[SharkH8R]

Hello all,

I am a longtime viewer, but I don't comment very often. I could use some help though. My car is misfiring in cylinder one with the following code:

29CD:
29CD misfirings, cylinder 1
Error will cause a warning light
Error is not currently present
Test conditions have been completed
Signal or value below threshold

Freeze Frame Information
Event 1Odometer 135832kms 84402miles
Engine temperature 49.50 °C
maximum rpm at missfire 1,600.00 rpm
maximum relative load at missfire 58.98 %
minimum relative load at missfire 32.81 %

Event 2Odometer 135832kms 84402miles
Engine temperature 26.25 °C
maximum rpm at missfire 2,048.00 rpm
maximum relative load at missfire 82.03 %
minimum relative load at missfire 31.25 %

Event 3Odometer 135832kms 84402miles
Engine temperature 37.50 °C
maximum rpm at missfire 1,440.00 rpm
maximum relative load at missfire 99.61 %
minimum relative load at missfire 43.75 %

The vehicle has approximately 88k miles and has not had any engine repair, just basic oil/filter changes. The engine is running very rough, but came on suddenly. I drove the car a few miles in the morning, a few hours later when I restarted the car, this occured. I have restarted it a few times during the last few days to see if it would correct itself, but to no avail.

I have a bavarian technic cable that I have connected to my laptop in order to pull the code. This software can do some wonderful things, I just don't have a clue how to do them. Can anyone give me some recommended steps to resolve the problem?

Andre'

[ctuna]

If you haven't changed them once in the lifetime of the car yet.

[OdomPHD]

Defective ignition coil, perhaps.

[SharkH8R]

I haven't changed the spark plugs yet, I am going to go ahead and do that tomorrow. Since the misfire came on so quickly, I don't think that's the problem.

[MCOChuck]

My money is the ignition coil failed, which is common.

Cylinder 1 is nearest to the rad.

Clear the code then swap the coil with cylinder 2 (zero tools required). Start the car and if the code comes back for cylinder 2 (you’ll likely need to put the engine under some load to get it to throw a code again) than your ignition coil failed. If it stays with cylinder 1 than it’s likely your sparkplug or injector. Clear the code again and swap plugs between cylinder 1 and 2 and see if the problem follows the sparkplug.

Assuming it’s an ignition coil because that’s most likley, if your build date is up to 03/2006 you need BMW part number 12 13 7 594 936 or part number 0221504465. AutohausAZ.com has them on sale for $25.24 ea. If it’s built after that date then go for 0221504470 for $42.72 ea. Also buy a spare to keep on hand.

[roberts5831]

had the same issue, MCOChuck is right on the money.. i did what he said and found out that it was the plugs.

[SharkH8R]

You were right, I moved the coil and the problem occurred in the new cylinder. Since I have the car dismantled, can you guys recommend some new plugs? Also, which air filter should I get? I see one for automatic air, I'm not sure if I have that. I can set temperature for either side, but that's it.

[SharkH8R]

MCO,

Thanks for your recommendation, the new coil pack did the trick. While I was in there, I went ahead and replaced both air filters. I am going to wait to do the plugs when I hit 100k. Now, time to clean out the windshield wiper fluid tank. I think I have some algae buildup...

[mhenry7]

Originally Posted by lataste

MCO,

Thanks for your recommendation, the new coil pack did the trick. While I was in there, I went ahead and replaced both air filters. I am going to wait to do the plugs when I hit 100k. Now, time to clean out the windshield wiper fluid tank. I think I have some algae buildup...

For what it's worth, I just had the same thing on cylinder 2. Replaced coil, got it back together and had the same problem so I figured I screwed something up. Nope, cylinder 1 was throwing the code this time. I read somewhere that bad plugs could put strain on coils, so I switched out the coil and the plugs as well this time. Plugs looked good, but cyl 1 and 2 plugs didn't seem to be torqued very tight and oil was much higher on threads than the rest. Not sure what it means, just noticed a difference. All has been well since. 72K.

[Tim M]

I had this problem. It was an engine coil.

[yakev724]

Guy is selling 3 coils for cheap in the engine FS section. Someone should pick up some spares!

I keep a brand new one in my glovebox.

[TheTal0n]

spark plugs are fairly cheap at autozone, and easy to DIY, coils are just about the same, very quick and easy DIY!

[sanju]

My 2006 325i (50 k Miles) is having starting problems, will start after 3-4 try. "Service Engine Soon" yellow light is on. Car drives well, but there is sudden shaking sometime when starting.

Just put New OEM BMW Battery, so this is not the issue. Cleaned & swapped the solenoids as well.

Auto Zone OBD II check said Code P0301 Cylinder 1 Missfire !

Could this be No. 1 cylinder Bad iginition coil ?

[yakev724]

^^ Yes. Change the plugs if you haven't. They're $70-80 online (NGK Lazer Iridium or Bosch).

[BMTroubleYOU]

haha don't change nothing ..even oil.. lol.. poor cars
step 1 replace plugs, step two (same time) replace coil #1.
...
poor car...

[Chriztofor]

Op, oem plugs can be had at o'reillys for $40 http://www.e90post.com/forums/showthread.php?t=543384

But you also need to change a coil.

[sanju]

Thanks Guys, today I got one ignition coil from dealership for 65 bucks. Interestingly I was able to get the engine cover off without taking off the Air filter using a L shaped T40. Also the Engine Oil Cap remains when the Cover is taken off on my 2006 325i.

Should I just first try replacing the 1st Coil & see before changing spark plugs ? Because changing all the spark plugs will be more work & will involve removing some assembly over the engine, I know though how to remove Air filter assembly, but the plastic parts below that looks difficult.

If lets say the 1st spark plug is bad, will the new coil i put over it get ruined. Is it Ok to just change 1 spark plug, because that is easy to work with ?

[blingman]

if you need the car up and running in a hurry then replace the coil pack for cylinder one and start it up. if it starts fine and idle well, you're good. but I'd recommend replacing all spark plugs eventually. if its a bad spark plug, installing new coil pack is not going to mess it up.

[sanju]

Thanks Blingman for good suggestion. Do you think changing just one spark plug & starting engine will be OK too ? in case spark plug No. 1 is bad. Then after that I will go ahead & change all spark plug.

I am in no rush, have 2 other working back up cars.

[blingman]

Originally Posted by sanju

Thanks Blingman for good suggestion. Do you think changing just one spark plug & starting engine will be OK too ? in case spark plug No. 1 is bad. Then after that I will go ahead & change all spark plug.

I am in no rush, have 2 other working back up cars.

changing just one is okay too, they work independently so it wouldnt affect the rest, just good measure to change them all at the same time since they're cheap.

[sanju]

Thanks again, will do this & report.

[sanju]

OK, I first changed the 1st Ignition coil with new one, did not improve starting the car. Then changed the 1st Spark Plug & new coil- little improvement
Changed all spark plugs, little improvement in starting.

Car is driving a little better & smooth ! but starting problem still persists.

Any comments ? Service Engine Soon light still on.