Misfiring cyl 4

Bronson9856

Bronson9856

Greenie N00B Member
hello everyone,

I did a bad thing. My Speed3 is having a misfire on cyl 4. I was in it yesterday and was getting on it on the highway, when I got a puff of black smoke out the back and it has been running really bad since, misfiring on cyl 4. I'm guessing I blew something up, but not sure where to begin. I have taken off the tmic and removed the spark plugs. . 3 of the cylinders spark plugs have white buildup, the 4th has black wet buildup. I'm thinking maybe I blew some rings or something?! Does anyone know a good speed shops in the Cincinnati, Ohio area that can help me with this issue? Thanks in advance.
 
Is it modded? Do you have a method of logging anything?

Safe to assume you don't have a way to perform compression / leak down tests?
 
It is modded, i have a cobb tuner. The engine is not getting too hot, i have ordered a compression check kit, but it will be a week or two to arrive.
 
What mods? Mileage on engine? Who created the tune? Info about tune as well if you know details.

Do you know the basic steps to take an idle log, and what parameters to include?
 
It was modded by me and tuned by DIZZY tuners. It was running really good for about a year now, but was burning a quite a bit of oil(Which there were no visible leaks). When I had it to the floor on the highway, it seems like something "blew" and a black puff of smoke went out the back and has been running really really bad, misfiring and running "rough" only on the acceleration, when I decelerate it sounds "OK". I will collect some idle logs and see if I notice anything, and get a compression test. I will upload all the data I can get. As far as what to log, I will keep the same parameters that my tuner asked for.
 
Get a log of the issue and post here. Take some pics of the plug if you can and a video as that would help to hear it.
 
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How far "into it" would I have to get to find out? I probably need some help from somebody who knows what they are doing. I can do a lot of stuff, but rebuilding the engine is a little over my head.
 
Does anyone know if any 2.3L turbo engine will work? I know they put those in cx7s too. Would a 2008 go into a 2010?
 
There cx7 will work. It's pretty much the same as the gen 1 Mazdaspeed 3. You do need to be careful with them as most of them are not well maintained and oil coated valve train. It needs to be there turbo 2.3 not the NA 2.3
 
I talk to my family mechanic and he said that it is possible that I just have a blown head gasket. Is there a way to tell if it is the head gasket and not something else? It turns over with no knocking and weird sounds.
 
Hey dude, I had something really similar happen a few years ago. Partial throttle acceleration onto eway then all off a sudden an aggressive rattling noise, car drove like shit, carbon out the tailpipe. Had a borescope so took a look down into my cylinder and one or two of them had a ton of pitting in the faces of the piston. Confused as hell, I pulled the head and found that one of the VALVE SEATS shattered. I can only assume something happened that lead it to lean out, and by the sounds of your white spark plugs, same for you. car sounded fine when decelerating, but the second I would go to put load on it, sputtering.

Here is a pic to show you what I mean. Hope for your sake this isnt the case, but its a great excuse to spend way more money than you want and end up with a really fun car. That tiny little piece of metal forced me to get a new cylinder head, sleeve the block, and all new pistons, which required all new rods. Hope it is your headgasket but the only way to know is taking the head off.
 

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Bronson9856 said:
I talk to my family mechanic and he said that it is possible that I just have a blown head gasket. Is there a way to tell if it is the head gasket and not something else? It turns over with no knocking and weird sounds.
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There are ways to test for a blow head gasket but you will want to do some googling. I have not had to look into that before.

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The low, almost nonexistent compression on 3 and 4 and excellent compression on 1 and 2 do tend to cause me to lean toward a blown head gasket. But, that is usually secondary to over heating.
 
Look for oil in your coolant or coolant in the oil, almost always have one or the other with a bad head gasket.

Significant long term oil loss sounds like rings to me.
 
ajkulish said:
Hey dude, I had something really similar happen a few years ago. Partial throttle acceleration onto eway then all off a sudden an aggressive rattling noise, car drove like shit, carbon out the tailpipe. Had a borescope so took a look down into my cylinder and one or two of them had a ton of pitting in the faces of the piston. Confused as hell, I pulled the head and found that one of the VALVE SEATS shattered. I can only assume something happened that lead it to lean out, and by the sounds of your white spark plugs, same for you. car sounded fine when decelerating, but the second I would go to put load on it, sputtering.

Here is a pic to show you what I mean. Hope for your sake this isnt the case, but its a great excuse to spend way more money than you want and end up with a really fun car. That tiny little piece of metal forced me to get a new cylinder head, sleeve the block, and all new pistons, which required all new rods. Hope it is your headgasket but the only way to know is taking the head off.
Click to expand...


Thanks for the reply, I'm towing to the mechanic after memorial day(cause he is backed up). I guess I will then find the extent of the damage, wish me luck!
 
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