : Mazda made a boo boo!
Bad boys! The Renesis in my car went bey bey.
No 2 rotor apex seal broke and destroyed the rest. This was in morning traffic!

See the replacement here:https://www.rx8club.com/series-i-major-horsepower-upgrades-93/series-5-rx7-turbo-into-rx8-197699/

 

We nailed down my problem
After systematically checking everything on the list I narrowed it down to a small vacuum leak on the SSV actuator. It drained to half vacuum on the gauge in 5 seconds.
I sourced a working SSV actuator and recently installed it.
On the AP data chart you can see the before and after air flow reading.