Running Ruff.....! HELP!!!! PLS

[saza]

Hi everyone, i need some help. I have a BMW 540I. The problem that i have been having is that the car is running really ruff. I have done a tune up and checked all filter and plugs. But it still runs ruff and is waisting a tone of gas. A full take use to take me 2 weeks well the way i drive, but now, it like a full tank for a week. Dose anyone have any suggestions??? Pls need Help GAS IS KILLING ME LOL :

[///Matt]

what year is it?

[97alpineM3]

Year... mileage... mods?

Sounds like either bad O2 sensors... but they would have been seen in the tune up.

Good Luck,

Les

[sp0rky]

Generall o2 sensors make a difference, but not THAT bad.

My guess would be that you have a moderate to severe vacuum leak somewhere. Possibly even a clogged catalytic converter (USUALLY wont cause rough running, but does eat gas, lack power, etc)

[saza]

Hey guys. sorry forgot the sats. Its a 1997 540I i have about 140km on it. My mech cant find anything, but i'm starting to think that he smoking to much crack lol starting not to trust him. When the car is on it just sounds ruff like you can hear the engine. it use to not be like that.

[94ISCPE]

Mass Airflow Meter/Sensor can cause this exact problem, and may or may not always cause a check engine light. Running super rich can quickly cause problems with the O2 sensors as well, so you may wish to fix ASAP.

[saza]

Well that's funny that you say that cuz, cuz ever since the car started to run ruff the check engine light come on once in a while.

[94ISCPE]

It's really an easy fix, part can be a little pricey, look around online. If you do any of your own work this will be super simple.

[saza]

Hi there, sorry to ask again but what are the parts that i should be looking for. I have a friend that will do the work for free but need to know the parts, Sorry as you can see i'm new to all this. But thanks so much for all your help.

[94ISCPE]

The part name sometimes varies slightly from car to car, but what you are looking for is commonly reffered to as either a Mass Airflow Meter or Mass Airflow Sensor (same thing). It is the part just rear of the air filter that has a plug going to it, part of the intake tube. It measures air volume coming through the intake so that the computer knows how much fuel is required (this is a very basic explaination). A good friend had the same problem on his X5, which has the same engine as your 540. I am pretty sure you can get the part at any auto part supplier.

[///Matt]

Find someone who has, or buy, an OBDII scanner...it'll show what is causing the check engine light which will narrow down the problem pretty damn quickly.

[94ISCPE]

Both Autozone and Advanced will let you use an OBD II scanner for free. This is usually a good idea, although scanners are not always right (meaning various electrical/sensor issues can cause multiple codes to trigger).

[saza]

I C, Thanks o lot guy you dont know how much this helps. I just got my mbw from the dealer ship and as of yesterday the are charging 160.00cad for 1 hour of laboure. 94iscpe thanks for the info on the part. I have found the part over here for $250.00 cad. Everyone else has it for 600.00 to 800.00, but i will ask my friend to use the OBD II scanner and check. thanks again for all the information.

[saza]

Hey sporky, thanks for the info but the car has 2 brand new catalytic converter and 4 new O2 sensors, but still having this problem.

[sp0rky]

Ohh good, one thing is surely eliminated then.
Like I said, maybe check for vac. leaks, and as everyone else said, maf, etc.
I didn't read all the latest posts, but maybe have all the ignition coils tested? When one or two of those go bad, the whole thing gets a little shakey.