Help, backfiring and no power

[Y2KSierra]

The car (95 3.4 M5) has always burnt through 02 sensors and had suity exhaust tips since I first got it (43k miles) It is now at 100k miles and it hasn't been running correctly for some time. It's always idled a little rough, been sluggish (it is a 3.4, so I thought this was normal), and generally been weird. It has never let me down though so I thought everything was at least in decent order. Last week the car started idleing horribly, would surge from 500 rpms to 2000, etc. etc. Turned out I replaced the idle control sensor and then everything seemed great. Ran better than it ever had before that I could remember. That was one day ago.

Now (today) it started having no power (like half of what it had) and is backfiring like mad, missing, and running extremely rough, when it idles you can hear various things in the car shaking as well as the exhaust. The best way I can describe it is that it is shaking like a small block with a wicked cam put into it. What is going on here? 101k miles on it, is the engine going on me? What should I look for/replace to get it running right again?

ANY help is appreciated,

Thanks,

Steve

[Whitey]

Stave, what is the service record of your car?

My 94 M5 has 192k and I have not had any of the problems you have mentioned. But i know the regular service was preformed on mine

[Y2KSierra]

I took it in today :( It's going to get a full tune up for one thing since the last one was done at 50-60k miles. Noticed the Spark Plug wires looked like they had been arcing some since they looked burnt in certain places so that might be causing dead cylinders :o Anyway, I'm guessing it needs a full tuneup and possibly some other things, we'll see :(

[ChillPhatCat]

Burned spark plug wires or crossed wires is the first thing you should check when this sort of stuff happens. If you cross wires the engine will probably idle rough and spit and sputter at higher RPM. If they are burnt you will probably hear a popping sound and lose considerable power when you get on it... along with a rough idle. My guess is burned wires which you can get for like $20-$30 at Autozone.

[Y2KSierra]

Originally posted by ChillPhatCat
Burned spark plug wires or crossed wires is the first thing you should check when this sort of stuff happens. If you cross wires the engine will probably idle rough and spit and sputter at higher RPM. If they are burnt you will probably hear a popping sound and lose considerable power when you get on it... along with a rough idle. My guess is burned wires which you can get for like $20-$30 at Autozone.


You are right, that is exactly what it was. It also had to have a new cat since mine was so stopped up it was causing the whole exhaust system to shake :o It got a full tuneup (plugs, wires, fuel filter, air cleaner, etc.) and the new cat and runs great now, more power than I remember it having in a very long time...for a 3.4 thats saying a lot!

[Whitey]

glad you got it all worked out :cool: