[mmurray]

On my way to work today, I noticed a slight hiccup when accelerating through 2nd, and a few miles later on the throttle it happened again. Then CEL came on and it got real rough so I put it in neutral, coasted to a stop and turned it off.

Luckily I have an OBDII tool in the car so I checked it and it shows a P0304 (Cylinder 4 Misfire), but when I restarted the car the CEL went away. It drove home without the rough firing feel I got after it first lit up, but I have felt the occasional hiccup at idle so I don't think this is a one-time issue.

I have a 90mi daily commute so I'm trying to figure out how to fix this so I can get back on the road ASAP - what's my best bet for a first fix... plugs? coils? I'm probably due, but wouldn't know where to start. Has anyone experienced this/ know how to address it?

I found this old thread (http://www.e90post.com/forums/showthread.php?t=435364), but the linked diagnostic chart looks to be N54 and I don't fully understand it anyway. Any help would be HUGELY appreciated at this point!

[Bavarian Tech]

Just replace the coil, and be done. Wouldn't hurt to replace the plugs if they have near 100k.

[TittoBlunt]

Swap it with another coil and see if the issue follows the coil. If it does, replace that coil. If not, could be the spark plugs. How many miles do you have? If you're around 100k, I would just replace them all (coils and plugs). Easy DIY.

[mmurray]

Originally Posted by Bavarian Tech

Just replace the coil, and be done. Wouldn't hurt to replace the plugs if they have near 100k.

Originally Posted by TittoBlunt

Swap it with another coil and see if the issue follows the coil. If it does, replace that coil. If not, could be the spark plugs. How many miles do you have? If you're around 100k, I would just replace them all (coils and plugs). Easy DIY.

Thanks! What I figured, but didn't know if I should start checking elsewhere for related issues. I don't have any of the parts handy, but need to be back on the road tomorrow so looks like I might have to get bent over at the dealer rather than do Tischer. Any idea what I should expect to pay?

I'm up almost at 180k, but the previous owner (supposedly) replaced them around 100. Do I need any special tools to do plugs/ coils? AKA can I do this with parts and sockets tonight?

[Bavarian Tech]

Assuming you have an N52 with the silver engine cover. You literally don't need any tools to do a coil on #4. U can do it the parking lot. Maybe you might need to use the flat head screw driver in the trunk to "unplug" the coil. Personally if your close enough to a local dealership just go there n get a coil from the parts department (Under $100) . You can drive the car with a misfire, the DME de-energize the fuel injector so its not dumping raw fuel into the cylinder. Might drive a little rough but other than your fine.

Here's the DIY for spark plug if you decided to do it
http://www.e90post.com/forums/showthread.php?t=174217

[mmurray]

Originally Posted by Bavarian Tech

Assuming you have an N52 with the silver engine cover. You literally don't need any tools to do a coil on #4. U can do it the parking lot. Maybe you might need to use the flat head screw driver in the trunk to "unplug" the coil. Personally if your close enough to a local dealership just go there n get a coil from the parts department (Under $100) . You can drive the car with a misfire, the DME de-energize the fuel injector so its not dumping raw fuel into the cylinder. Might drive a little rough but other than your fine.

Here's the DIY for spark plug if you decided to do it
http://www.e90post.com/forums/showthread.php?t=174217

Picked up a coil at the dealer, but went to check the coils using this procedure (

) by disconnecting each during idle, but all of the coils -including the 4th and suspected problem- made a difference so I don't think any are dead.

What's next, spark plug? Really trying to do this tonight but I missed my window for OEM stuff, I'd have to go to AAP soon

[GoRomeo]

Originally Posted by mmurray

Picked up a coil at the dealer, but went to check the coils using this procedure (

) by disconnecting each during idle, but all of the coils -including the 4th and suspected problem- made a difference so I don't think any are dead.

What's next, spark plug? Really trying to do this tonight but I missed my window for OEM stuff, I'd have to go to AAP soon

Check for vacuum leaks. I recommend you cross tighten the gasket starting from the inside out. Equal and in a pattern will result in a good seal.

[mmurray]

Originally Posted by GoRomeo

Check for vacuum leaks. I recommend you cross tighten the gasket starting from the inside out. Equal and in a pattern will result in a good seal.

Can you explain a little more what this means... Are you talking about the aluminum bolts around the valve cover?

[GoRomeo]

Originally Posted by mmurray

Can you explain a little more what this means... Are you talking about the aluminum bolts around the valve cover?

Yes, not sure if you have replaced your VCG but someone here was getting same error code (P0304) and posted that the back of the valve cover (where you can't see it), directly behind each cam, there is a half moon opening that is closed off with half moon pieces on the gasket itself. When he installed the gasket he inadvertently bent over one of the "half moons," thereby causing a huge hole/vacuum leak. If not, it does not hurt to check for leaks around the hoses etc...

[mmurray]

Originally Posted by GoRomeo

Yes, not sure if you have replaced your VCG but someone here was getting same error code (P0304) and posted that the back of the valve cover (where you can't see it), directly behind each cam, there is a half moon opening that is closed off with half moon pieces on the gasket itself. When he installed the gasket he inadvertently bent over one of the "half moons," thereby causing a huge hole/vacuum leak. If not, it does not hurt to check for leaks around the hoses etc...

Thanks though - I didn't see that issue when I search the code. I didn't, but I suspect the previous owner did (VCG is red not factory silver). Is the half moon you're talking about those little parts of the gasket that stick out? And if they're bent externally does it matter?

Also any idea on the torque for those aluminum bolts? Really don't want to botch those.

[mmurray]

Still getting issues on open throttle, and it threw codes again tonight and felt like it shut a cylinder down while I limped home. I had the new extra coil so just swapped it in. Also tried tightening the gasket bolts a little but was worried about over torquing and couldn't get to the back ones (even with flex/ extensions).

Going to drive a bit now and see what happens... Any reason I shouldn't drive without the silver cover for a bit while I test? For quick coil access.

[Taskmaster]

Originally Posted by mmurray

Still getting issues on open throttle, and it threw codes again tonight and felt like it shut a cylinder down while I limped home. I had the new extra coil so just swapped it in. Also tried tightening the gasket bolts a little but was worried about over torquing and couldn't get to the back ones (even with flex/ extensions).

Going to drive a bit now and see what happens... Any reason I shouldn't drive without the silver cover for a bit while I test? For quick coil access.

Just happened on mine. They will all go soon, just replace them all. And you don't need to drive with the cover on.