S2 Loss of power help please
 

Happy New Year everyone. My 2011 RX8 R3 (S2) has started losing power. It is most noticeable under full throttle where you can feel the car holding back. When it reaches around 7k you feel the power return so it gets better the harder you rev it. Coil packs and leads have been changed as well as spark plugs. The car has done 37k Miles and has an oil change every 6 months or 3,000 miles. At first the problem was intermittent but now it is happening all the time. I have taken some data logs which I have attached if that helps anyone point me in the right direction.

The attached logs show two separate full throttle runs where I am on full throttle in second and third gear.

Thanks for your helps guys :)

https://cimg8.ibsrv.net/gimg/www.rx8...ebae6faeca.jpg
https://cimg9.ibsrv.net/gimg/www.rx8...f0397b6ad6.jpg
https://cimg0.ibsrv.net/gimg/www.rx8...2d995ea24d.jpg

Betting it's the SSV. Make sure it moves freely and the solenoid functions and all of the associated vacuum lines are in good condition.

Is the car stock? I can see your STFT jumping all over the place.
MAF reading seemed low. WOT at redline should go above 200g/s.
And the 600ish min RPM, did the car idle that low or..?
Not an expert on this but I’ll start clean my maf, make sure the screen in the intake(both stock and AEM) is in there and placed properly.
SSV is also possible but that does not really explain why you feel a power come back at 7k.

My thought with SSV is that the APV opens at ~6400 or whatever and it indicates almost 7k on the tach. When my SSV was non-functional it behaved like the issue above.

Definitely worth checking the MAF while investigating the vacuum lines for leaks.

Hello Everyone, thank you all so much for looking at this for me.

DocWalt - Thank you, I will check this valve with a vacuum gauge and let you know.

Shaozhou Zhang - Yes the car is stock. I think it is normal for the STFT to jump around, the long term looks ok to me? I agree the MAF is low. The car idles fine, that was probably just me letting it drop low earlier in the journey when stuck in traffic :) I have ordered a new MAF to eliminate it. I feel a distinct power increase at 7,000 RPM but that doesn't mean the power is coming back fully especially given the low MAF at this rev range.

Trims look fine. MAF looks Okay also, considering you didn't get to redline in the log. Another 800rpm would have put you over 200, and anyway looking at absolutely airflow at speed isn't super useful.

Test the SSV for sure but you said this car only has 37k miles? If it got dirty that quickly I would be curious why. Did you ever have oil in your intake?

Hello, yes i will test the SSV solenoid and vacuum when i get chance. I didn't want to push it too hard while having a problem in case it caused engine damage so that is why I didn't hit the red line. Looking at other peoples MAF logs even at 7500 rpm they are higher than mine.

There is no oil in the intake

Guess what, the SSV is stuck solid. Can hardly even move it with a screwdriver.

See here

Worth a try doing Seafoam or other carbon cleaner down the intake and seeing if that will free it up? Will likely just need to go through the process of pulling it and cleaning it up.

I will remove it and clean it properly then that way I will know that all the carbon has been removed. I should change the FL22 coolant at 10 years anyway so this will be a good excuse to do other jobs :icon_tup:

Hello All, Just thought I would give you an update. The SSV was completely stuck when I tried to remove it. Took ages of working it and WD40 to release then loads of carb cleaner Seafoam and elbow grease to remove all the carbon. Now I am getting 221 g/s airflow at full throttle and the car is back to it's old self :)

Thanks for all your help and advice.

https://cimg1.ibsrv.net/gimg/www.rx8...72da8f99ff.jpg
https://cimg3.ibsrv.net/gimg/www.rx8...e8d7c3aad1.jpg
https://cimg5.ibsrv.net/gimg/www.rx8...8dcf7a763c.jpg
https://cimg7.ibsrv.net/gimg/www.rx8...44fdc50a35.jpg
https://cimg9.ibsrv.net/gimg/www.rx8...850898f104.jpg
https://cimg0.ibsrv.net/gimg/www.rx8...fae4178e68.jpg
https://cimg3.ibsrv.net/gimg/www.rx8...affa7afa52.jpg
https://cimg5.ibsrv.net/gimg/www.rx8...f0adc214c5.jpg
https://cimg6.ibsrv.net/gimg/www.rx8...babee25d9d.jpg

now you can start saving for a new engine ...

Funny you should say that......... I did a compression test today and it doesn't look too good. What do you think?

https://cimg2.ibsrv.net/gimg/www.rx8...39f4408f0e.jpg
Front 38k miles
https://cimg3.ibsrv.net/gimg/www.rx8...0980bbb60f.jpg
Rear 38K miles

I have similar situation probably. I didn't logged data like you did, but I had compression test and dyno test. 2010 R3, got around 190 crank HP on a dyno, with front : 7 - 6.8 - 7.2 and back 6.7 - 6.6 - 6.4. So compression is ok, but the power is not there on the dyno graph. I didn't removed ABS sensor, cause I didn't knew that it should be done. So there's something to look at, but I'm not exactly sure what (yet). Here you have a chart, might help you out to understand the results. Mandatory Compression Test

Its surprising that at 38k your SSV is jammed and compression is down. Are you sure it's actually 38k?

That’s a lot of carbon for only 38k.

time for Italian tune up and couple gallons of water through the engine to shake things up. if it does not improve start saving for rebuild

Can you post your Dyno graph so we can see please? If you watch this video around 7:48 this car has a stuck SSV and you can see the strange power curve it is producing.


Just like when mine was stuck the power does recover near 7,000 RPM but never recovers to what it should be pushing out

Yes 100% correct mileage. I bought the car 6 years ago at 19k miles but the previous owner had been using fully synthetic oil so a possible cause? I use the car as a daily driver to work which is 4.5 miles away so total of 9 miles a day but weekends I take it out and Red line it wherever I can. Here are my fuel stats over the past 5 years https://www.fuelly.com/car/mazda/rx-...type_uk/415056

My previous RX8 I bought from new and I did 30k in it without any of these problems yet driving the same route. The compression on that previous car was still in the high 7's. And before you ask why did I replace that car I had no choice because it was in an incident and was an insurance write-off :(

I was thinking the exact same thing. I was looking at getting a Micro mist irrigation water jet and spraying a fine mist into the intake for 15 minutes at a time and see if the compression improves. Do you know anyone who has done this and has maybe done a video or guide?

Interesting. Mine dyno graph looks like this:

https://cimg9.ibsrv.net/gimg/www.rx8...9e91a24c97.png
Dyno RX8 R3

yes there is plenty youtube videos on how to, just search rx8 seafom. run gallon of distilled water via vacuum hose on the lover intake manifold one rotor at the time

Very much looks the same with a dip in the power instead of a constant climb. I would check if your SSV is free by connecting a mityvac to it and checking if it moves. If it does then check the SSV solenoid as they did in the video.