Misfire Cylinder 1

[stuntflyer]

Hopefully there is a E53/M54 wizard out there that can assist me. Will list things out in point form so it's easier to follow progression of the problem.

1. 2002 E53, 444,000Km - engine was running perfectly, until I parked it for 10 days over the Thanksgiving break.

2. Tried to start after thanksgiving - no go - thought it was the starter or battery so replaced starter and batt was fine, but no start. This issue turned out to be no compression due apparently to hydraulic lifters losing pressure from sitting so long (?). Ended up getting it to start by just cranking it for like 90 secs till compression returned. It seemed to run fine after that.

3. Drove it for about 130 km - all good, until I got on freeway and accelerated up to speed - moments later it started running rough and I got a "misfire cyc 1 with fuel shutoff" error code.

4. Installed new plugs, swapped Cyc1 and Cyc2 coil packs to see if issue moved. Started fine but again under heavy load, misfire Cyc1 returns. Swapped out Cyc1 injector. Verified all elec connections to injectors are solid. No change, same thing on next test drive. The Cyc1 injector does indeed appear to shutoff when the issue occurs (cannot hear it firing/clicking via stethoscope/screwdriver), so maybe the ECU is shutting it down? Question is why.

5. Exhaust is fumy (been that way for a few years) largely because either downstream O2s are bad (not likely) or the aftermarket Cat is crap and probably failed after 6 mo (more likely). Not sure if the fumy exhaust could lead to current issue with misfire Cyc1, but aware of that issue and will look at new O2s once I slay this misfiring dragon.

6. Further background info - When I had the plenum off to change out the starter, I replaced the crankshaft sensor (put new one in since it was accessible with starter out), cleaned the injectors, CCV system is less than year old (inspected all hoses associated with it - all good), inspected/replaced any bad vac hoses, DISA, ISV, MAF, throttle body all in good working order.

Anyone have any ideas? Thanks in advance.

[docnabimmer]

FUEL AIR SPARK these are the 3 things i would make sure are working well...if plugs are new, coils are new, injectors working then I would look at the Fuel Pump? you are at a mileage where most Fuel Pump fail.
I ask you to check out E46fanatics and some important links under GENERAl Info especially the section diagnosing Fuel trim misfires etc etc etc....M54 problems tend to extend to ALL the platforms that use these engines...
FYI_ I had just went thru a single cylinder misfire that turned out to be a soft failing 165k mile original BMW fuel pump.

All is well now post replacement.

[80stech]

Do a compression test. The DME will cut out a cylinder that isn't performing properly for emissions reasons. Resetting adaptations or I think just clearing the codes will start the injector up again for a time.

[stuntflyer]

Originally Posted by docnabimmer

FUEL AIR SPARK these are the 3 things i would make sure are working well...if plugs are new, coils are new, injectors working then I would look at the Fuel Pump? you are at a mileage where most Fuel Pump fail.
I ask you to check out E46fanatics and some important links under GENERAl Info especially the section diagnosing Fuel trim misfires etc etc etc....M54 problems tend to extend to ALL the platforms that use these engines...
FYI_ I had just went thru a single cylinder misfire that turned out to be a soft failing 165k mile original BMW fuel pump.

All is well now post replacement.

Thanks for responding.

Fuel pump is not that old, and one of the first things I checked when the previous hard start/no start problem occurred was the fuel pressure - was up above 50 psi. Will check the links you reference. I will also check the fuel pressure again.

A bit more on the issue. If I reset the error codes the rough running and misfire immediately goes away, so clearly, whatever this is, it would appear that the ECU is turning off the injector feeding Cyc1.

Engine also runs fine if I turn it off and back on, and it idles perfectly. It is ONLY when I throw the throttle down and get the RPM above 3700 RPM that the shutdown of fuel to Injector 1 seems to occur. Now, more I think about this, that could be fuel pressure related, or fuel constriction related since demand for the fuel increases, but why only Cyc1 being affected? Cyc 1 IS however the Cylinder at the end of the fuel rail but cannot imagine that has a bearing on the problem. The quest continues.

[stuntflyer]

Originally Posted by 80stech

Do a compression test. The DME will cut out a cylinder that isn't performing properly for emissions reasons. Resetting adaptations or I think just clearing the codes will start the injector up again for a time.

Yup - correct - when I clear code the DME turns that injector back on immediately. Will look at compression.

[stuntflyer]

Checked the fuel pressure this morning on start, idle, revving the engine above 3500 RPM, and then took it for a test drive to produce the rough running problem (which only happens when the engine is under load - I cannot produce the problem by just revving the engine while parked). Once I was able to generate the problem where Inj 1 is shutdown by the ECU, I checked fuel pressure again. In all scenarios described above, fuel pressure sits at 50 psi, so, I do not think my issue is fuel pump, or fuel filter related. As mentioned both fuel pump and filter are not that old.

One thing I DID note using my Torque app; while the rough running/injector 1 shutoff occurs, the voltages from all O2 sensors is 0 (i.e no up/down oscillating the way they do normally), so whatever is going on, it appears the ECU not only turns off injector 1, but the feedback loop from the O2 sensors is also disabled by the ECU (?). When I erase the ODB codes the injector is turned back on by the ECU, the O2 sensors are also back online. I am curious to know which came first, the injector shutting down, or the sensors being turned off (assuming there is some relevance between those two elements).

Compression test is next in the queue.....

[stuntflyer]

And here are the compression test results:


CY1 CY2 CY3 CY4 CY5 CY6
PSI PSI PSI PSI PSI PSI
170 170 170 180 170 170

Sooo, does not look like my issue is necessarily a compression problem. Took it for another test and every time, and soon as I load up the engine (accelerate with revs above 3800 RPM), it shudders a bit, looses power, and then that injector is turned off. Wonder if the Cyc 1 exhaust port is clogged up with carbon or something?

Next step is to look at replacing the O2 sensors but, I doubt that is my issue, since they are not THAT old.

[80stech]

It's not really clear on your post but you need to 'monitor' the fuel pressure under load when the problem happens to rule that out. Spark is the next most likely thing, switching coils doesn't always rule out the coils or a spark problem. A weak cylinder, for whatever reason, usually needs more spark. Maybe try reducing the plug gap and see what that does.

[c-bass]

Is the cyl 1 misfire the only code you get?

What are you using to scan for codes? Some apps like torque won't pull all the codes compared to INPA/ISTA

[Effduration]

I think you did something when you pulled the intake..You should go over your work and consider pulling the intake again.

How did you deal with fuel rail on the orig intake pull? Did you unclip the long elec harness at each injector or did you pull rail and harness together.. you might pull elec connector and see if pins are bent and/or if it is fully seated at injector 1..

Any chance the intake gasket is folded over at the front? Did you replace the gasket?