CEL: cylinder #3 misfire

[localkineguy]

Hi guys,
Since changing my coils, wires, and plugs, I've been getting periodic CELs telling me that cylinder #3 is misfiring.
The details:

• I have 106,000 miles on the car
• no noticeable symptoms like decreased mileage, power, etc EXCEPT for a rough idle during the first few minutes of start up
• after clearing the CEL it won't come back for another 200-400 miles
• I've already retightened the spark plugs and made sure connections were good but I did not actually pull the plugs out to check them
• I can do a compression test and will soon have access to an Actron CP9145 autoscanner

any ideas on how to fix this?

 

[slavrenz]

Sounds like you've either got a bad fuel injector at this location or a leak at the intake manifold gasket. Try swapping your injectors (only swap for the same color), and see if the misfire follows the injector (i.e., if the injector is bad, you'll instead get a code for Misfire Cylinder #4).

 

[localkineguy]

is swapping injectors a fairly easy task?

 

[slavrenz]

is swapping injectors a fairly easy task?

yes. look in the service manual (available at the top of this forum as a "sticky") for exact instructions.

 

[P-Funk!]

Me?
i would pull and inspect the plug. Give us a picture if you can.

I would then swap the coil with the other one to see if the problem moves. Then move the spark plug.

It is not impossible to get a new/bad component.

 

[localkineguy]

By the way, which cylinder is #3?

I'll pull out the plugs tonight and have a looksie. Weird thing though, my CEL has turned off...WTF?!
Do CELs turn themselves off? I'd like to reiterate here that I haven't noticed any problems with the car except for a rough idle for the first 20 seconds at start up and a corresponding small puff of smoke.

 

[P-Funk!]

Codes reset automatically after three(?) cycles without the code being found. This is so a spurious code is weeded out. You can still read the code if you pull it.

Vacuum leak (PCV?) at #3?

Stuck injector (running rich?) could explain the puff of smoke...

 

[localkineguy]

still haven't figured out which is cylinder #3 so I just pulled the two middle plugs...
here's the one on the passenger side-mid: <table style="width:auto;"><tr><td><a href="http://picasaweb.google.com/lh/photo/XyMa3REXiPSuLQ-WsPWuUA?feat=embedwebsite"><img src="http://lh4.ggpht.com/_8wgWoX2iGaY/S6rSfzFmRPI/AAAAAAAAZCc/wJUcCkecQ_I/s144/P3243996.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="http://picasaweb.google.com/localkineguy/MazdaProtege5?feat=embedwebsite">Mazda Protege5</a></td></tr></table>

and the other:
<table style="width:auto;"><tr><td><a href="http://picasaweb.google.com/lh/photo/9LlEDkddcNaSd0sREzjeYA?feat=embedwebsite"><img src="http://lh6.ggpht.com/_8wgWoX2iGaY/S6rSeHbDBnI/AAAAAAAAZCU/6-abIjoNPZA/s144/P3243991.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="http://picasaweb.google.com/localkineguy/MazdaProtege5?feat=embedwebsite">Mazda Protege5</a></td></tr></table>

and the two: <table style="width:auto;"><tr><td><a href="http://picasaweb.google.com/lh/photo/0fxLm0Fby0Phxo3PKRLGdg?feat=embedwebsite"><img src="http://lh3.ggpht.com/_8wgWoX2iGaY/S6rSYtJi-KI/AAAAAAAAZCE/Fx5BGu4Snyk/s144/P3243986.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="http://picasaweb.google.com/localkineguy/MazdaProtege5?feat=embedwebsite">Mazda Protege5</a></td></tr></table>

I've switched the coils so maybe the misfire will move cylinders. I'll keep you all posted, but as long as the CEL is gone I'm not too worried

 

[P-Funk!]

Plugs look good. It is truly a random misfire.

Both are gapped correctly, i assume.

 

[localkineguy]

Both are gapped correctly, i assume.

Uh...I assume so too? I don't know.

Anyway, I took it to my local mechanic and he's thinking that I have a bad head gasket because

• switched the ignition coil packs around and the new CEL that came on still read cylinder #3 misfire
• rough idle at start up
• small white puff of smoke when I get into gear and actually start moving
• slowly decreasing coolant level despite no obvious leaks onto the ground where I'm parked
• slowly decreasing oil level, again no obvious leaks

He's going to pressurize the system tonight, then take a look into the cylinders tomorrow to look for coolant and/or oil.

That being said, how much does it cost to replace a head gasket? I know it's going to be a lot.
Also, I was looking into the service manual about how to replace it...holy crap. Do any of you guys have experience doing this? I'm not afraid to get in there and start doing this project but I don't think I have the right tools...mainly to take off the timing belt. What specialty tools, if any, do I need to do this head gasket replacement job? This may be appropriate for a new thread

 

[jdmdikk]

i kept gettin random and missfire cyl 3 or 4 or both and it was my egr valve,i replaced the egr and everything was normal again

 

[bucksatan]

By the way, which cylinder is #3?

On most 4 cylinder engines the cylinders are numbered from the timing belt side. So cylinder 1 is next to the timing belt and 4 is at the end away from the timing belt. In the case of our cars, 1 is on the passenger side.

 

[localkineguy]

On most 4 cylinder engines the cylinders are numbered from the timing belt side. So cylinder 1 is next to the timing belt and 4 is at the end away from the timing belt. In the case of our cars, 1 is on the passenger side.

Cool thanks.
Update: I've taken the car to a mechanic and he says that I have a bad head gasket. He pressurized the system and let it sit overnight, pulled the plugs and sees coolant in the cylinder .

 

[slavrenz]

Cool thanks.
Update: I've taken the car to a mechanic and he says that I have a bad head gasket. He pressurized the system and let it sit overnight, pulled the plugs and sees coolant in the cylinder .

Sucks to hear man, sorry. You've got two options - head gasket replacement or new engine. Depending on your current engine's mileage, it may be more economical to swap it out with a low miles used engine.

As far as the actual gasket replacement, I've done my timing belt, but I've never pulled the entire head. I can tell you that if you are good at following instructions and working carefully, I don't think it would be a bad DIY job.

 

[localkineguy]

engine has 106,000 miles. So far I've been quoted $980 by Pep Boys just for the replacement, not including any machining of the head if it's been warped. Where's a good source for a new engine, I'm in Delaware...

 

[bucksatan]

Check local wreckers, or car-part.com. Up here near Toronto used FS-DE engines tend to go for about $500 or $600.