This might get long, buckle up.

So, I got a 2006 Shinka last month. 35K miles, pretty much a cream puff cosmetically, drove well, no weird noises, ran hard to redline. I wasn't really looking for the car at the time but just ran across it and bought it without all my due diligence as I wasn't really in "car buying mode". No compression test was done before the purchase which was stupid, no excuses. This will be a second car for weekend trips basically, I might put 2K miles a year on it, if that helps. Well, I went to get a compression test just to make sure the engine was solid as I am coming up on my warranty expiration next year and was planning on putting a few grand into reliability mods (ECU flash by RB, BHR catless midpipe and ignition, welded clutch pedal assy, etc) and wanted to make sure I wasn't throwing any money away. The only issue that would have made me think there was any issue with the motor at all is an occasional vibration at idle, not a stall, just a little vibration felt in the shifter and seat as the idle dipped to about 800rpm. Better safe than sorry, went to get a compression test.

What I found out was quite . . . disappointing, let's say.

R1: 729 733 735 actual, 615 619 621 normalized for 250rpm
R2: 551 524 504 actual, 442 415 395 normalized for 250rpm

And this is on a car that starts every time without issue, pulls smoothly to redline with as much gusto as 170whp ought to, sounds great, never misfires or hiccups, doesn't smoke, and hasn't thrown a CEL.

So, a few questions:

1) Any chance these readings are wrong? Dealer says they're confident they are correct, but it seems odd that the car drives so well. I've driven it in anger half a dozen times already (hour long backroad drives) and the temps are rock solid, no hesitation, no weird noises.
2) Without any driveability issues the dealer says I have no claim for a warranty engine despite failing every measure of compression, even fantastically so on R2. Dealer says I should just drive it till something goes wrong. Is this true?
3) If these readings are true, should I expect it to fail completely very soon? If this is a gradual decline that could take 10K miles to manifest power loss and hard starting, that could be five years at the rate I drive it, in which case I'd just drive it till it fails and then maybe look at an engine swap. I've grown to like the rotary, it's quite charming, but not charming enough to rebuild them every 35K miles.

I love the car and would love to keep it, but if it's likely to need a rebuild in the next few thousand miles I may try and unload it ASAP before anything goes sideways, though in that case I'd basically have to prey on another dumb buyer like myself and not disclose the compression test which would make me feel like a douche. I just paid $100 to be told the engine is essentially on borrowed time with no warranty recourse, should I get another test elsewhere or assume it's FUBAR and make a decision accordingly? Thanks for reading if you made it this far.

 

Go back there before your warranty expires and say you are experiencing "driablity" issues like stall at red lights and such and have them replace it.

but b4 u go in, replace all coils/plugs urself.

after they replace it, premix every tank about 1/2 oz to 1 gallon.

be happy and keep the car.


oh btw, there is a slight chance that they did it wrong, cuz the compression is quite low on the rear rotor, with numbers like that, u should experience some issues.


, but whatever it is when my engine failed, it drives fine and pulls ok, just start using more and more gas (11 mpg?) and stalls when it comes to a stop (red light, stop sign/etc)

 

re #2, dealer says you should drive it until something goes wrong, but they tested it and found something is wrong, but its fine.



or actually it makes sense if you stand behind a service desk....


i bought a car with a bad motor, it ran ok, just weak under 2500, and it took a while to hot restart

 

They said until I start having power loss or starting issues I'm SOL. I guess I could start noticing those things? WTF. Shouldn't have to lie if the seals are totally effed. Actually, to be honest, it does start *kinda* hard but I don't want the engine to be toast so I take care not to aggravate it and it never fails to start. And how do they even determine loss of power? Basically my word, no? Unless they put it on a dyno or something.

 

If they wanted to credit me the cost of a reman I'd be happy to buy my own Mazmart rebuild and install it myself, sure that'd go over well . . .

 

Any chance any ancillary systems like the ignition or cat would have any bearing on the results?

 

maybe they will have someone drive it? with mine, i walked in and said, "it has a hard time starting hot, i think the engine is bad"

so they went thru the test procedure, which it failed...

 

Any idea what that test procedure entails? My googling leads to surprisingly few specifics about what it has to fail to qualify for a reman. Maybe a call to Mazda is in order.

 

have had this convo before, if it fails compression that is all you need for a replacement... call Mazda NA if you have to


Posted From RX8Club.com Android App

 

Much thanks, will call tomorrow.

 

there is some leeway, but basically they check compression, if it passes you're done.

if it fails, you replace plugs and coils, unless they are new, and do the zoom zoom engine cleaning, and retest.

if it still fails, you replace engine.

 

OK, I have a case open with Mazda as of this morning, we'll see how this goes.

 

Rotor 2 is a fail, they will replace it.

If numbers were passing but weak they will recommend a Zoom De-Carb, new coils & plugs

 

I think 680 is minimum spec, so it appears they both failed.

 

what is a zoom zoom engine cleaning?

 

Seafoam essentially, I think. Decarb the combustion chambers.

 

^ oh, so I assume that's extra cost to do the zoom zoom engine cleaning? Or is it included in the compression test fee?

 

Extra. From what I understand, if you incur costs to find out if the engine is failed (ignition replacement or decarb) and the engine still fails, they will credit those costs. If it passes as a result, you pay.

 

well this isnt real reassuring, i just bought an 06 shinka with 28k miles in november and it was located in chicago i never asked for the compression test numbers, guess i no exactly what im doing the minute i get it out of storage.

 

Yeah, I figured it couldn't possibly be on the way out without really presenting any issues during an extended test drive, guess I was wrong. Spoke with them today since I hadn't heard back and they are checking with "regional" about the replacement since there are no "issues" other than a rough idle. 50% compression is an "issue" . . .

 

Have you compared your car side-by-side in a pull to see if you are experiencing any "loss of power"?
I know a friend of mine tried that against my 8 and the result was significant...I know my compression is "good" but nowhere near perfect.
Even driving his car, it all feels good and accelerates smoothly etc...but power loss was definitely there... rough idle too*
Good luck with the new engine...although it should be covered!

 

Damn right it should. Did the math yesterday and it would appear I'm actually rocking about 145hp if the compression test numbers are to be believed. :-/

 

Damn 145hp would be no fun...not even sure how you "did the math" to get that...but I believe you
Let us know what happens with Mazda / the engine!

 

Looks like I'll have to get my hands dirty. Just got a message stating they won't warranty it for failing compression alone. Unacceptable.

 

Note: 588 is failing, 589 is still passing, so rotor #1 passes.



The first set of numbers look quite high compared to the normalized numbers. What was the test RPM for those? You must have a crazy good starter.