Compression test today......
 

First, my 2007 RX8 seems to run well - no starting issues, and has good power through every gear and at all rpm's. 42,500 miles on the odometer. MPG ranges from 14.5-16.5 and is mostly non-highway driving.

I had a compression test today at a local Mazda Dealer for $90 - front rotors tested at 6.4/6.5/6.4 (failed) and rear at 7.5/7.4/7.5 (ok). The Dealer called Mazda who ordered a Decarb/Seafoam, and retest. No change. The good news is Mazda ordered a replacement engine with no argument or issue, honoring the 8 year warranty which expires in June 2016.

While I've only owned the car for 4 months, this Dealer's Tech has been working on this car since 2008, and he's going to install the engine which is good. No worries there.

Comments/suggestions welcome on what to look for (besides compression numbers around 8.5) with the replacement engine.

Check that fuel line connector, make sure it is secure. Insist on replacement if need be. Don't be one of the car fires that destroys the car.

The compression numbers on the replacement engine will be in the 7s, and will slowly climb as it wears in over the first 5-10k. High 7s is what you should expect by ~10-15k, anything more is a nice bonus.

Thanks for the advice. The dealer mentioned a 12 month/12,000 mile warranty on the replacement. Would my original 8 year/100K warranty supersede that since it doesn't expire for another 23 months?

I had that question of my own 8 a few years back and called MNAO for what their ruling on it was.

They stated that it was up to the district manager over a given dealership whether or not to honor the 12month 12k service warranty on an engine when it is replaced under a different warranty (like the engine core or powertrain warranty).

Considering that your 8yr 100k will expire well after the 12m 12k, then the 12m 12k doesn't really have any impact, and your normal 8yr 100k coverage will continue without interruption. The only time there would be a question is if your 8yr 100k expires before the 12m 12k (like mine did), which is the case of it being up tot he district manager to make the call.

Excellent - thanks!

Yes your original manufacturers warranty 8yrs/160k should supersede. I'm getting my 3rd engine put in my 07 GT next week she's got 158,000kms no questions asked. Can't wait!

Okay, I'm fairly new to the rotary engine and do not know a whole lot about it. I do understand that compression is a big part about them correct me if I'm wrong? My 04 Manuel rx8 runs great until I run it for a long period of time it begins acting up and loosing power till it shuts off from 1st gear to second at 3000 rpms in 2nd it just looses all acceleration until I shift to third as long as I keep it below 3000 it runs okay just very sluggish. I keep it in 6th it does fine it just takes time to get it there as I said I'm new to these engines and cars so any help or suggestions are greatly appreciated thanks !

Clogged catalytic converter, probably from failure to maintain your ignition in good working order, though there are some other possibilities.

Driving with failing ignition will kill a cat failure pretty quick. It will feel like there is a cap on power that gets lower and lower, eventually keeping you from getting to highway speed. Continuing to drive on a clogged cat can and will result in engine damage, O2 sensor damage, and eventually a car fire.

That makes sense thank you. Any advice on how to fix this I know I an missing a O2 censor but can't find the right one and I know my crankshaft censor is missing ? Any help here is greatly appreciated as long as how to maintain my ignition and glogged cat. Thanks

The crankshaft sensor* is mandatory for the engine to run at all. If it even slightly out of position, the engine will never ever fire, because the ECU depends on it's signal to know when to inject the fuel and when to fire the spark. Without it, the ECU will just sit there, waiting for the signal. You have the sensor, though perhaps you mean it's dirty?

If the rear O2 sensor is the one that's missing, that isn't a problem. If it's the front O2 sensor, then it's critical and that easily could be the source of your car failure.

There are lots of other possibilities too, so I can just give you a set of step by step instructions of "how to fix it".




* known as an e-shaft sensor for rotaries, since rotaries don't have a crankshaft, but the e-shaft serves the same purpose

I'll check both censors and find out which it is should I go ahead and clean out the cat along with replacing the o2 censors ? What are the best ways to clean out a cat like a punch rod or something ?

Yes, a metal rod works for gutting the cat. Be sure it's clogged though, it would be a shame to gut a perfectly good $1,300 cat just because some guy on the internet thought that it is probably clogged based on some text-based descriptions :)