cyl 4 misfire - Miata Turbo Forum - Boost cars, acquire cats.

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Old 04-04-2012, 10:45 PM   #1
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Default cyl 4 misfire

Driving me crazy. Happened on my second run on Sunday. Got back on the gas after turn 2, no power and sounds like a ------- subaru. MIL flashing. p0304. Fluids didn't mix, nothing out the tailpipe so driving home on 3 cylinders wins vs tow truck.

#4 plug is black. Cleaned up and swapped out with another cylinder. p0304. coil swapped. p0304. All 4 plugs spark. Pull upper im, walls are coated with gas. Injectors all measured 13 ohm. Stock measured 12.

Surely it must be an injector then. Swapped the stock back in, put everything back together. p0304. w.t.f


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Old 04-04-2012, 11:06 PM   #2
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Oh yeah. Cam cap was loose
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Old 04-04-2012, 11:07 PM   #3
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Sounds like it might be running rich, and since cyl. 4 is usually the hottest with a stock cooling configuration, it would be affected first. Any signs/sounds/visuals of detonation events? I assume this happened at the track? If you're running so rich that their is gas sitting on the inside of the intake manifold, I'd start looking for things that would cause the ECU to send extra fuel.



FWIW, if you do not clear the ECU between tests, the codes will remain. Don't know if you tried that.
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Old 04-05-2012, 12:36 AM   #4
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yeah i hear that running rich is a common cause of broken camshafts.

Do I need anything to install a new exhaust cam? new caps? Maybe a torque wrench to smash into the shop tech's head that rebuilt my head not 200 miles ago?
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Old 04-05-2012, 03:11 AM   #5
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Almost sounds like injector 4 is shorted open in the harness somewhere.
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Old 04-05-2012, 10:04 AM   #6
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if it's constantly on #4, it has to be the #4 injector, plug, plug wire, or valves/rings.
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Old 04-05-2012, 10:29 AM   #7
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With only 2 of the 3 cams rotating, exhaust valves on #4 never open. yes, I have 3 cams now. See?

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Old 04-05-2012, 10:37 AM   #8
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more cams more powah!
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Old 04-05-2012, 12:04 PM   #9
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Holy ****!!!
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Old 04-05-2012, 12:35 PM   #10
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It's my patented triple overhead cans TOHC (tm). My car is full of win this year. Fully expect it to spontaneously implode when the MS2 gets installed.
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Old 04-05-2012, 01:15 PM   #11
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A little jb weld and she'll be just fine. just make sure its timed right! lol
Holy ---- that sucks.
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Old 04-05-2012, 01:21 PM   #12
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Wow.

What a man you are.
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Old 04-05-2012, 02:35 PM   #13
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snapped cam was going to be my guess...that was until i made it far enough in the thread to get to your photo.
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Old 04-08-2012, 01:03 AM   #14
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Wow. Wow!

So the next question is, after having driven home with the cam faces grinding against each other, are you going to do anything to clean the motor out? Or just clean out the valve cover area and call it good.
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Old 04-08-2012, 06:11 AM   #15
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Quote:
Originally Posted by midpack View Post
LOL @ the camshaft breakage that is obvious, but not so obvious, in the first post of thread. That's pretty crazy.
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Old 04-08-2012, 10:55 AM   #16
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How often does this shi really happen?? And wtffff
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Old 04-08-2012, 11:30 AM   #17
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Maybe the shop that left the cam cap loose 200 miles ago owes you an engine?
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Old 04-08-2012, 04:04 PM   #18
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DAMN! That hasn't even happened to Faeflora yet.
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Old 04-08-2012, 10:05 PM   #19
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Quote:
Originally Posted by Mobius View Post
Wow. Wow!

So the next question is, after having driven home with the cam faces grinding against each other, are you going to do anything to clean the motor out? Or just clean out the valve cover area and call it good.
FM says to have the journals inspected and if trashed buy a new head since that's cheaper than machining and getting a custom cam ground to match. So head comes off and goes to a non-shitty shop. Instead of working on the car I bought a Yamaha Blaster and spent the weekend getting muddy. Maybe tomorrow.

I figured an oil/filter change would take care of any bits of shaft. The small piece didn't look like there was much in the way of damage, but I never looked at the big piece. 200 miles is a common OCI right?
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Old 04-08-2012, 10:08 PM   #20
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Quote:
Originally Posted by hornetball View Post
Maybe the shop that left the cam cap loose 200 miles ago owes you an engine?
Yeah about that. Told me to leave and never come back when I asked about getting $72 for a headgasket they cost me by doing a shitty job on intake valves that leaked after a valve job. Called them last week to see if they wanted to have a discussion, was told there were customers there and would call back in a few minutes. That was Thursday. I'll give it one more try and next time they hear from me will be in small claims. cocksucking ----------ing piece of ------- ---- ********.
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