Hi there,
I’m struggling with my 02' M54B22 E46 320i (125kW) Touring, hence searching for lovely E46 community advice.
Problem description
Basically in all RPM spectre the engine is not getting the “homogenous” power. It feels like it’s not running on all 6 cylinders even though they are all firing. There’s no misfire nor MIL. When I scan the DME there’s no code, it’s crystal clear. But when you rev the engine till the red-line, it can throw random misfire (mainly cylinder 5 and/or 6 but also combination of cylinders), clean the codes and drive normally means no code; pushing to the red line means misfire/MIL.
Suspects:
Vacuum leak
First and foremost, we have replaced all the vacuum lines, including the one getting from the secondary air pump/valve thru the non-return valve to the intake manifold. The one getting to the F connector on rubber boot. Checked all the rubber boots/tubes - no crack, no leak. DISA got “upgraded”, i.e. o-ring. Idle control valve cleaned. Smoke test passed, found no leaks.
Bad CCV
In order to exclude this famous issue, CCV was replaced by original BMW (including all hoses/tubes) as well as oil cap and valve cover gasket (all original BMW).
Fuel supply
Nope, the fuel pump replaced by brand new one, including fuel filter (and hoses) MANN. Also, the fuel cap replaced by brand new one (original) as the o-ring/seal was cracked and it may have caused issues.
Camshaft sensors
Yes, that might be a problem, long crank, random stalls, missing performance etc. Both intake and exhaust camshaft sensors replaced. Still the same engine behaviour.
Engine
So, here we are. What if the engine itself has passed its lifetime? We have tried to replace spark plugs (tried both BOSCH FGR7DQP+ as well as NGK BKR6EQUP); tried to replace original BREMI coils by the NGK U5055 (still the same behaviour, hence BREMI coils put back). When the engine was idling, we’ve tried to unplug each coil (one at a time) in order to check if all cylinders are firing (yes, they are). Then tried to unplug MAF, still the same. In order to get an idea of engine health, we have performed dry compression test (get up to the engine operational temp, full throttle, unplugged fuel pump, removed fule from the rail).
If I’m not wrong, the compression ratio for the M54B22 is 10.8:1, hence 10.8 times 14.7 = 158.76 psi or 10.95 bar (that’s the min. what should pop up on gauge).
Someone said that the max. dif. between the cylinders should be ~7psi and/or ~0.5 bar. If that’s the case, then the engine is K.O? Is that just a feeling or bittersweet reality? What could be the issue? Piston rings? Valves? Head gasket? Would leak-down test be any beneficial? Any ideas/thoughts? Many thanks!
I’m struggling with my 02' M54B22 E46 320i (125kW) Touring, hence searching for lovely E46 community advice.
Problem description
Basically in all RPM spectre the engine is not getting the “homogenous” power. It feels like it’s not running on all 6 cylinders even though they are all firing. There’s no misfire nor MIL. When I scan the DME there’s no code, it’s crystal clear. But when you rev the engine till the red-line, it can throw random misfire (mainly cylinder 5 and/or 6 but also combination of cylinders), clean the codes and drive normally means no code; pushing to the red line means misfire/MIL.
Suspects:
Vacuum leak
First and foremost, we have replaced all the vacuum lines, including the one getting from the secondary air pump/valve thru the non-return valve to the intake manifold. The one getting to the F connector on rubber boot. Checked all the rubber boots/tubes - no crack, no leak. DISA got “upgraded”, i.e. o-ring. Idle control valve cleaned. Smoke test passed, found no leaks.
Bad CCV
In order to exclude this famous issue, CCV was replaced by original BMW (including all hoses/tubes) as well as oil cap and valve cover gasket (all original BMW).
Fuel supply
Nope, the fuel pump replaced by brand new one, including fuel filter (and hoses) MANN. Also, the fuel cap replaced by brand new one (original) as the o-ring/seal was cracked and it may have caused issues.
Camshaft sensors
Yes, that might be a problem, long crank, random stalls, missing performance etc. Both intake and exhaust camshaft sensors replaced. Still the same engine behaviour.
Engine
So, here we are. What if the engine itself has passed its lifetime? We have tried to replace spark plugs (tried both BOSCH FGR7DQP+ as well as NGK BKR6EQUP); tried to replace original BREMI coils by the NGK U5055 (still the same behaviour, hence BREMI coils put back). When the engine was idling, we’ve tried to unplug each coil (one at a time) in order to check if all cylinders are firing (yes, they are). Then tried to unplug MAF, still the same. In order to get an idea of engine health, we have performed dry compression test (get up to the engine operational temp, full throttle, unplugged fuel pump, removed fule from the rail).
If I’m not wrong, the compression ratio for the M54B22 is 10.8:1, hence 10.8 times 14.7 = 158.76 psi or 10.95 bar (that’s the min. what should pop up on gauge).
Code:
1. cylinder ~11.9 bar ( ~172 psi )
2. cylinder ~11.9 bar ( ~172 psi )
3. cylinder ~11.5 bar ( ~166 psi )
4. cylinder ~11.2 bar ( ~162 psi )
5. cylinder ~10.9 bar ( ~158 psi )
6. cylinder ~10.9 bar ( ~158 psi )
