Engine smoke and bucking
 

Hey everyone. Really bad morning for me.

2006 Shinka with 75,008 miles on her…

My drive to work this morning in 12F was going well when suddenly after driving for about 15 minutes I notice that my cabin began to smell like gasoline or a burning smell. There was a large truck next to me so I did not think too much of it at the time and I was at a red light. As soon as the light turned green I put my 8 into first and began to accelerate then when I switched to second gear the car started to rev by itself much higher than it should have and then bucked when I got it into gear, thinking this was also a mistake on my part with the clutch I kept on driving and switched to 3rd and then 4th normally, when suddenly my RPM dipped and the car began to buck as though there was no gas in the engine ( mind you I had half a tank of gas) I went down to 3rd gear trying to give it some revs but she just kept bucking and bucking. When I pulled over to the side of the road I saw LOTS of smoke coming out of my hood and the gas smell was extremely pungent. I popped the hood and let the engine breath and after I removed the engine cover I got a huge blast of 93 octane right to the face. Very wozzy…

Before any of this happened and during the events there was no check engine light, no misfire blinking light, no check oil light, no engine temperature light, nothing was overheating from what my instruments showed, and I checked my oil and coolant levels myself and they were all in order. No leaking from under the car of anything from what I could see.

I attempted to start up the car after letting it sit for about five minutes while I waited for my ride to get there. The ignition and crank were a little longer the it normally takes and when the engine started it went right up to about 4k RPM and then when I dropped the clutch it went back down to about 1k and then began to sputter and drop to ~500RPM and try and come back to ~1000RPM only to keep sputtering so got worried and shut her off… no smoke this time though.

The last thing I did before I left with my ride to work was check the OBD2 reader I had and check for any error codes which I found none =(

If anyone has any ideas on what is going on that would be great.

P.S. The last thing I will add is that I am the second owner of this car and the first owner had his engine replaced by Mazda only 15,000 miles ago under warranty and the engine in my 8 is practically brand new from what I have been told… unless I got a lemon :-O :dunno:

check the fuel line connectors theres a red one and a blue one in the dipstick area

Your story is a bit confusing. The revs increasing without speed increasing and the smoke suggest a clutch failure, basically the clutch disc just burning against the flywheel and not transmitting any power to the transmission. This would produce a bad smell, similar to burnt rubber but with a much heavier sulfur smell to it. I wouldn't describe it as a "gas" smell.


You also say that you got a "blast of 93 octane to the face". Does this mean you have an active fuel leak in the engine bay that is pressurized? Are you sure you were hit in the face with liquid gasoline? The number of things that would have to have gone wrong to produce this is without setting your car on fire is substantial. It IS possible for the fuel line to come loose after it had been recently disconnected (like from an engine replacement), however if it does the car has a damn good chance of bursting into flames and burning to the ground, and you sure wouldn't be able to get it refired again since there wouldn't be fuel getting to the engine. So this whole part confuses me, and makes me think that you are using the wrong words here, and what hit your face was probably smoke or steam, and not raw gas.


Care to clarify?

I would be more than happy to clear things up and I apologize for the confusion. My attitude this morning has been less then professional at work and in general I am a bit sour. I love my 8 and feel powerless and frustrated at the same time =(

The car was going into gear and I even drove it while it was bucking for about a mile to where I parked it. The smell however was a gasoline smell I’m almost sure of it… I apologize for being sarcastic with the “93 octane” comment because it has just been a really bad morning for me. When I took the hood cover off it was not a blast of liquid, but a blast of (what I think were) gas fumes that came at my face.

I am sure that what I smelled was gasoline, then again I am by no means a car expert and could have made a mistake, but to me it felt like it was gasoline fumes that I smelled in the cabin and under the hood

Could the problem be related to the clutch? This is very possible and I do not count this out one bit to be honest. The past month or so it has been hard to get her into 2nd gear and the 1st to 2nd shift will most of the time end with a slight grinding before it goes into gear. 3rd and 4th are no problem and 5th and 6th are perfect. I have long suspected the clutch on my 8 being the problem because it is the original clutch in the car and I have been looking at buying a new one for a while now.

Ok, it does sound like you have two problems here.

1) You do have a clutch related problem developing. It may not be a clutch failure, but it is probably one of this list: Clutch disc, pilot bearing, release bearing, contaminated fluid, master cylinder, or slave cylinder.

2) Your new description suggests that you do have a fuel leak, and since you smell it in the cabin heavily, it is probably a fuel leak at the fuel pump, which is under the rear driver's side seat. Pull up the cushion and remove the access panel to get to it. If you pull this and see wet areas or an obvious leak, this is your problem. It is likely causing a pressure drop, which is creating unstable fuel injection amounts which are under what the ECU is expecting. I recommend against driving the 8 until this is resolved, as it could create a lean spike that could destroy the engine. It generally just requires a replacement fuel pump to fix.

check your clutch pedal bracket first they are know to break.

Thanks a lot guys for the feedback and advice... and sorry once again for the confusion. Just like you guys I am very passionate about this car and I tend to freak out when something goes wrong.

I am going to have the car towed back to my house and take a look at all the symptoms and things listed here. One of my co-workers also believes it could be a simple vacuum leak and nothing to bad. I am going to work my way down a check list of things and check the clutch and any related parts on the clutch to see if that is causing the problem, then work my way to fuel and engine problems.

If anyone else thinks of something please let me know and I will be posting updates as I figure things out after work.

Thanks again for the advice and time :-)

*UPDATE*

I got a ride over to the car after work and discovered a HUGE puddle of gas under the front right wheel of the car... image
Attachment 288244

there is no doubt in my mind now that this is a fuel/gas leak problem. We are currently towing the car to my house to get a better look of things... I am yet to see any wet spots inside the car but the inside completely REEKS of gasoline. more info to come soon

*edit*
upon searching the forms i came across this post related to a fuel pump leak? maybe this is my issue as well?
https://www.rx8club.com/treadepot-15...81/?styleid=17

It is probably the fuel rail connection. You'll have to pull the upper intake manifold.

see my previous post about the fuel line clip by the dip stick. wait you said right side, the driver side or the pass. side?

passenger side

*UPDATE*

Got my 8 home and took a closer look. We noticed that when we turned the key to the accessory position and the fuel pump primes itself, behind the engine on the fuel rail we can see bubbles and some gas shoot out with a hissing sound. going to take off the intake manifold to investigate... ill search the forums for a guide unless someone else already knows of a better location for one.

I would like to thank everyone for the help, support, and advice thus far, it means a lot to me

you should try to locate the leak with a borescope before tearing into it, partly because once you pull off the intake you lose about half the fuel line connections to the engine. one of those lines removed during disassembly could be the problematic connection.

The upper intake manifold comes off and the fuel lines stay in place. You just have to loosen the 2 little clips below the 2 little clips below the throttle body. Heck you only have to loosen one and remove the vacuum line with the manifold.

just to clarify... should I use a borescope? or is taking off the manifold to investigate ok?

The sound and bubbles are defiantly coming from behind the engine near the intake manifold which would believe me to think that my fuel rail has come loose or broke off... any ideas?

My plan is to look into it on Saturday after I get off work... right now nothing has been touched for fear of causing and explosion to be honest.

you just need to take the blue one off to investigate.

after you take the UIM off, you can just jumper the test fp pin, turn the key on, and check for leaks.

You've got a bad injector o-ring seat on the primary rail more than likely. The upper one on the injector.
The bucking is from a lack of fuel, caused by the leak, so your ECU is trying to compensate for it and hence your bucking. No fuel, computer compensates for it by closing the throttle body. You end up with a bucking cycle until it is at a normal AFR.
Now it could be a line connection on the primary rail too. Be sure to check all of those too.
But I think if you just turn on the ignition, you should be able to tell where the leak is. Use a scope if you have one. And also have a fire extinguisher handy.

cars don't explode, but running in circles while on fire could theoretically happen.

also contrary to belief, smoking while working with fuel is perfectly acceptable but working with fuel while holding a lit torch might result badly.

Ok, Ill go through some things on Saturday and check that out... Looks like this should be not to bad of a fix considering what I thought has happened. I honestly believed that I have blown a seal and my engine was toast =_=


:evil_laug See... I would be the idiot that would light myself ablaze and run around in circles

If it turns out to be a bad seal on an injector, I would suggest changing all the injector seats and seals, primary/secondary, at the same time. You're in there. Might as well do it now.
Save yourself the trouble should another one fail.

I could not find the correct injector seals anywhere around ft worth. Before pulling the fuel rail i would just order 4 seal sets from atkins. The lower seal is easy to damage when installing the fuel rail.

Damn Easy you best me to it

Yes Grasshopper. :rolleyes:

your local mazda dealer probably has the proper injector seals in stock.

if it turns out to be the rails or lines, they would probably be special ordered though.

It's funny you mention that... I have noticed that my clutch peddle slightly wiggles when I shift at an angle or put my foot on the clutch pedal and move my foot from side to side it will wiggle a bit... I know the clutch assembly is under warranty until the end of August this year... think I should go have it looked at and claim the warranty?