unfortunately i think that OBD fusion log is truncated because i recorded a screenshot of the P0305 code about 15 minutes after the last timestamp. lost the bluetooth connection i guess .. but maybe there are some hint of the problem in the log. fuel trims are ok, fuel status goes to 4 but i guess that is normal when cornering hard.

 

The problem was a clogged bank 2 catalytic converter. Both cats were replaced and the issue is gone.

Post Freeze Frame data.

The problem is when the converters are clogged/restricted the cylinders cannot be purged of exhaust gases which are pretty much void of oxygen.

Then when the engine attempts to draw more air into the cylinders, there is a lack of free space for the new, fresh air and fuel to enter. So strange things happen.

maybe the catalytic converter. i don't have freeze frame data. i must have cleared the code /before/ runnning the diagnostic report.

 

Just went through this with my M3. Hesitation and stumble under heavy acceleration in too high of a gear when the engine is under load. Especially when going up hill. Problem was more evident on cold mornings but got less noticeable as the engine warmed up. At high RPM's the problem almost seemed non existent. Replaced spark plugs, all ignition coils and fuel filter. Did not fix the problem. Finally read somewhere that when BMW fuel pumps begin to fail there is a hesitation issue at low RPM under load.

Replaced fuel pump. Car drives perfectly.

or maybe the fuel pump. not sure how to test that one.

 

I assume pressure is ok. Pressure apart the only way you can test a pump is whip it out and put 12 v across it. But that's not going to tell you anything if it's intermittent. Just replace the pump. What about the filter?

 

Item #2 in the link is the cap for the pressure test valve. You’ll have to remove the cabin air filter and that ridiculously large hunk of plastic that holds the filter. Then you need to remove the top, black plastic cover (item #8).

https://www.realoem.com/bmw/enUS/showparts?id=BN53-USA-07-2000-E46-BMW-330Ci&diagId=13_0900

Fuel pressure has to be at least 50psi at all engine speeds and loads. The factory fuel pump is designed to last 5000 hours so mileage isn’t a very good indicator of when to replace the pump. The only pump you want to install is one made by Siemens/VDO. Buy it at FCPEuro as it’ll come with a lifetime warranty. Also, replace the fuel filter as it has the fuel pressure regulator. Buy either a Mahle or Keyser filter.

 

thanks.. for the fuel pump (16146766942) i guess you are right to recommend siemens/vdo ($139, germany) over the bosch ($163, china).

 

My personal experience was that my fuel filter was causing my car to lean out and to miss periodically for a few months, then one day it wouldn***8217;t start at all.

fuel filter as the cause of periodic misfire .. so hopefully i am on the right track with replacing the filter and pump first. no lean codes in my case.

 

Hi, i tell you one story :
Wife,s e83 m54b30 caught a misfire on cylinder 6. She is driving real slowly and could not notice this. Once i needed that car and vent for solving some business. As soon as i pushed accelerator it caught misfire cyl.6 and lost power. I tool it to my work (audi spare parts seller) :
1) relocated spark + coil several times - still cyl 6 (ofc codes vere deleated)
2) checked compression - it was ok
3) checked injectors - they were ok
4) cleaned all the **** out from pistons 2 times
5) smoke test
6) car came from usa so i capt those old spark plugs and put them back
wow problems was solved
after 2-3 weeks it caught a misfire cyl 1 but that was easy to detect coz coil was dead - even child could do it.
To say the truth i don't remember where i placed that cyl 6 coil but i'm 99% sure it was the coil that gave me headache back in a days. I was in a harry so got a used one for 25 lari - 7 dollars. Those parts are very close to my hose.
6 months passed everything is ok.

 

I had similar issue. Acceleration in 3rd right around 3500-4000 rpm car would cut out CEL and ABS DSC lights on and car would close to die. Turn off key restart engine and it would be fine.

I tried plugs, coils; fuel filter, etc.

Exhaust pressure test!! Failed.

Answer: New CATS.

 

thanks.. sounds like ryan in that thread i quoted above. but truly i am scared to look up the cost of new catalytic converters. a refresh of the fuel delivery system is much cheaper.

 

fuel injection hose

previously the misfire was happening on cylinder #4. i swapped the coil from #4 with #1. then cylinder #5 misfire on two different occasions, both with hard acceleration on the highway. so i guess i won't bother swapping coil #5 with #2. if it's happening on different cylinders then not a coil/plug problem, right?

Be sure to o grab a foot or so of fuel injection line to replace out the old line at the filter.

Yes, and make sure its actual fuel injection hose, not the cheap (low pressure) regular fuel hose. 8mm diameter or 5/16ths if you get the Prestone FI hose (#FJ0516) from OReilly/Autozone.

You also need to replace a total of 7 hose clamps, six at the fuel filter and one at the fuel pump itself. Edit: And also several inches of regular vacuum hose to go from the pressure regulator on the filter to the hard "vacuum" line, which goes up to "f" connector on the intake boot.

so i'm starting with a new mahle fuel filter. i get the new clamps and the new vacuum line up to the F connector, but do i need the new fuel injection hose? ** yes, easier to cut it off than to try to remove it.

 

hose clamps

1/4-5/8" clamp - hardware store

5/16 in. Seal Clamp:
https://www.napaonline.com/en/p/SERK2980
are these the right fuel hose clamps to use? not sure if they are oetiker?

SharkBite 25-Pack 1/2-in dia Stainless Steel PEX Pinch Clamp Crimp Fitting:
https://www.lowes.com/pd/SharkBite-...ite-25-Pack-1-2-in-dia-Stainless-Steel-PEX-Pinch-Clamp-Crimp-Fitting/1000182823

Oetiker Clamp 5/8" 15.7Mm:
https://www.summitracing.com/parts/rra-18-9133-9

Fuel Hose Clamp - Genuine BMW 07129952104:
https://www.fcpeuro.com/products/bmw-fuel-hose-clamp-07129952104

 

fuel filter DIY

https://www.youtube.com/watch?v=0DUR484OmjI

good tip to let pressure out of the schrader valve, but at 10:34 i don't think i would reuse that rusted cover.

https://www.youtube.com/watch?v=8t-6raUI8vs

nice idea at 5:00 cut a hole in the hose to drain the fuel.

http://bimmerinfo.com/diy/fuel-filter/
PDF copy in case host goes down - https://www.e46fanatics.com/pdf/E46-BMW-DIY-Fuel-Filter-Change.pdf

even better idea to remove the fuse #54 and turn over the car to remove gas from the lines.

 

another 330 owner told me today how he solved the misfire by replacing the knock sensor. possible that a faulty knock sensor (13627568422) could be causing these misfires?

*can i just unplug the knock sensors to test this theory? *wondering how a false knock signal would be interpreted.

 

I would guess no. Experiencing knock, the DME would retard timing and this would be clearly visible in logs or real time. A knock sensor fault (disconnecting them) will throw a code and probably retarded timing for safe engine operation.

 

Your symptoms sound similar to a problem I had that turned out to be the rear catalytic convertor. Error was something along the line of "Cylinder 4 misfire with fuel cutoff". Cut the ignition; restart; misfire would be gone until the next episode, which would always occur under heavy load or hard acceleration. Suggest you test the back pressure of both catalysts.

 

thanks .. same as golf5367 and ryanr1299 above.

https://www.amazon.com/OEMTOOLS-27263-Exhaust-Pressure-Tester/dp/B01FIJZPXY/



how about this oemtools back pressure tester?

i just need to figure out how to test the back pressure. i'm supposed to replace one of the oxygen sensors with this back pressure tester and it should be 0 bar? otherwise my cats are bad and/or my exhaust is blocked?

 

bmw scanner

DME scan shows misfires during start up and something wrong with DISA. next time i get the P0304/P0305 cylinder 4/5 misfire i will run both the obd fusion diagnostic and DME scan to see if it gives any hints.

 

I was also going to suggest checking your ignition harness.

Is the misfire during startup or high load? Did you check freeze frames before? With all those short to ground faults, is this DME related?

 

misfire under load is the problem for a couple of months now, but the cold start has also been rough. the fact that the misfires under load have always been bank2 cylinders 4,5,6 tells me that the previous guys here are dead right about the bank2 catalytic converter.

every time it happens i***8217;m in a rush to get somewhere and clear the P030x code before running a proper diagnostic. next time i will do better.

i***8217;m not sure what those short to ground faults mean. a new harness might be required because i don***8217;t think my m54 harness will mount properly on the m56 valve cover.

 

so today i tested the fuel pressure at the local independent. normal 52 psi. also it looks like the fuel filter was replaced by the previous owner at 100k miles. so doesn't seem to be any fuel delivery issue.

mechanic says that cat problems are not so subtle as an occasional misfire. he wants to measure the before/after cat temperature instead of measuring exhaust back pressure. he is worried about the oxygen sensors not coming out without difficulty.. umm ok fine .. i will just go and buy the back pressure gauge then.

has to be a bank2 problem because the misfires are always one of cylinders 4,5,6 at acceleration load. what other culprits are specific to bank2? oxygen sensor itself? i'm hoping the misfire will happen again soon so i can capture the freeze frame this time.

 

Definitely test the pressure. The O2 sensors came out easy.

I wasted alot of $$$ replacing other stuff and did not want to admit it could be the CAT's...

Nothing worked, the pressure test on the exhaust proved it was the CAT's. My symptoms were consistent when under acceleration in 3rd 3k-4k it would cut out and misfire. When I summarized this the trusted folks on this forum said... its probably the CAT's.

Once they were replaced the car drive like it did when it was new. Did not realize how poor it was running until I had them (BOTH) replaced.

I got them from DEC Cats and I am never happier.

 

Once they were replaced the car drive like it did when it was new. Did not realize how poor it was running until I had them (BOTH) replaced.

I got them from DEC Cats and I am never happier.

http://www.deccats.com/catalog/ .. nice catalog, i like how they have removed california and new york as foreign countries. but i'm not finding anything for my car in their catalog.

assuming i need to replace the cats .. and that's a pretty big assumption .. should i go with catless exhaust manifold and a detached "cat back" setup like bimmerbrakes?

that setup is cheaper and better than replacing the OE exhaust manifolds (18407514504, 18407514505)? sorry if i am using the wrong the wrong terminology here.

 

I got BMW1404R and BMW1404F which are the integrated manifolds with cat's...

Catless will throw codes and need some type of flash to avoid that, i just bought them both thru a reseller since DEC does not sell direct.

Replacement requires the engine to be tilted to remove the manifolds, i had someone do it b/c I was too nervous about removing the motor mounts and tilting the engine.

 

The 05 330xi I bought 1.5 yrs ago with 154k miles has been a different story. Countless $ spent because I had zero history on it and daily drive it to the tune of 20k+/year. Currently, it is in bas.ard mode giving me misfire under heavy load.

yeah i am familiar with that mode. i guess i am lucky i have partial history, but really would like to know what was replaced in the first ten years. i would bet that bmw sterling did most of the work .. not sure if they would disclose without the owners permission.

 

I believe dealers will disclose maintenance history of vehicles they have serviced, but charge a fee.

This is a good thread. I've been holding off starting my own for the last week or so. I'm experiencing nearly identical symptoms, except my code has been limited to P0302 Cylinder 2 Misfire pending. I've done coil swaps, but the code stays w the #2 cylinder.

The gremlin shows its face under the same circumstances listed above by others - moderate to heavy load climbing a hill. It's happened a few times on the highway as well as state roads. The first few times the code went away and car ran fine all on it's own after either stopping at a light or going down hills. The last few times I had the code reader hooked up. Each time I reset the code and car ran fine immediately.

Additionally, when it sh.ts the bed both Fuel System Status go from CL to OL- Fault. LTFTs are averaging 6-7% bank 1 and 5-6% bank 2.

I replaced both the fuel pump and filter in the last 20k miles preventively, VDO and Mahle respectively.

I ordered spark (Bosch) plugs today and will install upon arrival since I dont know how old they are - this is assuming they come out (see another thread I started last night). Also have new precat O2 sensors enroute - they do not look new at all based on the corrosion. After reading this thread I'll probably buy a back pressure also to see if my cat(s) are spent. Awesome!

That's enough typing.[emoji15]

Thanks @wfx32 for cluing me into this thread.

Sent from my SM-G950U using Tapatalk

 

the problem looks to be the cylinder head gasket. coolant getting into cylinders 5 and 6. not sure how feasible this is as a DIY.

 

Always nice to find the culprit so a fix can be applied. However, a head gasket isn't exactly at the top of the list simple diys.

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How much coolant is it using that it wasn't noticed?

 

very little coolant burn. misfire has been a problem for months. sweet smell and the white puff of exhaust started in the last week or so.

only when the radiator developed a leak did we pressure test the system. and boroscope showed coolant in cylinders 5&6.

i’ve got another mechanic verifying. really glad i waited on the cooling system refresh. need to solve this first.

 

ok so i am finally ready to tackle this head gasket issue. i know folks say to leave this repair to the professionals but i think this should be doable. so some questions:

are the special tools to lock the timing of the engine absolutely required? where is the best place to get these - pelicanparts (https://www.pelicanparts.com/BMW/te...s-E46/114-ENGINE-Head_Gasket_Replacement/114-ENGINE-Head_Gasket_Replacement.htm)?

the second mechanic said i should prepare to deck the head and time-sert the head bolt holes. but i am hoping all that is not necessary. can i retorque the head bolts to verify the theads in the head are not stripped (https://www.bimmerforums.com/forum/showthread.php?1541508-headgasket-diy&p=20504072#post20504072)? and how to verify the head is not warped? just take it out and put a straight edge on it?