Hello, I've got a problem with my E46 320I on 53plate.. with 147k on the clock.

Ive had it in an Indy for 5days! and they still cant tell me what the problem is and sounds like his cluching at straws! at my expense...

When the car is cold its runs fine, well it does seem to have a slight flat spot around 2000/2500rpm, it will pause for a sec or 2 before the power starts to kick in, but when its reached temp (halfway on the gauge) it gives a slight jolt and loses all power, the engine just seems to rev and takes forever to build up any speed.

I had these codes show up:

(241) F1 misfire, cylinder 4

(242) F2 misfire, cylinder 5

(243) F3 misfire, cylinder 6

(234) EA catalytic converter efficiency, bank 2

(233) E9 catalytic converter efficiency, bank 1

I also have a thermal oil level sensor fault

eml is on

When this power loss happens it shuts off cylinder 5, and once or twice its been cylinder 4 but most of the time its 5, ive changed the plugs and swapped the coils around and still the same cylinder/coil stops working. I shut off the car give a minute or 2 restart and its fine again for a bit.

The indy wants me to pay over £2000 to strip the engine down and maybe replace some parts to do with the cylinder so he can see whats going on and even then he tells me it might not cure the problem! and I could be looking at £000's to repair.

Which is all well and good but what does'nt sit right with me is if I have such a major fault like he said i have why does the car run fine cold?

I got him to test the cooling system and he said all of that was working and in good shape coolant temp does'nt go above 88, I got him to check the fuel system as he said it might be starved of fuel and again all of that was fine! It does and always has burnt quite alot of oil, about 1ltr every 100/200 miles with no leaks and its not coming out the back. it does smoke abit on startup (white/blue) and when you push over 3500rpm and you can smell the oil burning whist its running, thou no oil is getting to the plugs or water. I also get the coolant light come on at random times, but ive not lost any and its always full.

The thoughts I have is maybe a faulty/blocked cat? sensor? ecu? doing this....

any thoughts are most welcome!!!

just an update, ive been checking the cat as i think this is where the problem lies.

The front cat is red hot after a mile or 2 yet the back from the engine to the tail pipe is cold!, after about 10 miles the back is still only warm to the touch where is front will take your skin off!

almost blocked cat?

do you think that would cause the above to happen, and am i doing any damage running it so i can try and work out whats wrong?

It could be the Valvetronic control unit got a bit mental and sending out loads of codes i doubt its the cat they are meant to get hot quick. get your car back from the indy find a second hand unit on ebay for about £70 and try that, easy job locate and unplug. if dont work sell it on and think again. i will find pic for you. Dont let them strip unless they are bmw specialist its a complex engine if you dont specialise in them .good luck