Entire bank1 misfires, and lower compression. 1997 BMW 5...

Q: Entire bank1 misfires, and lower compression. 1997 BMW 540

asked by on February 13, 2017

I have a 97 BMW E39 M62 non-vanos. I Recently completed timing chain guide rails replacement. After I completed, I got Blinking CEL. P0300, P0301,P0302,P0303,P0304 (random misfires) on cylinders 1,2,3, and 4. I Replaced Fuel Injectors(new), Spark Plugs(new) and swapped Coils to see if misfire followed. They did not. I then did smoke test found leak from CCV/PCV and gasket between throttle body and intake. Replace CCV/PCV and throttle body gasket. Re-did smoke test, no more leaks. Misfire still present. (No oil or coolant leaks, no engine knocks, no smoke. 248,000 miles on clock. Idle is around 500 rpm's steady. Car drives okay) I also did dry compression test. Considered wet test. The following are my dry readings. Bank1 Bank2 4-155 8-180 3-165 7-185 2-155 6-195 1-167 5-185 I did a back pressure test to check for clogged cats, 2pre cat O2 sensor hole, 0 psi for both.

Is it possible for just the bank 1 cams to be incorrectly timed? What could I be overlooking?

My car has 248000 miles.
My car has a manual transmission.

Hi there - yes, it is possible to have cam timing for one cylinder bank off after a timing chain component repair. Way too easy actually with this engine! If you did not loosen the cam sprocket to cam bolts to re-time the cams (even with the BMW timing block tools present), it’s easy to mis-align the cam. Usually you get a crankshaft/cam mistime error code, but not always. And, the engine will run relatively smoothly, although without full power, and as you have experienced, less than optimal compression on a complete cylinder. I recommend you double-check the cam timing (relative to the crankshaft) by the book, and re-time the cams (both) if needed. For assistance, I recommend a cam timing service performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, and re-time your camshafts.

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