Synthetic oil causing misfire?
 

I apologize if this has been covered in other threads. I did my part searching and did not find a similar topic.

My RX8 has misfire problems. In January it showed the symptom for the first time and I had it toed to the dealer, as they recommended. They said they could not find a problem but to 'bring it back if it happens again.' The dealer refused to run any tests on the health of the engine.

The problem did reoccur a couple weeks later, and I replaced the coils myself. That seemed to cure it.

Yesterday it came back. I ran through a large puddle (wide, not deep; no water reached the intake) and the car immediately started misfiring. I had it towed home, then to the dealer.

This time they say it's running fine again, but that it does this because I'm using synthetic oil. They also claimed that I may have done serious damage to the engine by doing so. I asked, if that was the case, if they'd do a compression test (since the service writer used the words 'low compression') to check the health of the engine. They refused to do so.

They also claimed that the car was not storing any fault codes. I read a single code off the car yesterday, for a 'cylinder #2 misfire,' and did not erase it.

I'm pretty frustrated at this point. Whether or not you're a proponent of synthetic in rotaries, I fail to see how the oil is the cause of my misfiring problem.

Thanks.

screw them, take it to another dealership....misfires arent cause by the type of oil you use, its either your plugs or coils going bad...

What they are suggesting is physically impossible unless you are injecting oil as your primary fuel.

Don't worry misfires are common.

you won't get rid of them. Car is pig rich from factory.

Re-set ECU

If it continues to misfire after two re-sets then you need to investigate the problem or driving habits.

I second Dozer's recommendation to try another dealer.

On the puddle thing...check the plug wires to make sure they're on firmly, have dielectric grease to keep water out, and are now dry.

Ken

With water being involved right as you through your misfire...Im with ken-x8. I might even go as far as replacing the wires depending on mileage.

Agreed. Wires should be done at the same time as coils/plugs. It's cheap insurance.

I also second finding a new dealer.

I'm curious to know how they are sure the OP is using synthetic oil. I'd be surprised by a dealership that would refuse to do a compression test, but would do a forensic analysis on oil to determine if it was dyno or synthetic. That's the sort of info I wouldn't volunteer to them.

Sorry I didn't get around to writing an update last night. After I picked up the car we were really busy.

I have the car and it's running fine. Basically the dealer doesn't know why the car does this. The service manager called me and agreed that the synthetic oil theory is ridiculous, and finally admitted that they have no idea what's happening. They're going to try to escalate the issue through Mazda, but he wasn't convinced they'd find a solution without the failure being permanent.

When I asked the service adviser why he refused to do a compression test, he said that he misunderstood me and thought I was asking if he'd recommend one. I think it's basically the same thing, and that if he thought I had done 'serious damage' to the engine a compression test is the way to test that theory. If he doesn't think his theory will stand up to that scrutiny, why present it?

Really, the car's running great. I took it for a short drive after leaving the dealer and it's totally back to normal.

I have another set of plug wires. I'll install them once it's dry and warm outside. Right now it sucks outside.

While I wouldn't eliminate the wires as a suspect just yet, when the misfire happened I was able to disconnect all the wires and reattach them. None were wet. One wasn't on real snug, and I crimped the connector a little to tighten it up.

As I said, I have a new set of wires. I'll install them this week, but I expect no change in the car's current behavior.

I would never EVER tell a dealership you are running synthetic oil. What they don't know won't hurt you. They can not test it anyways and have no idea what you are using. Why some are scared of an analysis I have no idea as you can send it into Blackstone labs for an oil analysis and even they can't tell you if it's synthetic or conventional. They can only tell you what's in it not how it's made. Don't be afraid of using synthetic. Just don't tell anyone. No one can really complain it's dishonest as it isn't going to cause anything to fail anyways. It's more dishonest to deny a claim based on the fact that it's there. Therefore ignorance is bliss.

And I was ignorant about telling the dealership. :) After I dropped the car off they called and asked if I was using synthetic. In the interest of an honest exchange between us in order to determine the cause of the problem, I told them the truth. I had no reason to suspect they'd settle on any random, inconsequential factor as the cause.

They no longer suspect it's the cause of the misfire. Their manager has set them straight on that. They just don't know what the actual cause is.

Start your car with the hood up...let it idle for a bit and be normal. Then take a spray bottle and spray water on your wires and see what happens. Do it at night and you might even see them spark if they are bad.

:bsmeter::bsflag::wtf:

uggh. misfire happens. it just does. one time it will be because of a coil issue , next it will be a plug issue and another time if will be a wire issue and sometimes it will just do it for the hell of it.

i have no idea why you had it towed. misfire is never a reason to have the car towed.

as for why they didn't see the code. misfire codes are only stored for a certain amount of time. if no other misfire is sensed then it erases the code. if it detects enough in that time frame then it will light a solid cel. your car didn't detect any more so it erased the code and they didn't see it.

I had the car towed because the dealer has told me that I shouldn't drive the car when the misfire happens. I also assumed that they wanted to see the state in which car misfired so they could figure out why. Apparently they did not. All they did was clear the code, start the car and drive it, which is what they told me not to do.

When I said they didn't see the code, that was a result of poor communication on their part. The dealer later explained to me that they had read the code that was stored when the car arrived, but erased it and then no more codes cropped back up.

Yes, it was storing a code. I read it myself. I understand that an isolated fault won't store a code.

Anyway, you're not the first in this thread to say, 'misfire happens.' How serious of a misfire would you excuse as a quaint rotary quirk? Because this was consistent, no power, giant cloud of smoke misfire. Does that 'just happen?' Is that something I should just accept as part of life with a rotary?

Or are you referring to the misfire that results from dirty plugs or sketchy coils, where the engine doesn't quite rev smoothly?

plug and unplug your maf sensor. look at the wiring.

the big other idea, and i had this happen just recently.. and you mentioned a puddle..

reset your eshaft sensor. brake dance!

i kept getting an odd missfire on cruise. then it would throw a hard 300 code.

reset the eshaft sensor all is well.. :)

beers :beer:

ok see you didn't say that earlier. did this big cloud of smoke happen in January , yesterday or both?

wow, did not see that either..


beers :beer:

I have seen some smoke before, but not like that. Of course, I was under full throttle when it happened this time because I was in the middle of an autocross run.

In January, after the dealer had already given the car back to me once without doing anything, it happened again a couple weeks later. The car misfired all the way home (which is only a mile) and a friend was following me. He said that big, burning chunks of catalytic converter were coming out of the exhaust. When I say it was misfiring, I mean probably only one rotor was working. The car had almost no power and was difficult to get moving. It had done this a few times before when I first started the car and went away as it warmed up. Replacing the coils fixed it at the time. Now it's back, and at random, not just when cold. The car had been running in the grid for probably fifteen minutes before that run, and it was probably in the low 60s outside.

A friend, who was at the event, now tells me that the smoke started to trickle out of the exhaust before I hit the puddle. So I'm not sure I really suspect water any more. There was a long, fast slalom right before the misfire happened, and when the smoke started, so it's possible that violent left-right-left-right caused the symptoms. My car is much stiffer and has much wider tires than stock, so it's probably capable of higher lateral Gs. Whatever part is the problem on my car may be upset by that.

My mistake. That's why I wanted to clarify. 'Misfire' meant something different to you and me.

If you are blowing chunks of the cat out of your exhaust then of course it's going to misfire. Your exhaust is clogged and air can't get out. A cat issue can be a frustrating thing to diagnose sometimes. You don't always get a CEL from it. It may not even always cause the car to run bad. Sometimes the problem can be worst if the engine is warm but not cold. A cat issue isn't always obvious and if the MAzda techs are only looking for CEL's which is pretty common anymore, they may not find it.

Yes, prolly the synthetic.

S

So you think the cat issue predates the infrequent misfiring? Because the misfire seemed to cause the cat problem. Also, 99% of days my car seems to run fine. This is like a switch gets thrown and suddenly one rotor stops firing.

A cat can start to show issues long before it completely fails. They may be subtle things like a perceived misfire every once in a while. As it gets worse, the engine may just not want to run at all. Your cat could have had issues for months before it finally died. Now I'm not saying for sure that your cat is the cause of all of your issues, but it is a very possible one. Brillo had a similar issue a couple of years ago. He had random misfire and replacing the cat fixed it. It didn't even rattle when you shook it after it was off the car. You just never know with those things.

Now that's very interesting. I think I'll call the service manager and ask if they might replace my cat, just to try it.