My bad. Gave out the Specs for FC. I was intoxicated on the last post, lol. Standard compression readings = 120psi, minimum = 98psi @ 250rpm

 

Thats what I said yesterday morning... But it was in my head and in bed with a female. Her compression rating was a tad higher than I remembered.

 

Update!!!

So I did another compression test with the vale in and got 118 for the front and 114 for the rear.

Put everything back together with new coils and wires.

It still dies when warm and wont start warm. Through all the cleaning and inspecting, it does the exact same thing as it did before.

I took it out for a test drive and it runs and drives perfect. This was the first time I really got into it for 1st and 2nd. I feel no power lose, no misfiring, no problems.

I have been watching a few videos with RX8s having low compression. Most will still start when warm and runs/drives like crap. Mine runs and drives fine, just dies at idle.

Its not a battery or starter issue. Its starts fine cold and I have a problem keeping it running warm, not a starting problem. When it is running the alt is at 14.? volts. Plenty of juice for the ignition system to run off of.

Ill take a video of starting it cold and warm. See what you guys think of it.

 

Well if it has a problem idling when warm then I suggest looking for a vacuum leak. Even a slight one will cause idling issues. Try following the diagnostic procedure in the factory service manual, it could be a few things.

 

Here is a warm start.

 

I have check over the vacuum lines more then once. I even pluged some of them up to see if there was a pin hole in any of the lines.

I have gone through everything I can. Even replaceing lines with ss lines. Just did a ss line for the clutch (from master to slave) deleted the hard line all together. I have many parts from other projects, I figured why not.

I will spray soupy water around, maybe I have a crack in the IM.

When it cools down I will post a vacuum reading. In fact, I will write down all the readings and maybe someone will find something I didn't see.

This time around the cold start was pretty bad. It normally doesn't start that bad (maybe a little flooded). Still waiting for the video to upload for you guys to see.

 

You should check vacuum when it is hot. Stalling can be caused by many things. Like I said, follow the factory procedures for troubleshooting this issue and you will figure it out.

 

I have gone through a lot of the factory procedures.

Gone through the $100 thread.

Tried every guide in the DIY section. Even polished the SSV. Tested all actuators.

Only thing left is the cat, which really doesn't seem clogged but is a possibility and a true compression test. Everything else I have inspected cleaned and reinstalled.

Maybe it is at that point for low compression. Where the apex seals are there but worn down to the point of not idling.

Question is, will it run and drive with all its power on low compression? As in the upper rpm it creates enough comp to drive normal and not enough at idle?

 

Yes it will run and drive.

 

Here is a cold start of it.


Im going to write down the live data readings and see what I come up with.

 

Why do you not think it is the starter if compression numbers were decent?

 

What are your cranking rpms? Starter sounds weak.

 

put more fuel into tank

get a new starter

 

A starter is not going to make a engine die at idle.

Starting RPM is at 240rpm without the charging support. 250 for the first few cranks.

Would have the data numbers but it died on me. Will try again today.

Fuel light came on while diagnosing. Plenty of fuel left. Had this problem with a 2 1/2 hour trip to get it home. It has seen its fuel cycle.

 

You need to take it in and get a proper compression test at Mazda.

 

but a new starter will get u start when u are warm

u barely get to 250 rpm means it's not good.


it needs 3 cycle, so ur 2 1/2 hr trip will not cut it. but either way, get a test done, I mean a PROPER one that use something like what I HAVE, u know, like a dealership ?

pic was taken when I did a compression test for a FD3S. reference only.




cheap gets you nowhere.

and yes, Even with the compression shown above, the said car still starts and drives.

 

How did you get the starting RPM? You didn't mention that before. I know a starter will not cause it to die at idle but you may also have more than one issue going on.

But, if your cranking RPM's are 250+ then you need to get a proper compression test done.

 

Have you tried disconnecting the cat from the car and starting?

 

the sound from the engine will kill your ears ...

 

Oh come on, you know you love the sound of a no exhaust rotary!

 

non-muffled rotary ... naw I will pass

i think i wanna hear girls scream in bed more ...

 

Yes I agree, I need to get a proper test done.

I agree that a newer module starter is needed, but is not the problem for stalling at idle. I figure I need to figure out the stalling issue before the starter. Rather save money for me to rebuild then to spend money that's not going to fix the main problem first.

I have a live data scanner with blue tooth. Last night I was writing down the readings and then it died on me. This gave me the chance to see what the rpms are with a warm start. Will finish writing the data down today.

I started to take the cat off then a bolt snapped. I left it alone at this point. Now that it is still doing this after new wires and coils, I will take it off and fix the bolts.

If I have to rebuild, I will be getting headers and an exhaust anyway. One thing at a time though, fixing the stalling issue.

 

This is what makes me think its not an compression issue. Those are some pretty low numbers and it still starts and idles?

With the test I done, each face has around the same compression. So I know the apex seals are not blown out.

Just did some research and my numbers might be that low.

With the test I done I got around 65psi on each face at around 240 rpm.

65psi = 448.1592239 kpa. 448 divide by 100 = 4.48

Would 10rpm really make that big of a difference?

Lets say each face has a low number like this. Would it stall at idle from it?

The more I research the more I think its compression. Then you say it will run and drive with numbers like that.

I'm debating on searching for a problem to fix or start tearing it apart for a rebuild. If I need a rebuild, I would like to start now and prepare for it. Of course I couldn't leave it stock. Would have to research for the best combinations of modifications. Best seals, worth raising CR, port and polish, raise oil psi, bigger injectors for future turbo, ext....

I normally don't do rebuilds in the summer, I want to drive the stupid thing lol. Doing it in the winter is 10x better. Seeing snow gets rid of the "I want to drive it now factor". Less misstakes and have more patients.

 

How do you know you are around 240RPM? What are you using to determine cranking RPM?

 

Usually you need two or more faces to stall out at idle... But I've done it with just one reading 6.2 the rest reading 7.1 everyone thinks apex seals are the only thing that matter...

Sigh...