No idea what to try next....
'92 525i, auto trans, M50, non-VANOS, 243,000+ (still usually 22-23mpg)
Experiencing a horrible miss/stumbling pattern and I just can't figure it out.
Started with an intermittent CEL back in the beginning of August. Code was O2 sensor. Noticed it had a slight miss every now and then, and mpg was dropping slightly over the next two weeks. Installed new O2 sensor. CEL has never reappeared, and no codes are present.
But the miss/stumbling has gotten absolutely horrible. I have A LOT of cash wrapped up in this already, and I'll NOT quit now.
Following is a list of what I've changed/repaired, etc.:
•Fuel pressure regulator
•Feed/return fuel hoses (at the rail)
•Two vacuum hoses from PCV
Checked and verified OK:
•Fuel pump electrical and system pressure
•Cylinder compression (all within acceptable ranges)
•All sensor electrical plugs
•All other appropriate electrical for fuel/ignition system
Vehicle starts fine, idles and drives great, until it starts to warm up.....then the idle becomes erratic and the missing starts. Driving at highway speeds (above 60mph) and it's basically smooth, even when stomping it to the floor with the resulting gear range kick-down. City driving is nothing but stumbling, sputtering, chugging....it just seems like symptoms of intermittent spark and/or fuel. If I sit in the driveway with the parking brake on, my foot on the brake, put it in drive or reverse and press on the gas, it misses so badly it shakes the whole vehicle and won't get above 2000rpm.
ANY / ALL ideas are appreciated. Thanks.