Engine Misfire

[vs69]

What's up guys, I'm having misfires in cylinder 6 and 8 on my e39 540i, anything I should be looking at besides spark plugs....I hope it doesn;t mean too much $$$$$$.

[TheMadChigga]

swap the spark boots, if it goes away, go buy new boots.

[O.S.]

coils, try switching coils between cilinders and you will see if the missfiress will move to the new location ... thus you'd be able to identify if the plugs are the problem or the coils and which ones.

[vs69]

I'm going to try swapping my friends coil packs and see if they work on his bimmer and see what happens. Then we'll know for sure if it's the coil packs or what not.....thanks guys, I appreciate it. I'll keep you up to date.

[NOTORIOUS VR]

many times it's just the boot's on the end of the coils... so I'd suggest testing the boot thing first as the mad chigga said... it's a lot cheaper then buying new coils that you don't need.

[vs69]

Just to keep you guys up-to date, I went to a BMW shop, the mechanic told me that he cannot further diagnose the misfire's until I change the "cats" and I have 2, the price is roughly 1400$ each, plus install. I personally think it's the "cats"t also because when driving normally...lol on the street reving at 2500rpm;s it;s fine, but the minute I step on it to pass someone, right off the bat at 4000rpm's, you can tell I'm running on like 3 cylinder;s. So I'm thoughts on this are, my cat's are blocked and they rattle like crazy, so they are FINISHED. I'm aiming at getting Magnaflow's for now. After changing those, hopefully the misfires will go away, if not spark plugs and then coil paks and boots.

[Quack]

I had a severe misfire problem with my 540 because of clogged cats, had the same problems to, I can drive fine in the city but when I try to pass someone on the hwy the car would start to misfire, I ending up getting Brullen Hi-Flow cats for $150 each & a whole new cat-back system from Brullen for $1200, problem with the Hi-flows cats almost caused me to fail emissions

[vs69]

I just don't understand how both my cats could've gone bad within a couple months, what was and what am I doing not right?

[Quack]

you mean you had them replaced a couple of months ago already?

[vs69]

no, but I bmw cats aren't normally supposed to go. I mean other vehicles like toyota's, you might expect a rusty cat needs to get changed. So I've been told anyways...I don;t know.

[Quack]

euro car cats go more often than cats from Japanese & domestics, I don't know how many times I've seen cats go on BMW/Benzs/Audi/VW, it's a common problem

[RMPMOTORS]

Your missing is on the same bank, only one cat can be the culprit.


Rocco

[Quack]

he might as well replace both, most likely the other one will go soon, and besides if he goes aftermarket cats they are like $100-$200 each

[EugeneBMW]

I just got my 2000 M5 and am experiencing the same problem. driving at a constant RPM is fine but while accerating at lower RPMs, my car jerks as if its lacking power (not something i would expect form this car). I was thinking to clean the throttle boddies, but aside from that, i dont really know what i can do. Any advise?

[vs69]

Well, I'm finally going to the garage tomorrow morning to change the cats. I'm getting installed 2 Magnaflow cats part# 94106 and we'll see what happens there. If my misfires stop, then great news, if not, I'm going after the coil packs and spark plugs. But then again, I don;t want to go that far. Although one night, I jacked up the front end of my car and rattled both cats too see if both were rattling and you can hear both were finished. When leaving that night, I didn;t have any misfires for at least two days. So I honestly think, it's the cats that are clogged. But we'll see tomorrow. I'll keep you up to date tomorrow.