jayrerickson

Hello everyone,

I just got a 2004 6spd RX-8, has 146k. The engine was replaced at 86k by the vin from the dealer.

So here is the story how I got it.
I had a 2000 jaguar s-type 3.0 and put it up for trade on CL. This car had problems I didnt want to deal with anymore. 2 windows didn't work. sunroof didn't work. Exhuast had 3 leaks. CATs were gutted. Calipers weren't working right. Bla Bla Bla

So I found this guy 2 1/2 hours away willing to trade for a rx8. He said he was fed up with his car trying to figure out the problems. He only had the car for 2 weeks and never truly looked into the problems.

So I took a chance and went down to him to check it out.

The rx8 would start cold but would die once warmed up. As he just showed the car, it was warm and wouldn't start.

We push started it and it ran perfect. Everything sounded good, shift perfect, drove perfect. Would just die at idle and wouldn't start till cold. Plus there is no CEL.

Had a beer with him and decided to trade him. Drove 2 1/2 hours back with no problems other then giving it gas when stopped to keep it running.

This morning it started up and idled fine. As normal the rpms where higher with a cold start. Once it warmed up it just died.

Now the car is in my garage and I tore it apart. I am very mechanically inclined and have built performance motors in the past, never a rotary though.

So the question is where do I start. So far I can see the plugs and wires were replaced with NGK. The coils do look newer. Drained the oil and on the dip stick there was white sludge like it had a coolant seal failure. Inspecting it farther, The white sludge seemed to be from not letting the car get hot. Letting condensation build up. Oil that drained out was dirty but clean from water.

Then I took the upper IM off with the air intake. Battery and tray is out alone with any vacum lines in the way. I did see oil in the IM.

Is oil in the IM from a bad PVC or is this how oil gets in the combustion camber to lube the apex seals?

What other senors should I clean/check before reinstall?

How can I check the cat with out taking it out? Looks like a new O2 is on it.

Can I try to use a compression tester that is for a piston motor? As use it to see if each plug hole has the same compression across the board? See if one rotor has more then the other?

Can someone kindly show me diagrams for the vacum lines and sensors?
What senor is what and the job it is suppose to do. If the sensors are just like a piston motor then I will have no problem understanding its job.

I did search and getting tired of reading all sorts of solutions, from changing parts to having a fried motor.

Come on people, having a motor run perfect and has all its power but dies at idle is not a bad motor. Horrible information to give and crush peoples dreams just to have a post or 2 out there. I see this all over the forums

Thanks for the help in advance.

Good help is hard to find these days, hopefully I will get it here.

Justin

rickeo

iTrader: (1)

Lot of questions, and I've had a bit to drink (I don't work tomorrow, don't judge me!) so just make sure to read this in its entirety, a few times: https://www.rx8club.com/rx-8-discuss...t-here-202454/

jayrerickson

Thanks, this was helpful to understand what to look out for and what I have.

This still left most of my questions unanswered. Really, now I have more questions lol

These are my thoughts on the situation.

In my case, the car starts cold but dies when warm/hot and wont start when warm/hot.

For a weak coil, wire or plug. In my experience, neutral temps (50 today) the ignition will have a stronger spark. As temps rise, the ignitions seems to get weaker. But I don't see how this would make the engine to just shut off and not start again. I would think it would start to idle poopy and then die. Plus the ignition system seems to have been replaced.

For the apex seals. I could understand that it would start as the oil is thicker and helping seal on combustion, raising compression. At the same time I would think the seals would expand more as temps would rise. Still dont think it would make the engine to just stop.

Possibly see the cat being clogged. When cold there is just enough flow to let the engine run and as soon as it gets hot enough the CAT expands, clogging air flow all together. Stopping the engine dead in its tracks

Could be a sensor with the throttle body. Dumping more air and fuel when cold raising the rpm and keeping it running. Then once it hits that certon temperature shutting off/changing signals it just dies as the engine doesn't have that assist to keep it running.

The weird thing is I don't have a CEL. I do have a scanner that will read live data from the ecu but dont know what normals signals should be at. The scanner will give me data for basically every senor. MAF, air temps, O2 A/F, fuel psi, timing, ext... Can someone point me in the right directions for a data sheet on what the sensors should be at? I

I have been reading the the ecu will adjust to crazy levels until the sensor is died completely. Then throwing a code for it. If this is the case, I will clean everything up and put the car back together. I need base numbers to go off of to see what a crazy level would be.

If it was a piston engine I could figure it out. This one, I have no idea if its the same or what. Sucks I don't have a manual.

These are my thoughts on the situation.

Mr.Mango

iTrader: (2)

I would recommend replacing coils, plugs & wires... they may look new but this is a RX8 and is one of the main causes of driveability issues.

During cold weather, moisture contained in blow-by gases is cooled by the intermediate housing wall and condenses due to difference in temperature. The moisture reacts with the engine oil and the milky substance appears. The substance eventually dissipates when engine reaches full operating temperature.


Check Mazda TSB: 01-07-12



RX8 does not have a PCV, This could be caused by a bad cat (excessive back pressure) OR filling oil too quickly/without a long neck funnel. You will see a hose that runs from the oil filler neck directly to the intake hose.

If you do not have a Cat related code, your only true way to tell is removal.

Standard compression tests are not accurate with the Rotary as it depends highly on RPM

Please see attached for vacuum diagram.

---------------------


For your second post...

Do a compression test, with a rotary tester... if it fails check CAT & do a decarb then retest

IAC is located in your TB

skc

Sounds like low compression if you are having hot start issues.

Get a compression test done asap

jayrerickson

Thank you Mr.Mango for the tips and diagram.

I have the top of the engine apart. Is there any way to get a compression tester for this car. I have been reading they are very hard to come by. Probably a big system with software lol. Never looked into it yet. I don't want to put it all together pay a stealer to do it and then come back to tare it apart again. Would be 10x easier to do it myself.

Mr.Mango

iTrader: (2)

https://www.rx8club.com/group-buy-ce...up-buy-172238/


Mazda Spec:
Standard: 120PSI @ 250RPM
Minimum: 98.6PSI @ 250RPM
Standard Difference in Chambers: 21.8PSI (very high)
Standard Difference in Rotors: 14.5PSI (again very high)

eludinu

I'm having the same problem. Just purchased the car at auction. Ran fine that night. Hot start issues just as yours. It won't stay running now. The previous owner had it over filled on oil so it sucked into the intake. Here's what I've done and it hasn't helped. Plugs, coils, eshaft sensor remove and clean, change oil and air filter, seafoam (decarb) , new battery, checked the starter to verify it was the upgraded one, 20 pedal stomp eshaft reset. Still wont idle. Starts fine at cold but once warm it dies. Runs great till around 7-8k then a cel flashes(misfire) I have to shift to neutral and keep it running at stop lights. Needless to say I'm not driving it lol. I'd call Mazda and take it in for a compression check. That's my next step. Would your motor still be under warranty? If it was replaced at 80k does the warranty start again on that engine? If so I think the compression test is free if you have low compression. Don't quote me on that. Maybe if you figure yours out ill have a better idea of wtf is wrong with mine lol. Oh and for plugs,coils and air filter I got them off ebay. They sell a tune up kit for like 250$. Plugs,wires,coils. Good luck and if I get mine figured out ill let you know.

9krpmrx8

iTrader: (46)

FYI, the twisted rotors option is not available, that guy is MIA.

OP, you need to properly diagnose your vehicle. Try following the troubleshooting section in the Factory Service Manual. If you are not up to the task then you need to take to someone who is.

M A Z D A

jayrerickson

Awesome, just what I needed.

LBirch_5

ok guys im having a little different problem. mine starts fine but always idles from 1-2k rpms, very irratically. sometimes it will just shut off once rpms drop. also i checked the vacum lines. on the left side front, i have a vacum line running to a sensor (not sure which) on the flip side, my buddy has an rx8 but he has a nipple covering it instead of a vacum line running to the sensor. i tried putting a nipple on mine but car would immediatly shut off if i didnt keep rpms up. i have put the vacum line back on as of now... any suggestions fellas?

9krpmrx8

iTrader: (46)

Yeas, my suggestion is to search. Try looking a vacuum diagram in the factory service manual I linked above.

jayrerickson

Search is your best friend. What I have been doing is going through the DIY section and going down the line and checking and cleaning. Just got done taking out the ssv (great guide for it).

Next is taking out the air pump and gutting the cat, just to make sure it is not a contributing factor to my problem. To my knowledge, you don't need the air pump if you don't have the cat.

LBirch_5

thanks bud, once on the link where to go to find the diagram?

jayrerickson

Few more up and you would of seen this https://www.rx8club.com/attachments/...hu0113w002-gif

9krpmrx8

iTrader: (46)

Go to engine, then symptom troubleshooting. Or just Google image search "rx8 vacuum diagram".

http://foxed.ca/rx7manual/2003mazdar..._S01_0016.html

LBirch_5

still cant find wat i need man, its the vacuum line on the bottom left side, which runs up to a sensor that plugs in in the front left of the bay, any clue wat it may be called?

Mr.Mango

iTrader: (2)

^ are you referring to the front left while sitting in the drivers seat or while standing in front of the engine bay?

Front left while in the drivers seat - VFAD (pictured in diagram)
Front left while in front of the car - most likely a coolant line running to overflow? Just guessing here

04Green

iTrader: (1)

For OP and those who jumped on.. If you have a new to you older one, look really hard at the stuff in my $100 thread below. Likely you still need coils, but get everything else cleaned up first so that when you put the coils in you are done, no just masking other problems with new coils.

Traffiking

did you ever find out the problem I'm having very similar issues... thanks

Traffiking

did you ever find out the problem I'm having very similar issues... thanks

NotAPreppie

Last Activity: 09-16-2013 03:13 PM
You aren't getting an answer from him, bub.

Last Activity: 05-04-2014 09:18 PM
Him, either.

If you're having problems like these, you should get a rotary-specific compression test performed and post the results.

New Yorker

Traffiking

thanks for the reply. I'll get the test done asap and post it.