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Hi everyone, good to be part of the community!
I got my '05 Titanium Gray about a year ago and am still in love with it (ofcourse..)
After expierincing some power loss at low rpm (maybe vacuum leak) i first of all went to do a compression test at a certified mazda mechanic. He was well aware that the rx8 is plagued with low compression (im at 82k), i asume he was familair with the procedure as i saw the instructions provided by mazda on a printout. It's just that i cant make anything of what he gave me, there's no ' three phases' and no rpm values shown...
probably shouldnt have picked up my car so hastly, and il most likely go back for some info -.-
The worst symptoms im expierincing is that the engine is hardly responding to the gas pedal when really hot (45 min drive), the revs go up like crazy but car hardly moves forward. I gotta press the gas pedal really little to match my rpm to my speed. Once i press the pedal down further the rpm goes up, as speed stay same.. it happens in any gear. What drives me crazy is that when cold or even hot (30 min drive) the engine respond really well to the gas pedal with a good low end power.
Il probably be replacing both CAT, fuelpump and radiator (fans dont stay on after shut off...) next month.
Let me ask a few questions first.
1.is the car manuel or auto. The reason i ask is it does kinda sound like a bad clutch ir the rpms are moving and the car isnt.
2. Are you having any problens starting the car. Whether it is hot or cold.
The compression chart your service agent is using is for a normal piston engine and will not give you the three compression readings for each chamber on each rotor. He gave you two and I don't see a peak (tangent line at zero slope). The motormeter is a great tool - I have used these on processing equipment for maintenance checks on performance.
You will need to have a Mazda rotary compression test done at a dealer.
It looks like he measured each spark plug... there are 4 lines.. that's not filling me with confidence about his understanding of these engines. It's not wrong..but why would you do that?
On the bright side, he measured 9.5bar on rotor 2, which is better than a brand new engine... so.. there's that. Think you might want to get your money back and try somewhere properly equipped.
And the guys above are right, if the rpms change but the speed doesn't, the engine is no longer connected to the wheels, so there is a clutch problem.
Its manual 5 shift. Guess il be giving them call next week.
Im descrbibing two different problems btw, the low end power loss is felt always (also with cold engine) and doesnt really bother me to much (many pistons only get alot speed at higher rpm anyway).
The power loss when hot (rpm moves with gas pedal, speed doesnt) is really disturbing though..
If the clutch was bad wouldnt it also be with a cold engine?
Yes hot starting doesnt go smooth, but hasnt failed me yet, alrdy have new starter, plugs, coils and leads.
Also past weeks cleaned some oil out of the intake, cleaned MAF, cleaned Throttle body.
Maybe its a mix of low compression with bad full pump (il get my fuel pressure tested aswell).
EDIT: yea i see now it appears he measured each spark plug.. the B stands for Above and O stands for Below i believe.
Ok, so i went back to the Mazda certified mechanic... he keep persitting he did things right... i payed 100 bucks for a test of wich i cant use the results..
First he says the O and B stand for chambers (yes he claims to have measured two chambers), then his college sais they stand for the Plugs.. i told him you dont need to measure both leading and trailing but just either of those. They said that a couple weeks ago someone else came in for a compression test with an rx8, they measured bad compression with same test (motometer). They keep insisting my compression is good. I told them they measured 9 bar, wich is higher then a new engine, they replied: The only important thing is the Psi (bar) difference between the two rotors.
They have no idea on what rpm they measured and say it was the starting rpm..
now get this, i called Mazda in my country. They refuse to do a compression test. They claim they dont have the equipment/knowlage... im stunned...
I think im gonna buy a tester and do it myself... (not sure, its the 'anger' speaking)
There is a DIY here for making your own tester for 85 bucks. But yes, the mechanics can continue to insist but they have no clue. I don't think they understand how the engine works. Mazda has a clear guideline for what is expected from a compression test, it's in the RX8 shop manual, you can find it on foxed.ca. Since you didn't receive that, they wasted your time and money. At least money can be gotten back.
Buy a rotary compression tester. Use it. Keep it around forever, charge your buddies a couple bucks to use it or learn how to use it and offer to charge to test.
Sorry to jack your thread but this is my first time being on here and im not entirely sure how to make my own. I was just hoping some one could help me interept my compression test results. Im trying to figure out if i just need to replace the my starter or if my engine is shot and its time for a rebuild.
The Mazda tech pretty much said rotor 2 is on its last legs but from what i understand. Youre supposed to normalize results to 250 rpm. So is it still bad compression and if not does this just mean i need a new starter?<br/>
You can basicly normalize urself using some math with percentage.
Kgf/cm2 almost equals bar, the minimum u should have at 220 RPM is like 6,1 Bar.
The 6,9 minimum on the right side is matched to 250 rpm.
Edit: You should make a seperate thread to get more replies, also you can try to decarb and see if compression results will increase. Personally i would do a revision once the engine is really near dead instead of still being above minimum.
12-02-2016, 01:32 PM
