E34 Rough and Powerless

[sam726 29]

Hi guys

I have a 1990 BMW 535is, last night when i was driving the car it suddenly started running rough and sounds like it has a miss or something. It has very little power and when you get to the medium to higher rev range it sounds a bit like a boxer engine or something its low and loud. I took it to be diagnostic scanned and the results said the O2 sensor off the exhaust.

I was just wanting to check with the bimmersporter's whether they have heard of such a problem and whether you think that sensor is likely to be causing the problem. Another thing to note is that it doesnt seem too much rougher when you are idling but when it drives the problem is extremely obvious?

Thanks for any help,

[*Glenn* 854]

The O2 sensor will not be the fault. It will be registering a fault code because it is trying to operate outside it's working scale. I would hazard a guess that a bad air leak is causing your problem or a blocked cat

[sam726 29]

Thanks, i just changed the spark plugs too, the 2nd cylinder plug was very black and sooty moreover the rest. Wondering whether there could be an issue there.

[sam726 29]

Also, my car has no catalytic converter so that cant be the issue, will probably take it into the mechanics on monday as anything past spark plugs and things is past what i can work on.

[BM WORLD 1264]

what condition is the dizzy cap and rotor??? .

fuel pump on the way out ??

fuel filter blocked??

[sam726 29]

After driving it a bit more i started to realise that this wasn't going to be a minor problem. Took it to my mechanic and he confirmed what i had thought which is that hes almost certain it has dropped a valve or something along those lines so it looks like its time for the engine to be taken apart which is a bit of a bugger. May want to look at options of rebuilding too.