5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
my BMW is misfiring between 2K and 3k rpm. it used to be really bad until I replace the valve cover gasket, spark plug well grommets, spark plugs( gapped properly). I think that it is the valves, they need to be properly adjusted. There is a tap, witch is giving me that idea. the engine is also hunting but only by a 50-100 rpm. this is enough to push the car forward a few inches when I am sitting at stop lights. I just am wondering if my diagnosis of valve adjustment is correct.
I believe your car has an M50tu, which have hydraulic valves, basically they automatically adjust. its possible you could have oil not flowing properly in one of them. I am not sure how to go about testing them though as i haven't disassembled them before. My car has the same engine and would tick if i let it sit for a couple weeks without driving it, as long as it had oil though the tick would go away after a few miles of warming up and wouldn't come back till i let it sit again for awhile.
Honestly though i would probably check the ignition coils first, since there are six of them, make sure they are not loose, i have heard before if the get loose they can make an arching noise that ticks that probably could cause a misfire as well
I have mechanically actuated valves in my engine. when I replaced the valve cover gasket I saw the cam shaft and timing chain. this is my grocery getter, school transportation vehicle. it is on almost every day. all of the coil pack are tighten properly, I torqued them to factory spec when I last gapped the park plugs a 1000 miles ago. I am going to test the coil pack when I get the chance, but I currently am too busy.
Oh ok, cool, just out curiosity did you convert to mechanical or solid lifters, i saw a kit online and thought about it, but scrapped the idea since my car is a DD. To your first post i think it is possible that valves need adjustment especially if they haven't been done in awhile, that would definitely cause a ticking noise, unfortunately i dont know what the clearance or interval would be for this engine.
Also it might be worth checking the TPS, i dont have the bentley manual in front of me as my laptop broke that had a copy of it but just from google i found some values that might be correct:
( TPS should be 1-4kohm (continuosly varies with pushing down gas pedal) on pins 1-2 and 4kohm on pins 1-3)
I will see if can find another copy and make sure its right. Although i am not sure if a bad TPS would make that ticking noise. Also does the noise speed up with increased throttle.
What oil are you using? Too heavy an oil can cause ticking.
Another cause is the VANOS seals failing. Usually sounds like marbles rattling around, but ticking is also common. Also check for vacuum leaks. The surging sounds like the engine is getting unmetered air and cant compensate properly.
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