St St St studdering!!!

Ok maybe you remember my previous posting about a =cold start issue=
which I never got resolved ,cuz not even the stealer could tell me what was wrong....I've been since then driving around with the Crank posistion sensor unplugged...the car takes about 2 to 3 seconds and then starts right up no matter how cold it gets...
Anyways my exaust was getting louder and louder (kinda sounded cool at first like an aston martin..) but then it was way too much so I just dished out the cash for a new muffler ....then the mech tells me i have to change both of them....bimmer...I mean bummer....So, I just spent 600 dollars on 2 mufflers and threw in an oil change.The runs like butter for 2 days but now Its stammering when i try to push it,...Kinda feels like its being clogged dpwn or something...
So my question is..is it possible I got a bad muffler....It also smells burnt when I get out of the car,so I got under the car and the center muffler is getting really hot...anyways any advice would be apreceated...
as for the cold start thing..I still have the CPS unplugged...I found a used ecu should be getting it in soon ...

Thanks and happy new years..........

my car....1994 bmw 520i (m50b20)

running it without the CPS can cause all sorts of problems, you may have melted your cats?

yes I had my suspisions about that ..but believe it or not the dealer was the one that suggested I leave it unplugged after they changed the camshaft AND the crank posion sensor twice the mech suggested I leave it unpligged...I asked him if there was a danger which is why I wanted it fixed in the first place but he said no....but those guys are real idiots they actualy gave me the car back said it was fixed and I asked them if they had waited till it cooled complety down before checking it ,,,which they hadn't; so i was still in the same boat...
Gonna have to have that cat checked I guess .... damn that's an exensive one from what I hear.... between christmas the new baby maybe I just have no business drivin a bimmer ....might be better to look into trading it ....
but if they can't find the original problem and I change the cat it will just break again no?

you can and will fix the original problem!

you may just need to take it to someone who is smarter than a dealer tech, like a computer hardware enginner who also is very into cars.....

at least then they could do some old fashioned diagnosis instead of letting some computer try to figure it out for them.

Do you know if they checked fuel quality and pressure? I dont know much about the 520 as Ive never seen one here in states but I assume its an M50 based engine?
-If theyve checked all the sensors I would definitely look at the plugs and coil boots. The valve cover can leak oil into the galleys and cause the coils to short, or just cause a bad connection to the spark plug. Im not sure what all you have already checked but that would be an easy next place to look if you havent. Hope this helps.

-Ben

Yeah that was one of the first things my mech did was change the valve cover gasket and we got 1 new coil and switched each 1 out to see if this was the problem we also put new plugs and boots in (tried first the factory bosch and now have ngk iridium plugz...(I do actualy feel more power out of the car with these and use less less gass also my ilde is really smooth with these...or was untill a few days ago)...I have also changed the fuel pump about a year ago now
and he said he had checked the injectors...
it is an m50b20 motor
I just got a new (used computer in the mail) so gonna swithch that out over the weekend ,,,but i have a feeling i have already ruined my cat as its getting hotter each time I drive and smells worse as well. Hopfuly the mech has time on monday i am trying to drive as little as possible so as not to get stuck .. ;(
oh I don't know if it means anything but it runs smooth now at first start and gets bad once it's warmed up (but will never start with the cps plugged in)
thanks for the help....