Troush

My '04 545i, manual has started acting up on me. When I take off in first gear I feel a hiccup and I feel the same kind of hiccup but more apparent under hard accelaration. The car smooths out when cruising especially over 3,000 RPM but does anyone have any thoughts as to what could be causing this? Fuel pump? Throttle body? Crushed Catalytic converter?

Thanks in advance!
Tobey

richark1

When's the last time you changed the air filter? Had the same symptoms. Dumped a bottle of Techron fuel system cleaner to see if that would help, but couldn't really tell much of a difference from before and after. Replaced the cabin filters, and checked the air filter to see if that needed to be replaced. Found all sorts of crud in the housing, as well as a beat-up filter that was sunk-in and collapsed. Cleaned the housing and repositioned the filter and now car runs much smoother. Can't remember the last time it was replaced, so probably long overdue

Troush

Thanks! I have a K&N filter and checked last night...I vacuumed it out but need to get clean it and oil it tonight with the K&N product. I will keep everyone posted.

Thanks!

or_550i

Most likely the 'learning' from the transmission. Reset it:
insert the key, push the start button without pushing the brakes, then hold the gas pedal down.
After thirty seconds push the brakes and start the car

pauliehcfr

I dont know of any way to reset a manual transmission, but ok. the hiccup can be caused by many things. first start by reading out the fault memory. there could be something stored in there that will lead you in the right direction. bad gas can do this also, dont buy cheap unbranded gasoline as it tends to contain excessive moisture. did you recently fuel up?

richark1

I just ordered a K&N. Does it come pre-oiled or do I need to oil it before putting it in?

or_550i

Ah. I read right over ... manual...

Troush

The symptoms did start after a fill up but definitely have gotten worse. I have sense filled it up twice and added Techron fuel system cleaner last night. It definitely seems to be getting better! However the Service Engine Soon light is on and the code said Emissions! I wonder if I have somehow damaged my CAT in one of these god for saken pot holes.

Any additional thoughts? I am taking it in to the dealer Monday unless I figure it out before then.

Thanks!
Tobey

Troush

PS When I have bought a new K&N, it did not have to be oiled...only after I clean them.

pauliehcfr

you may have gotten moisture in there. run a bottle of drygas in the tank, should help burn off the moisture. get the check engine light evaluated as that might have something to do also. as far as k&n filters, don't oil them too much as the oily residue will build up on the mass air flow sensor.