Signs and symptoms of low compression
 

Ive been worrying lately that my 8 has low compression. i know that one of the signs is hard hot starts which is a problem i do have. compared to when the engine is cold it takes much longer and sometimes barely starts when hot. other than that however there doesnt really seem to be anything wrong. perhaps im just not aware of those so is there anything else i should be looking for?

Hard or slow starting when warm is a sign of weak compression. Based on my experiences so far, the rx8 pcm is quite picky about it's engine's compression in order to run properly as compared to the older platforms that could more easily tolerate a weak compression engine.

Unfortunately by the time the symptoms show up the seal wear has already been ongoing for years and there isn't much you can do at that point except save your pennies and keep running it, hoping for the best. A fat 2 cycle ratio in the gas can help bump compression slightly and prevent further wear so it might be worth a try to see if it makes a difference for you.

Now of course it goes without saying that compression is not the only cause of weak starting. Plugs, wires, coils, fuel injectors, battery, starter, these are all significant contributors to starting that should not be overlooked. Barring a failure of one or more of those areas, weak compression is more often than not the cause of hard hotstarting.

Very good but also how is your idle when hot or cold?

Does the car hold idle well?

RR saved you a lot of searching with this.

I too would like to know the signs of low compression besides hard starting when warm?

Multiple choice:

A) who lives in a pineapple under the sea?

B) SEARCH NOOB

C) difficulty starting, difficulty idling, stalling at idle, slight power loss

D) low compression values when THE ENGINE IS ACTUALLY TESTED FOR COMPRESSION :rolleyes:

E) Both C and D

F) picardfacepalm.jpg
http://www.rotaryresurrection.com/kl...rum/picard.jpg

What a waste of space. If you can not give a good answer there is no reason to be an asshole!

you really need to be careful how you talk about me on the forum, i dont appreciate it. tone down the disrespect, i dont know where you're from but where i am from, we dont tolerate that. dont even reply to this, just keep your mouth shut. consider yourself warned.

The idle is fine, no problems there, regardless of temp.

Plugs, coils, wires were just replaced a few thousand miles ago so the issue isnt there either

Like i said, the only problem ive noticed is the hard starts when the engine is hot. It makes me wince every time i start the car when hot and it takes so long to do so. My poor engine...

Having just gone through a similar issue, I'd advise that you or someone else check out your starter. I too was having issues with hard starts when the engine was still warm and especially so after the cold weather set in. I feared low compression too, but it turns out a dying starter was to blame. A speed test confirmed mine was spinning about 100 rpms slower than spec, which should be around 280 rpms. Bear in mind this was a revision b starter without a lot of age or miles, so they can, and obviously do fail. Now, it's click-whir-done and my problem is gone. My compression test showed great numbers and the tech even commented on how healthy the engine was. Just because you're experiencing a "symptom" of low compression doesn't make it so. There are far too many variables with these cars. Run through your ignition system, eliminate some of these variables, and then start considering low compression if you're still not seeing results.

I suffer from the hot start issue ... however I'm not convinced it's low compression but without a comp test I have nothing to stand on ..... but anyway what I do ....

If after a 2 or 3 seconds of cranking the car doesn't start ... I stop and let the starter disengage.
I then try again .. and typically it starts right up ....

Yeah yeah I know this prolly means one of the rotor faces is suffering low comp .... blah blah .. blah "I can't hear you"
;)

Most members know by now that the search function on this forum is not too efficient.
Most people here also know, or have learned, that being scolded for NOT attempting to search is simply a rite of passage around here and it should not be taken personally.

Mazda issued TSBs for hard hot-starts years ago and those TSBs steered Mazda techs to check/replace the battery and starter before they then examined the coils, spark plugs, and wires. The new starters are WAY better than the old ones but one may wish to have their compression values checked once in a while as part of a regular regimen.

also .....

https://www.rx8club.com/series-i-trouble-shooting-95/hard-starting-suspect-your-starter-motor-check-out-207244/

If the car is idling fine, then I'm assuming its not dying on you at stop signals or so.

There is one issue that popped up recently with a friend's RX8...and it started exactly like your problem... with hot starts. After the hot starting, the car started vibrating, was unable to hold idle and was making pinging noises at high revs. Plugs and coils were fine, so this all sounded like the engine failing. However upon the suggestion of another friend, he changed the fuel and it all went away. The car started running like new again... compression was also tested later and it was fine. He also started premixing after this and says his car is running better than before.

If you've changed your fuel recently, you might want to look into changing back.

When i get a chance i will post up a couple videos highlighting the significant differences between a cold and hot start

he actually did give a good answer mixed in with a little sarcasm and humour . ;)

Evidently, only spoon feeding, hand holding, and other forms of coddling are permitted here now. :rolleyes:

RR is about to beat some ass....

but I understand it statement about searching...it's there for a reason...why do we need 192848490509394 posts about this issue when we can have ONE GOOD/GREAT/INFORMATIVE post

there should be a forced "how to/where to find" tutorial video for anyone joining a forum.

Search is probably so inefficient because we have so many duplicate threads. Also, google with "site:rx8club.com" works pretty good.

That has always been the case.

He did actually answer your question.

is it me, or are some posts missing?

I removed some of the posts and I should probably edit these last two also.

That's a moderator doing his job!

Can we just get back to the fact that this guy might have a bad engine.

OP: If you search, you will find a lot more useful information than the replies that you will get to this thread. Your question has been well answered many times, and I think that there is a sticky thread here someplace. Try the Tech section.

RR - Get over it. It isn't that big of a deal.

And Maniac, I am disappointed that I think I have seen that profile pic. before. It must be time for me to leave this forum if I have hit the top of your profile pics again.

Damnit!

Fixed!

So, let me be sure I have this straight. Apparently, it's not permissible to dispense free and accurate information along with a little humor and (deserved) sarcasm injected, without posts being deleted/edited or people calling for the thread to go back "on topic". Yet, concurrently it seems perfectly acceptable to discuss a member's profile pics in that same thread.

Gotcha. Gotta love a double standard!

POT

KETTLE

BLACK

:rolleyes:

You are an angry, angry man.

Good thing you appreciate the benefits you have derived from such.

Maniac - Thanks! I have not seen that one before.

RR - Normally, I wouldn't but this thread died an ugly death a while ago.

I also never objected to you making a little fun. I just don't want a big flame fest between you two because I am selfish and don't want to read it, and I generally like reading what both you and Maniac write. Have fun!

^I always have my flame suit near by for a flame fest.....just in case i get some second hand flame!!! LMFAO

.....this made me LOL. Gotta love the internet.

People be "e" thuggin LOL.

I understand sarcasm being used from time to time as long as it doesnt cross into the "rude" section. I have found a lot of good information on this site and the people for the most part seem really cool and helpful. I can also tell most people on here are pretty knowledgable and willing to help. I like that.

As far as your engine issues, my 8 has about 105K on it. It takes it about 2 seconds to start when cold but on a warm start it sometimes take about the same as well. I had a leak down and compression test done and all tested good...so dont be too worried or let compression be quick to come to mind because of that one issue, even though I agree with you keeping compression issues as a thought of why it could be doing this. The best way like they said is to have a compression test done. Also another thing to check would be when its cranking to start...does it sound like a strong crank or kinda like its struggling? The reason I ask is it could be your battery as well.

Guess some people are so sensitive they can't take a joke, or have never seen "ethug.txt" in their travels on the internet.

Yeah, my car was cranking slow so the dealer mechanic insisted on installing new battery, although I didn't think it was bad [had it in there for a compression test which it passed at 95K miles]. Anyway, I talked to the mechanic for a couple of minutes after he installed the new battery and insisted that it wasn't the motor either from the symptoms and must be in between. He checked it and found corrosion on the terminal post of the started motor. That WAS the problem, and I think that it is something everyone should check because of where the starter is and how much gunk gets on it.

All of that long winded stuff is just to agree that yes, there are other things that can cause a long start than a bad engine.

Thanks for coming back with with what the problem was .
another thing to add to the list of possible issues .

+1
I'm going to check mine this week.
Thanks Haze

What if the car doesnt have power when putting it into drive? Because thats the problem I'n having. Is that weak compression

No that's normal. It is an automatic Rx8 after all hahahaa.

TNC FTW!

:hahano:
yes sounds normal

In drive you could be at 2k rpms doing fifty.....if you want more power drop it down one or two gears and you are all set....it's good to rev it to redline.... after it's warmed up good of course.:) All the fun in a rotary are in the high RPMS!

I think that you need to express this a little better. Are you saying that when you turn the car on cold, then move the selector to drive, hit the accelerator, nothing happens, as in the car won't move? Will it rev up, does it stall? Does the car move at all when placed into drive?

Hearing your issue the way that I heard it, it sounds less like an engine problem and more like a transmission problem, but it could be a low engine power problem. Need a better explanation of the problem.

I'm thinking of buying an 04 Rx8. The test drive was great... there is some vibration from the rear left tailpipe while idling in drive, is that a sign of low compression?

I don't think is a sign of low compression. Is your engine vibrating when in idle? Check your tailpipe, it might be loose.

A number displayed on a gauge connected to the engine, which is less than the number stated in the service manual, is a sign of low compression.

(Can you figure out what I am trying to tell you?)

No the engine doesn't vibrate any more than an engine does while running, the vibrations aren't coming from the front nor does the engine visibly vibrate. While the car was parked in idle I walked to the back and listened at the tailpipe. Thanks for the input, but the more I go over it in my head the more it seems like the tailpipe was just rattling around in the fender housing.

Search FTW, although I almost feel like a wiki system might be useful for the "one great post" idea. Anyway, ya pays your money, ya takes your chances!

I just got my RX8 and when it's on and running it's great. Power seems to be there, idle is just fine. i hear nothing strange from the engine, but the start up is slow as hell. I'm going to check this starter gunk build up issue tomorrow and see if that is it. it does take about 2 seconds for it to start on a cold. about 3 maybe 4 on warm.

Low Compression
 

I have the same problem for me necessary doesn't take very looong to start like he said but it takes like 3 or 4 seconds to start. My 8 idles perfect just changed plug/wires and coils starter as well. I don't know if this is normal or not?

5 years later and they still can't figure it out. :(