Low vacuum and the ignition timing advance is only 2 degrees, is that normal for that engine?? How much does it advance at higher rpms like 2000 and total advance??
I read somewhere that the advance at idle should be about 13-15 degrees advanced.. That could be totally wrong, but worth checking into…
Thanks for the input. I will look into it.
Found this:
I took some live data today and to my surprise there’s a huge difference in timing on both my M52 and M54 engines at idle.
Here they are:
M54 = 1.5–>2.0 degree
M52 = 16–>17.0 degree
I don’t know if that’s how they are. I’m trying to find out what’s causing my M52 engine to knock when it’s cold, and maybe this is the culprit?.
What do you guys think?
Removed…please disregard 10 characters
Has either one or both had the timing chain messed with??
What is the vacuum on the M52 engine??
On a hot rod engine a camshafts LSA (lobe separation angle) greatly affects engine vacuum, a tight LSA gives it low vacuum and a lumpy idle, whereas a loose LSA gives it a smoother idle and higher vacuum, I am wondering if your camshafts are out of sink, like they are rotated inward towards each other somehow?? Just thinking out loud and not really thought it through… lol
Did they change at higher rpms?? the number should go up as the rpms are raised off idle up to the max point or total advance… Octane can/will affect this…
Googles AI Overview offers this:
“For a BMW M54 engine, the ignition advance at idle is typically within a range of +5 to -5 degrees, dynamically adjusted by the engine control unit (DME) to maintain a stable idle and meet emission regulations.”
So the value seen in the datastream is within this range, but AI does not always get it right.
Typically that is a +/- of 5 degrees of a set value such as set the timing to 10* BTDC +/- 5 degrees, or set the timing to 8* +/- 5* or whatever, some vehicles will be 8* BTDC + or - 2* to be with in specs, but I don’t know what the BMW specs are..
Of course if your static timing is 0* TDC the the 2* BTDC would be in that +/- 5* range… Just bench racing at this point… lol
That snip section was gleaned from a post on a bimmer group from 2014. I found the same one.
One other peculiarity of this vehicle is that it vibrates, due to the misses, I suppose. However, if you turn the engine off, and start it right back up, the vibration stops and runs very smoothly. I am fairly certain this is because the computer defaults to open loop operation went first started. This happens every time, even if the engine is fully warmed up. To me this points to a bad sensor or bad sensor wiring, as the computer does not use sensors in open loop operation. This indicates that the fuel system is intact, as is the air fuel mixture system. It must be faulty input to the computer that is causing this situation. Either that or the computer itself, or that part of the computer that operates enclosed loop, is faulty.
Restarting the engine restores operation of the cylinders the computer disabled.
Review the diagnostic information for P1343, P1345, P1347, P1351 and P1353; the computer will shut off the fuel injector of cylinder(s) that are misfiring.
There is no evidence of misfiring when the engine is first started and is running in open loop. It runs smooth as silk then. When it switches to closed loop the vibration begins. As the DTC “Misfire Cylinder X with Fuel Cut-Off” occurs for all 6 cylinders, along with P0300, “Random/Multiple Cylinder Misfire Detected”, I am led to conclude that these misfires begin occurring when the computer switches to closed loop operation, and begins to rely on sensors for input to calculate air/fuel mixture and ignition timing. If I could convince the owner to leave the car with me I believe I could make more progress.