Engine misfire and power loss

[vimal32]

Hi all,

So lately I've been having what feels like a misfire on my 2000 320i (6 cyl Manual), especially under load, ie when going uphill and also when in a high gear at lower speeds.

Here is what I've done/checked so far :

*Changed all 6 spark plugs (feels alot better after 2nd gear, jerkiness was much worse on the old plugs),
*Changed the fuel filter.
*Tried checking and cleaning the ignition coils - left car running at idle and disconnected 1 coil at a time to see if I could eliminate if its a coil problem. Each one I disconnected dropped the engine's RPM, so I'm assuming they are connected properly and working since there was a reaction when it was disconnected.
*MAF and Idle control valve connected/disconnected - No difference to the misfire.
*Removed, cleaned, tested the fuel pump, all seems perfect.
*Checked the vacuum hoses and no cracks.
*Disconnected the battery for 10-15 minutes after each step to clear any saved codes.

I'm hoping you guys can suggest what else I could check.
Unfortunately I don't have a code reader - can anyone in JHB area, pref West Rand or South help me read the codes if you have a reader?

Will appreciate any and all suggestions.

 

[whattingh]

Coder reader is the best place to start.
Also bit more info like kms on the car etc. double vanos?

Off top of my head:
Disa value seal could have airleak.
O2 sensors
cam sensors
vanos troubles have alook here http://www.beisansystems.com/

error codes would help eliminate lot of possible cause quickly

 

[vimal32]

Thanks whattingh,


Car has 218 000 KM, It is a 320i 2000 model(pre facelift, 6 cyl, 2L engine with double Vanos).

I guess that is the best place to start.
Can anyone assist me to get my codes read? I dont mind driving out to wherever you are at a convenient time for you.
Please help...

 

[Major]

Checking your coils isn't a matter of looking at them or removing them. They might work just fine at idle. You need to find someone with a working set and replace all of them, then go back to the old ones one-by-one until the problem comes back. Unless you have a codereader, then you can just find the cylinder with the misfire, and just swap coils between two cylinders (one with a fault and one without) and see if the fault appears on the swapped cylinder.

The fact that it got better after changing your plugs, but it's still happening, makes me think that a spark plug was fouled by over-fueling, thanks to a bad coil. Changing the spark plug helped bring back some life, but the cause is still there. I'm calling coils!

-EDIT- I forgot to mention that you can just borrow one good working coil, and test drive your car 6 times with the coil in different cylinders. This will pinpoint a bad coil if it's just one of them.

 

[moranor@axis]

major thats an awesome diagnosis

 

[Major]

major thats an awesome diagnosis

Only if it's correct. vimal32 are any one of your old sparkplug ends coloured differently from the rest of them?

 

[Raybimmer]

What about testing the resistance of each coil with your multimeter ? All should give similar readings , check to see if they are close to spec .

 

[vimal32]

Checking your coils isn't a matter of looking at them or removing them. They might work just fine at idle. You need to find someone with a working set and replace all of them, then go back to the old ones one-by-one until the problem comes back. Unless you have a codereader, then you can just find the cylinder with the misfire, and just swap coils between two cylinders (one with a fault and one without) and see if the fault appears on the swapped cylinder.

The fact that it got better after changing your plugs, but it's still happening, makes me think that a spark plug was fouled by over-fueling, thanks to a bad coil. Changing the spark plug helped bring back some life, but the cause is still there. I'm calling coils!

-EDIT- I forgot to mention that you can just borrow one good working coil, and test drive your car 6 times with the coil in different cylinders. This will pinpoint a bad coil if it's just one of them.

Hi Major,
Thank you very much for providing exactly what I was looking for.
A well thought out response - much appreciated.
Yesterday I managed to buy 1 second hand working coil and doing the 6 test drives is exactly what I'm doing
I put it into cyl 1 today and drove to work - misfire is still there, so i will change it over to cyl 2 tonight.
I should know by the end of the week if I have resolved this issue.
If it inst fixed by the end of the week I'll just get the damn codes read at some service centre.

The old spark plugs were all black - I cleaned them out as much as I could and put them all back in - drove around for 2 days to see if I could see different colours to find the problematic cyl. No luck, all were completely black again. It does look like all were fouled by over fuelling.

I'm very certain that it is a coil issue.
Will keep you guys informed on my progress or lack thereof.

@Raybimmer, I dont have a multimeter handy, so going to try the 1 cyl at a time thing to see if I can resolve the issue.

Thanks once again to you guys for helping - you guys Rock!!!:excited:

 

[Beast_Power]

Without reading the codes this is going to be a very lengthy and possibly costly process to say the least.

 

[vimal32]

Update:
I got the codes read - thank you Gizmo...
Cyl 5 had a misfire, changed the coil and everything is running smooth again.

Gizmo test drove my car too, and said it felt quite low on power - could possibly be a blocked Cat converter or O2 sensors going bad.

I will be taking it to the mechanic recommended by Gizmo when I get the time...

Thanks to those that contributed constructively...esp Major and Gizmo.

 

[Major]

Only saw this now, glad you got it sorted! :thumbs: