Questions about engine problems. HELP!
 

Hello my 05 rx8 currently has 50k miles and is under warranty for another couple months. Once my 8 sits and is hot as it idles, it drops rpms and shakes for a couple seconds about every 10-15 seconds continuously (Having a strong idle at 850 and dropping to a shaking at 750). Is this a clear sign that i need a new engine. Also i seem to be guzzling gas at 18mpg avg and I'm doing mostly if not all highway between 3-5k rpm. I was also told by a mazda tech that if my engine were to flood i would be covered for a new one.. Is this true or just a way to fuck me by paying hidden charges. Bottom line is my rx8 is at 50k original and stock and i know these rotary engines aren't the toughest and i believe mine is going to go very soon but if it goes outside the warranty im fucked paying $3,000-$5,000 and i simply can not do that! Any suggestions on your guys part? Maybe flooding the engine or anyways to tell it needs a new engine by simple tests or a way to make it need one quicker? Thanks guys !

check your engine mounts, could be broken or fractured resulting in vibrations.

my 8 has the same exact problem and my engine's compression is fine. Theres a couple things you can do to minimize it.

Stiffer motor mounts, grounding kit, coils, BHR midpipe. These 5 things together helped minimize it for me. When I put in rx8 performance mounts, I could no longer feel that vibration however I could still see the RPM drop. I swapped them out though because of the acceleration vibration some people will tell you about, wasnt my thing.

Maybe look into BHR motor mounts and get a cheap grounding kit?

You can also try and clean up your factory ground as well underneath the stock airbox.

Goodluck and PM me if you have any questions on those things. I feel your pain... trust me.

Motor mounts, clutch safety switch, or neutral position switch tend to cause fluctuating idle issues, also.

BC.

If your still under the warranty, then i think its better to get a compression test done on the engine, just to make sure its still doing good. The compression test is around $150, if it passes, then you will have to pay for it, but if it fails, then the dealership will pay and you might get a reman engine (if everything goes thru)...good luck!

I greatly appreciate all the feedback! Loving the rx8 community so far, but like i said my rx8 is at 50k and after doing weeks of research i find most peoples engines go at around 60,000 and up ... Wouldn't i be best off "killing my 8" in a sense to grab that new motor while i can before it's too late? Or would i be best taking care of her like she's my left nut as i am now, and just investing in full maintenance. It would be the absolute worst thing to let me see her go due to a bad engine in the near future because i wouldn't be able to afford it, I bought her this winter... (ya i know "winter" what an idiot but the guy wanted it out of his garage and i offered 9,500 after negotiations & surely he took it)

You should get a proper compression test at a dealer like Monchie suggested. That is the only way you are going to know how healthy your motor is. Lots of motors have died at way less than 50k miles. The remans can be hit or miss, you might get a bad one that ends up being worse than what you have now.

Hopefully you read https://www.rx8club.com/rx-8-discuss...t-here-202454/ before buying the car, if not you should read it now.

Alright thanks! Would you suggest i run it until i'm 3 weeks or so away from my end warranty date so i don't end up paying $250 twice? It's up on June 1st btw, and as far as gas goes if i do my 30k maintenance (am i best buying the whole kit off rx8shop for 400?) will it slightly improve or not really.. last time it was done was at 20k by previous owner.

I'm not certain I understand you. If you suspect low compression (biggest sign is harder hot starts than cold starts), then take it for a compression test. There is no reason to "pay $250 twice." Most compression test costs are more like $130-$180, and if you fail the test and are covered under warranty then the test should be free.

If you have low compression now, waiting a few months will not serve any purpose unless the timing is really bad now and would be better later. If you DON'T have low compression now, it won't suddenly fail within the next couple months.

Ok that cleared a few things up! And i live in north jersey, every mazda dealer wants $250 w/ tax for the test because their fucking excuse is they need a tech on the car for atleast 2 hours..

250...holly macaroni!

I would recommend asking NYCGPS if he would be willing to test your compression one weekend. He owns an official Mazda compression tester, and is a bit nicer in person than his online persona leads you to believe.

BC.

I'm the biggest (ok, one of the biggest) a-hole known to man kind ! MuHahahaha ! :rollingla

Well, I am out of the country ... and I won't be back to NYC until Sept so ... :(

ahh fuck :tear: well looks like i have no other choice than to drop 250 and hope for good results, thank you anyway though nycgps