Okay, so I have read a lot of threads on misfires and lean codes at idle, but I figured since this is more track day related it's best posted here.
Long story short I picked up an unfinished project car; 2003 325i M54 for a drift build.
Its needed a few things but overall it was in good condition for 160,000 miles
It purrs like a kitten cold but starts to misfire when it gets hot, (like drift abuse hot) I have found this out the hard way with a drift day this weekend.
So i run it hard; car loses power and shakes, get back scan it; camshaft sensors, and multiple cylinder misfires with fuel cutoff.
So, we dug into it... compression test showed 180-195 on the cylinders. No oil in the coolant. Smoke testing showed leaks so replaced intake boots, intake manifold caps, inspected underneath, made sure smoke was coming out of the oil cap, etc. No further leaks could be found.
Ran it again; multiple cylinder misfires with fuel cutoff.
Fuel pressure tested. 44 psi key on, dropped to 40 when off. Replaced Fuel filter, 47 psi key on. Holds 45 key off after 10 minutes. Fuel pump has 45-50psi fluctuating while redlined even. Everything fuel related looks okay.
Inspected DISA, no damage but it doesnt hold the flap when my thumb covers the hole, it just opened completely.
Replaced DISA, (this one just slowly turns with the thumb test. I'm not sure what proper spec is, ive heard both hold or slowly dropping is okay to be honest)
Car idles with the misfire, disconnecting coil #3 #4 don't change anything, swap coils, problem fixed, run it again, #3 #4 misfire is back
Clean the MAF, take electrical cleaner and clean off all the connections we can find (Coils, DISA, MAF, the one on top of the intake, VANOS solenoid up front)
Run it again, misfire with fuel cutoff and now crankshaft sensor code 0336. (this is where I get worried)
Bring it back to camp, go to restart.... no crank. Lights on the dash, but no crank. Under the car you hear a click, no crank. (EML light turns off after 2 seconds of a no crank)
Let it cool down for 5 mins: no crank, try again, fires up. Has a misfire immediately.
Try to find codes, no codes present. Look for pending codes, shows multiple misfire w/fuel cutoffs & misfire during start (misfires during start is new one)
Tried clearing codes, misfire was still there. For whatever reason clearing codes couldn't get the car to idle right. Maybe the Crankshaft sensor is just cooked now and its causing all of this? Fuel system in the past has been status 8 and open loop on freeze frame data.
Short term fuels have been 20+% and sometimes they show 0% in freeze frame data.
Few things to note, (maybe this is causing my problem)
VCG has a leak (more present in back by #4 5 6)
Fuel level gauge on the dash doesn't work. (rests far left at E)
Coolant temp gauge is weird. Dash reads a little hot but my manual coolant temp gauge reads 195-205, OBD reads the same as my manual gause, 195-205.
My thought is something changes when the car heats up and is causing a vacuum leak.
I don't think it's fuel
I don't think it's plugs or coils
I think it may be major electrical (power, ground, wiring)
I think it may be an intake manifold that's cracked.
Few questions:
Could a bad Pre-Cat O2 sensor cause this ?
Is a vanos seal failing when hot?
Can a bad crank sensor cause all of these fuel cutoffs AND a no crank?
Does smoke testing it once its hot help or hurt a diagnosis? I was told you only smoke test cold.
Could it be the secondary air pump failing and causing the car to lean out?
Thank you everyone
Member
Originally Posted by NorthWestM
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