As the title states my wifes rx-8 has developed a dead miss from an idle to redline, under load, no load, ALWAYS. The weird thing is it doesnt start doing it till it reaches operating temp. I replaced plugs, wires, and coils. The coils seemed to help a little but it still does it. I am wondering if it could be a fuel injector? The best way to describe it is: if you pulled one plug wire off of a v-8 it would have a dead miss. It will still run and drive but it runs like crap! PLEASE HELP

 

I forgot to say, it is on its second motor this one has about 30k on it. The CAT has been gutted, it has mazda speed exhaust and cold air kit on it.

 

Step 1 - inspect plugs. Does one look damaged, carbon fouled, or fuel fouled?
Step 2 - hook up a timing light to the car, and switch from wire to wire, while slightly reving the engine to see if all 4 coils are firing.
Step 3 - Hook up a compression tester to see if you have a dead rotor face, or a leak into the cooling system.

BC.

 

Can you please describe what you feel is a "dead miss" more completely?

From your description of pulling a V8's plug wire, this isn't really possible in a rotary. Pulling a plug wire will make that rotor run universally worse (to what degree depends on which wire), but won't make any miss or lope feeling to it that could be comparable to pulling a single plug wire on a V8. About the only thing I could think of that could produce that kind of behavior would be a single rotor face that isn't producing power. Perhaps a pair of adjacent faces.

 

It sounds and feels exactly like a v-8 would with a plug wire off. I know it shouldnt be possible in a rotary but that is what it is doing. Could a fuel injector cause this. I havent done a compression test. If I hook a tester up and turn it over would it show me a dead rotor face. I know its not a proper compression test but in theroy I should be able to see each rotor face on its compression "stroke" with a standard compression gauge right?

I dont really know any other way to describe the miss other than it is a mis-fire that is consistant from an idle to redline, and it is down on power. I know what one sounds/runs like when you lose compression on one rotor (been down that road) This is much more suttle than that, kind of like it is down a half a rotor. LOL

 

Well, it's a totally different engine.

Every coil, plug, wire, and injector is doing something 3 times every crankshaft revolution, once for each rotor face. Unlike a V8, where each is doing something every other crankshaft revolution, and JUST for that cylinder. One component not working certainly has an impact, but it has the same impact for every face in that rotor. You can feel that something changed, but it generally shouldn't make it any more uneven.

Note, I've never had a V8 to pull a plug wire from, so I am only assuming that you are referring to a "lope" of some sort, where on that cylinder's power stroke, there isn't any, and you can feel the lack of power production as an unevenness in the revs or power delivery. The only way that this can happen with a rotary is through basically missing apex seals. Something that makes one rotor face get treated differently than the next rotor face.

 

I would assume you have an ignition issue first....reset the ESS..

Then use a coil tester to check the coils/wires again ( see the TeamRX-8 thread on that )..it isn't unheard of to have a dead "new" coil.

Check the plugs...a non firing plug will have an electrode that is fouled..it is easy to see..will look different than the other ones

Are there any codes? If the ignition checks out..then look at the fuel system

 

I just put the plugs, wires and coils on after this started. I pulled the plugs today and they all are perfect in color. I also pulled the wires off one at a time while it was running and they all had the sae effect on the way it ran so I am about 90% sure the ignition system is doing its job.

Where would I even start on the fuel system?

also you said reset the Engine Speed Sensor? how do i do this? yank the battery cable or do you mean physically adjust its gap?

 

another way to describe how it acts, is it acts like the timing is extremely late

 

ESS = E-shaft sensor, or eccentric shaft sensor.

It's basically the equivalent of the crankshaft sensor, and in the same basic position with the same basic function. It sits below and to the side of the main pulley and is used by the ECU to determine where the e-shaft is in it's rotation, so it knows when to fire the ignition and inject the fuel.

If this is fouled, it could be messing with the signal across a 'band' of the rotation.


Your latest explanation does little to help those of us that have never messed with timing

 

Does it idle well?

Fuel system..check FP first..if it is normal try and figure out what load level the missfire is occurring at. If it is all over the map it is more difficult...if it is at the same relative spot every time you can figure out which injector it could be easier

The MAF could be a problem as well...but if there are no codes it is less likely...

You really need something that can read the ECU data to make it easier to diagnose. You might be able to notice something that way that is out of place

 

It still has a "miss" at idle but it will sit and idle. If you free rev it it seems to idle better afterwards. I am going to go somewhere and have the ecu read tomorrow. It has a permanent light because of the CAT but it did flash the other day so mybe it will tell me something. The miss occurs all the time at all rpms from an idle to redline. It NEVER goes away once it starts doing it. Like I said when the engine is cold it runs great., but as it comes up to operating temp it starts acting up and then gets a little worse after about 20 min. of driving but that as bad as it gets (if that makes any sense)

 

Also Thanks soooo much for your replies. I am ready to drive this thing into a tree. It has been a nightmare since a month after we got it.

 

Ok so today I had the ecu read and it just says misfire on #2. I came home and pulled the plugs, all looks well maybe a little lean if anything. It has compression on #2. I put my compression tester in the top plug hole and turned it over. It would bounce to about 60 psi. on each side of the rotor (front was exactly the same). Next I took the MAF out and cleaned it. The wire on the outside of the MAF has some green corrosion on it problem? Then I took the ESS of and cleaned it. It had a ton of metallic crap stuck to it problem? I havent drove it yet to see if I helped it any. Also today when it started acting up real bad I noticed that if I put it in N and revved the H@*L out of it it run run a little better for a few min. IDK please dont give up on mee and help me figure this turd out!!!

 

Ftfy. Alternatively, "1 time every eccentric shaft rotation".

Metal bits on the ESS is normal to an extent; it's essentially a magnet.

Try getting that corrosion safely cleaned up. Probably not too much of a problem.

60 psi sounds rather low (even for possible low-RPM starter? dunno exactly)

Clear the misfire code and see if it comes back again.

Maybe make sure the coil to plug wiring is in the right order?

 

After cleaning the ESS, make sure you do the e-shaft profile reset by turning the key to "ON" (without turning engine on), pump brake repeatedly until you see the temp gauge (or oil gauge, I forget...), sweep fully.


Better yet, check out this thread https://www.rx8club.com/series-i-tech-garage-22/suffering-misfire-start-here-222280/

 

Ok cleared codes, cleaned ess, check plug wire order, and cleaned MAF. NOTHING.
I did determine that the bottom (leading?) plug on #2 seems to be the weak link (pulled the wire while it was running little or no change in engine tone). It is still too hot right now to pull the plug out. Can anyone tell me how the leading/trailing plugs work?

 

Thanks That is what I meant.


Yes, you can pull a plug wire while at idle without making a noticeable impact on the engine.

This might be useful to you: http://www.rotaryengineillustrated.c...nition101.html

Note: I don't think the "waste spark" is used on the RX-8, but I am unsure about that. That website was mainly made for the RX-7s, which are different in quite a few subtle ways.

 

That link helped me understand a little better. I am certain one of the plugs on the rear rotor is not firing for whatever reason. I am starting to wonder if I got a bad new coil. I just dont know what else it could be. Gonna pull the plugs and make sure I didnt crack them or something putting them in.

Ohh and as far as the compression. I pulled the schrader valve out of my compression gauge and stuck it in the trailing hole and just cranked the engine. That is probably why the numbers seem low. I know its not the right way, I just wanted to compre the two rotors and they were the same. It also helped me see that all three sides of the rotor had compression.

 

Grab an ignition tester from the local parts store for ~$15.
http://shop.advanceautoparts.com/web...7CGRP2107_____

Stick the plug wire from a suspected plug on the ignition tester, start up the car. If it is firing normally, you will see a steady spark, steady in color and firing rate. Shut off the car and swap to another plug wire, etc...

If you find one that is clearly "off", swap plug wires on that coil to see if you can rule out the plug wire as well.

 

OK. So I have picked the ignition system apart and everything is working. My next guess would be a failing injector. Any thoughts? When I took the plugs out they where white (Lean) and it is spark knocking under a heavy load. Is there a write up on here for checking fuel pressure? I searched around and came up empty handed. I understand the pressure regulator is in the tank, is this correct? I am pretty sure that it wouldnt be the pump because the "miss" is staying with the #2 rotor so maybe an injector is getting hot and failing?

 

It's possible. The injectors are under the UIM, so they are a bit of a pain to get to. You could always try swapping front and rear injectors and seeing if the behavior changes at all, though I'd only recommend it if you are really as flabbergasted as it seems you are.


You haven't mentioned a location at all. Perhaps any local help on site might provide a different set of eyes on the problem?

 

I am in Southern Indiana, near Louisville KY. We have a dealer BUT..... There just isnt anybody around here that can work on rotaries. Everybody seems amazed that an "engine" can run without valves! LOL IDK

 

Hmm. None of our major members are near there. Here is their thread though: https://www.rx8club.com/mw-rx-8-forum-31/louisville-ky-153751/

Can't hurt to see if there is anyone there willing to get another set of eyes on it.