hey guys, this is my second post on this forum and want to say so far all you guys are the best!
here is my situation im in...
let me start off by giving you some info on my 8.
its an 04 6speed with almost 119K miles.
I had my plugs, coils, and wires replaced. Had a new high powered starter installed, replaced my fuel pump, replaced the throttle body with a used one and of course an oil change with 5-20.

so onto my issue...

the car starts up great when the engine is cold. it drives great, barely any hesitation in idle, but SOMETIMES it will stall when I have it in gear at a light and not revving the gas.

when I turn my 8 off, sometimes right away it turns on when i crank it but sometimes it doesnt. it takes me 4-6 times of cranking for it to turn on. I dont think theres a vacuum leak, and if there is, I sure as hell cant find it.
the compression is good. everything is good.

sometimes i get my check engine light saying my cat is below threshold, but i erase the code every time. it comes back on every 50 miles or so...

any ideas? thanks in advance guys

 

Your list and symptoms sound completely correct if you delete the "compression is good" line. How do you know it's good? Got test numbers for it?


The CEL is for a lack of a cat, you didn't mention if you have a midpipe or not. If you have the stock one on there, it's effectively gutted (or actually gutted if that was intentional).

 

how do you know the comp is good? do you have the #s

man riwwp you alwasy beat me to the punch.

 

to be honest I don't know the numbers for the compression test. Its just what a mechanic told me after looking at it

I was told that the cat has been worked on before, you can tell if you look at it.

I believe its stock cat...sorry for the lack of info, i just recently got this rx8

I should also add that my battery voltage is low...when the car is off, its reading at 12.2-12.3 when normally the minimum is 12.5

This is also probably really random and doesn't have anything to do with this issue, but would Seafoam help? What is it exactly? And how do I use it?

Sorry for all the newb questions. I just converted from BMW to Mazda

 

Read this for the compression test info: https://www.rx8club.com/new-member-f...4/#post4533733 (link jumps to it)

It should be pretty clear from that why your mechanic's information about your compression isn't reliable.

One of the hallmark symptoms of low compression is having trouble starting when hot, and is really the only quick test you can do for compression guessing.




Seafoaming is for decarbing the engine. However, the traditional seafoaming that has been discussed for years around here isn't really doing much. Read this thread, where I tested methods of decarbing, borescoping my engine before and after each treatment to see what is actually happening: https://www.rx8club.com/tech-garage-...r-pics-241867/

Seafoming can be useful if used the right way, but distilled water is just as useful when used in that same way, and 80 times cheaper per oz.

 

Very useful information man. Thank you for that. I'm new to rotary engines I can see why they are a pain in the ***.

 

Sansred They are only pain if you don't educate yourself on them asap. Neglect them and they will bite you back.. Just read through those links RIWWP mentioned and come back to this comunity for any questions and porlbmes you face. People here are far more knowledgeable then most mechanics you'll come across when it comes to your RX-8..
All the best