Compression Loss/Need New Engine?
 

UPDATED ON MARCH 6TH, 2012

My 8 has started acting up again. Here are some problems that I have been having:

• When apply the brakes, the car feels like it is going to stall out every now and then. Stalled once, but hasn't done it since.
• Idle is very erratic. Sometimes is idles very smoothly with no problems and sometimes it is right at 500 RPMs and feels very shaky.
• This I am not so sure is a problem, maybe the engine is built this way, idk. But, if you try to go fast off the line, it feels very weak. It won't go as fast as I feel like it should be. It still accelerates decent, but the initial response sucks.
• I don't think this is related, but it is a problem I have been having. It's getting hotter out and I want to turn the A/C on, but if I leave it running and come to a stop, my idles get REALLY BAD and it stalled on me twice when I first got it so I can only have it on while I am driving, which is very annoying.

Now I had the problems before, but haven't experienced them regularly. Now it has happened twice in the past week, which is starting to worry me again. I have been trying to do some research on these problems which has lead me to thinking compression loss:

https://www.rx8club.com/showthread.p...alling+braking

My 8 is an '04 Automatic with roughly 34,000 miles on it. Had the spark plugs and coils replaced around 32,000 (although I do feel that they didn't replace them ALL), and have regular oil changes every 2,500-3,000 miles.

bumppp

I would take it to a Mazda dealer for a compression test.

Clean your mass air-flow sensor.

I have already done that a few weeks ago when I helped my friend with his too.

What numbers should I be looking for to tell me if my compression is bad?

This is the exact same thing my 2004 AT is doing right now. Yesterday it stalled and now it idles exactly how you describe (with the AC and everything). Let me know if you find anything out.

This is from the 2009 Workshop manual; it will help you interpret compression results:
https://www.rx8club.com/showpost.php...&postcount=123

hi, my rx-8 wouldnt start at all for me the other day i got it towed to the mazda garage and they did a compression test on it and said the compression was low on the front & rear rotors, but they've told me theres nothing they can do it for it and that my engine needs to be replaced!! just wondering have any of ye had this problem and were ye able to fix it without replacing the engine ?

if you have low compression due to wear/damage, then your only option is to replace. but you may want to try giving it a good seafoam/atf soaking and cleaning as you may have some loss due to sticky/stuck seals/springs

I just had the dealership do a zoom-zoom cleaner on my car on my last service (around 2,000 miles ago), is that the same thing?

I had the engine shaking also. Dealer said my engine mounts were cracked & needed replacing. Got a second opinion....no cracks. They cleaned my throttle plate & guess what? No more shaking. Running smoothly again!

^...............yes....a lot of times this idle issue will first appear on a manual car as you are going to neutral and rolling up to a light or something. The idle starts to fall off, become somewhat erratic, dips to low, stumbles, then almost cuts out or will cut out. First time it happens you will think it's just one of those things, then it will start happening more and more and won't matter if it's cold or hot.
Cleaning the throttle body(buy some cleaner and use a rag) should be done at tuneup time when one does plugs, air filter, oil change. Clean the MAF, and check the accordion tube at the same time as well.


I monitor my ECU voltage real time(as well as digital readout of rpm's), and believe it or not, you can sort of tell beforehand that it's going to happen because instead of the normal 14.2 volts, I will start to see 13.8 volts at idle(as rpm's slowly start to fall off as I throw it in neutral), but as soon as you put it in gear and hit the pedal it's right back up to 14.2v.....no big deal at this time right........then it will start to get worse(13.2v) as my idle slowly but surely continues to fall off over the next week. Then the real stumbling and stalling begins. At this point I know it just not high enough idle RPM's for the alternator to put out the right voltage(now it will be 12.2v or even below) while in neutral.

So now when I notice it starts to get to 13.8v or 13.6v when I'm idling in this manner, I clean the throttle body and bingo.....right back up to 14.2v

Sometimes the slow change in idle isn't as noticeable as that voltage........so that's when I jump on it.......just my observation. I've only really had to clean the throttle body twice in 6 years, but I just went through it a couple of weeks ago. Cleaned everything but that and was a no go until I cleaned it. Guess the butterfly valve was sticking(not closing fully) and the A/F ratio was messed up????????

Just an update on my starting problem for everyone...

I finally got fed up with it and between discussions with my family members, we decided it was finally time to take it into the dealership and find out what exactly is wrong and get it fixed. I was fed up with these problems lol.

The dealership told me the following things that they saw were wrong that was causing me problems:

.: Coils needed to be changed (all 4)
.: Spark Plugs needed to be changed
.: Battery terminal should be cleaned off and protected
.: My air filter was dirty and needed to be cleaned
.: I needed a new O2 sensor anyway, and they said that it MAY BE A POSSIBILITY that it could be linked with my hot start issues
.: A de-carb was needed on my car

I also got an oil change while I was there. The dealership was kind enough to let me have a rental car on there expense over the weekend and yesterday so they could have the same guy work on my car (apparently had the flu and called out the previous work day). However, altogether, this is going to cost me approx. $1,500.00 for everything. I feel like I have been royally raped, granted I did get A LOT of stuff done to my car (a few more minor things not listed), but I want everyone else's take on this.

you did get raped. you can do all of those things for alot cheaper

1500 is more than you need to RR engine in this car..I'll leave it at that

owch!!!!

UPDATE!

They just called me, and told me that they spoke to Mazda, and they were told to do a compression and fuel pressure test. My 8 passed the fuel test, but my engine failed the compression test. So I will be getting a new engine from Mazda within the week. They also bumped down what I originally paid (approx. $1500.00) down to about half of that which is a plus. Definitely feel A LOT better about all of this!

Whoa, i was about to say 1500?

700 bux sounds more reasonable, although u can buy those stuff for ...

4 mazda boxed oe coil cost less than 200, no mazda box cost less than 100
4 mazda boxed oe spark plug cost less than 130, no mazda box less than 70
Mazda oe wires 70? No mazda box 27
Front o2 sensor mazda box cost 250 i think, no mazda box 150

U do the math

U do the math.

Funny that the very first reply to this thread from nearly 2 years ago was what was the ultimate solution.

BC.

Lol I know I have thought the same thing for the longest time. But they informed me that Mazda would have made them do half of the repairs I originally got done anyway, which is why they dropped the price in half (I think Mazda is actually paying for the other half of the repairs that was done :naughty:).

Overall, this has been a long, painful time coming, but I am happy with the outcome. I hope this solves the problem and I can FINALLY enjoy my 8 the way I am supposed to until I can get rid of it lol.

05, rx-8, stock, padle auto, 45,000 miles ? hot start problems, got new coils wires, plugs, & filters, oh & new batt.done a compression test. on the face i got about 35 psi, bumps, overall rotor 1& 2 are at about 85 psi. dealer set up an appt. for me monday. ive checked it twice & got about the same thing. the dealer said more than likely ill need a nother core. but he could not tell me if it would be a new one or re mannf. any one know about the core ? thanks !

re mannf

Yeah the dealer never specified to me either whether I would be getting a new Core or a re-manufactured Core, but from what I have read I am guessing re-manufactured as well.

UPDATE!!

I just received my car back from the dealership. My 8 starts better than ever! Still making sure everything is good, but so far it feels great.