So my check engine light has been on for a little while, and I had the codes read, and this is what comes up:

"Cylinder 5 misfire, Multiple/Random Cylinder misfire, Catalyst defficiency left bank."

So I decided to start a little bit of a tuneup to no avail.
I replaced the spark plugs, valve cover gaskets, fuel filter, and I cleaned the MAF and also did a fuel system treatment with the BG44k.

It seemed to help, and for a few days the SES light stayed off, now it is back on and it is not running very well again.
It seems to me like it is some sort of sensor problem... the engine sounds smoothe internally, it just cuts out sometimes or sputters in low rpm's.
Any ideas?? I need help so I don't have to keep replacing random parts...
Thanks.

Bad ignition coil. Swap the #5 ignition coil with another and see if the fault code follows. If it does, bingo; you have a bad ignition coil. Which I'm positive it is that.

but would one bad ignition coil cause the "random multiple misfire"???
I understand your point for the number 5 cylinder...but what about the random code that comes up?

Well if I have to replace an ignition coil or two, does anyone know if the Bavauto "performance" ignition coils are worth the $600 asking price?

I had the same symptoms and codes when my MAF was going/went bad. Sorry to say it, but it might be giving up the ghost on you.

Anybody have any experience with the bavauto coils?

My first suspicion, given the faults, would be an intake leak or bad CCV. Until that was ruled out as a cause I would not consider replacing coils. And unless the car has been fitted with an oiled air filter the MAF is not likely to be involved. If the car has or has had an oiled air filter (commonly a part of a CAI) the MAF is likely to be a player and may need to be replaced.

If the pre-cat O2 sensors have more than 80K on them, they may be contributors. And if they have 100k on them replacement is required.

I have a k&n oiled filter...but i just cleaned the MAF, so I'm not sure it's that. Plus the problem seems to get worse once the car is warm and has been running a while, like the heat is building up resistance in something electrical...which is why the coils would make sense. Or at least one of them

Cleaning the MAF does not guarantee the problem is eliminated. Cleaned mine, or so I thought, but remedy was replacing the MAF (AT 76,000).

The thin film sensor in the MAF can reach temperatures that will polymerize or carbonize organics, which then cannot be removed from the sensor. If that's happened, only replacement of the MAF will restore normal operation. When the stock airbox and filter are used there's essentially no chance of contaminating the MAF, but if you fit an oiled filter the MAF will fail at some point.

hmm...well I hope it's not the MAF, that's a bit more expensive than just one coil. But since I can't be completly sure of anything I guess I'll have to take it somewhere to be correctly diagnosed. Thanks for the input

Well i switched out the #5 coil with another, but the code still stayed with the #5 cylinder. Also, today the code went away completely for a while, and the car ran great...then it came back on, then it went off, and now it's back on again. When I went to have the codes read again, the other 2 codes were gone, but the cylinder 5 misfire was still there??...Hard acceleration seems to agitate it. Does that info help diagnose anything??

yeah i was gonna say the MAF sensor but idk. did you clear the codes btw?

i didn't at first, i know i should have but forgot. I did just a bit ago so I'll have to wait till the light comes back on i guess. I also cleaned the MAF again, for good measure, this time I let it dry for an extended period of time. I'll get the codes read again as soon as it comes back on.

Did you figure out what the problem was?

I am having a similar problem with my '98 528. It has been getting worse and a few weeks ago, the CEL came on (first time ever). I got the code read at autozone and they told me cylinder #2 misfire. I checked all the coil boots, and they were fine, then soon after the CEL turned off.

Last year it was giving me similar problems twice, then I checked the boots (1 was torn), replaced it and it ran fine - for a while.

Now, I've been driving the car more often and in the morning it runs fine, then when it starts to warm up, it runs worse. Same symptoms, it sputters a low rpms and sometimes at idle. Once I get past 2800 rpms it pulls normal. I don't know where to start.

Yah i figured mine out just last week. I had a bad ignition coil. It's a $54 part on pelicanparts.com. I also replaced all of the spark plug boots for good measure. Only $7 bucks a piece.

Your problem sounds like it very well could be the same thing, but it still could be something different. It would be wise to take your car to a shop who can properly diagnose the exact problem and then buy the parts and do the work yourself. This is what I did and it was only a $150 fix including the diagnosis, ignition coil, and all 8 spark plug boots. Proper diagnosis is worth the money.

Ok, thanks. So just out of curiousity. Did you take it to any mechanic shop, or where they specialize in BMW/Euro cars? How much was that charge and they just told you it was a bad coil?

I have replaced 3 of the 6 plug boots in the 3 yrs I've had the car. Last I checked, their weren't anymore that were torn/cracked.

It's due for a plug change due to time only (1.5 yrs) but it's only been driven 3500 miles or so on those spark plugs. Maybe I should check first before shelling out more $$$.

I agree with you. Proper diagnosis is way worth the coin.

I took it to an independent shop, but I still wouldn't just take it anywhere. The place i took mine to is not afraid to tackle BMW's and other foreign vehicles and have done work for me in the past and have always done great work. But I would make sure you talk to the shop and ask them if they are willing and able to do the diagnosis.
Normal time for a dianosis is 1 hour for a shop to charge you. The shop I took mine too quoted me an hour at $80 an hour...but it only took them half that so they only charged me for a half an hour. Or maybe slightly more than half an hour because the bill was $48 bucks. Well worth it.

BTW, spark plug boots are cheap, and if they are bad it doesn't mean that you will be able to tell that with the naked eye. They could be internally bad. I would replace them all, or at leat the ones that haven't been replaced recently.

Yeah, I had thought about that. I will order the other three when I find out what's wrong with the car. Those plug boots are cheap! compared to the wires on my old E34. Something like $152 for the set. :eek:

Cool, thanks for the info. I'll be sure to post up again when I find out what's wrong with the BM.

*Ha!, your sig cracks me up. I also have a Western plow like that, but instead of an E39, it has a beat up Ramcharger pushing it. :)

Ya let me know how it turns out

So, my car seems like it's fixed now. A buddy of mine had an extra igniton coil from his 99 323i. We discovered it's the same coil, so I put it in, and the car has been running fine for the last 3 days. I gave my buddy $40 for the coil, so I'm hoping that was the problem. Now I just gotta get the CEL removed. :redspot

sweet, it's always nice when such a bad driveability problem like that is such a cheap fix.