[chknlytle]

Hi fellas,

I need some help trying to figure out a misfire in cylinder 4. But first let me say all that's happened/been replaced in the last week.

Car: 2012 x3 35i xdrive build date 3/12

-Last week CEL came on for low fuel pressure and random misfire. The car was bucking and jerking, would die out a few times, and you'd instantly smell raw fuel at the exhaust after start up. We determined that the high pressure fuel pump to be the culprit and replaced it with a BMW one. A little over $1k

-After replacement, it would hesitate (but still drivable) then CEL came on for cylinder 2 misfire. Found that the injector was bad, so we replaced that.

-After replacement of the injector, car STILL missed and CEL came on for cylinder 2 misfire again. This time the spark plug was fouled, probably from driving a bit with the bad injector. So then we decided to change ALL 6 plugs.

-Still missed and decided to clean the intake valves with walnut blasting since I have access to one, and nothing.

-After replacement of all 6 plugs, car STILL missed but now just on cylinder 6. So then we decided to replace ALL of the injectors...

-And car STILL misses, throwing a code for cylinder 5 misfire

Recap: Car has brand new oem high pressure fuel pump, 6 new oem plugs, cleaned intake valves, and 6 new oem injectors. I haven't replaced the coils yet because all 6 have been replaced about 6k miles ago, and we've been swapping them out to rule out the above problems.

Does anyone have any ideas on what to look at next?

[TheCoolX3]

If I've learned anything when fiddle fucking with these cars its that new does not always mean good.

I would pull the injectors and flow test them to ensure they are good. I'd also pull the plugs again and give them a look. The condition of the plugs may help diagnose what's going on here. While you have the plugs out, a compression test may not be a bad idea. With a stuck injector, you may have gotten fuel wash. If you do not know, fuel wash will displace the oil in the cylinder and score it up to the point of bad compression. I'm skeptical of the motor being shot because the miss moves, but not a bad thing to check.

In my BMW experience, random misfires like what seems to be happening in your case are from unmetered air. That being said, I'd get a smoke machine and test for vacuum leaks and then do a boost leak test.

Also, play a game of hot potato with the ignition coils and see if the miss follows the coil.

Can you share anything else about the miss? is it all the time, is it partial, throttle dependent, etc?

[chknlytle]

Originally Posted by TheCoolX3

If I've learned anything when fiddle fucking with these cars its that new does not always mean good.

I would pull the injectors and flow test them to ensure they are good. I'd also pull the plugs again and give them a look. The condition of the plugs may help diagnose what's going on here. While you have the plugs out, a compression test may not be a bad idea. With a stuck injector, you may have gotten fuel wash. If you do not know, fuel wash will displace the oil in the cylinder and score it up to the point of bad compression. I'm skeptical of the motor being shot because the miss moves, but not a bad thing to check.

In my BMW experience, random misfires like what seems to be happening in your case are from unmetered air. That being said, I'd get a smoke machine and test for vacuum leaks and then do a boost leak test.

Also, play a game of hot potato with the ignition coils and see if the miss follows the coil.

Can you share anything else about the miss? is it all the time, is it partial, throttle dependent, etc?

Thanks for your reply.

To answer your question, the miss goes away or gets better when I clear the code. But comes back after driving a quarter mile or so. Once it starts missing, it is present under all driving conditions and at idle.

I don't have access to a smoke machine but will visually inspect the intake system.

[TwinSnailz]

Try unplug the maf sensor ( on pipe right after filter box)and drive. Although you will get a cel for unplugging it. It will put you car in closed loop mode to rule out any problem associated with sensors( maf , o2 etc). If it runs smooth then you can troubleshoot for sensor problem.

[chknlytle]

Originally Posted by TwinSnailz

Try unplug the maf sensor ( on pipe right after filter box)and drive. Although you will get a cel for unplugging it. It will put you car in closed loop mode to rule out any problem associated with sensors( maf , o2 etc). If it runs smooth then you can troubleshoot for sensor problem.

Missing was still present when unplugging maf. Going to inspect coil #5 and switch them around to isolate the problem. I’m just confused because the miss keeps jumping around. If #5 coil was good when #2 was missing, why would it be bad now, you know?

[383vett]

Originally Posted by TwinSnailz

Try unplug the maf sensor ( on pipe right after filter box)and drive. Although you will get a cel for unplugging it. It will put you car in closed loop mode to rule out any problem associated with sensors( maf , o2 etc). If it runs smooth then you can troubleshoot for sensor problem.

Actually if the maf is disconnected, the car will be in open loop.

[E90705]

Swap coil 4 for 3 and 2 for 1. And see if 4 and 2 are misfiring...I've had a new Delphi coil take a shit under 5k miles..

[evilchargerfan]

following, interested to see the outcome / resolution

[Lurcher]

How about posting the actual codes to start....

[chknlytle]

Originally Posted by Lurcher

How about posting the actual codes to start....

The only code I’m getting now is P0305

[chknlytle]

Swapped coils, still got P0305.

Swapped plugs, will go for a test drive. But just wanted to post these pics of the plugs to see if this is normal or not. There’s barely 400 miles on them.

[Marty in NY]

The plugs look sorta ok, they should be dry and light brown but they don't look bad. What do the rest look like? Go to this site, plug in your error code, select your engine and read through all the possibilities presented in the results and try to dig into it as you are doing.

https://bmwfault.codes

This is the screen that popped up for me.. .. read through the results and also click on each "View" to read what the site is recommending.

.

[TwinSnailz]

Originally Posted by chknlytle

Missing was still present when unplugging maf. Going to inspect coil #5 and switch them around to isolate the problem. I’m just confused because the miss keeps jumping around. If #5 coil was good when #2 was missing, why would it be bad now, you know?

You’re saying missing is on 2? P030-5 the 5 is pointing to cylinder 5. What brand coil do you have on now?

[chknlytle]

Originally Posted by TwinSnailz

You’re saying missing is on 2? P030-5 the 5 is pointing to cylinder 5. What brand coil do you have on now?

They are Bosch coils. And what I’m saying is that at one point it was P0302, then after changing plugs, it went to P0305, so I’d assume the coils are all good.

Update: switched plugs #5 with #1 and now getting P0301 cylinder #1 misfire. Because the plug looked foul, I will drive around a bit more and check #5 if it has become fouled. If so, will look at the fuel system (again) because all 6 injectors are new. Maybe fuel pressure sensor is bad?

[TwinSnailz]

The new injectors you swap was the same EU version?Eu5 and Eu6 injectors are non-interchangeable.

I once bought a set of BmW stamped injectors from ebay and it cause some misfire. Put my old but decent Bosch back in and trash that new set.

[najnad]

new parts dont always mean the parts are good. I had a brand new spark plug that was bad out of the box, but of course initial troubleshooting I dismissed the thought the problem could be a spark plug as they were all new. So if nothing else is obviously wrong, get the plugs/coils/injectors tested to see if one of them has a defect, even if new.

[383vett]

Originally Posted by chknlytle

They are Bosch coils. And what I’m saying is that at one point it was P0302, then after changing plugs, it went to P0305, so I’d assume the coils are all good.

Update: switched plugs #5 with #1 and now getting P0301 cylinder #1 misfire. Because the plug looked foul, I will drive around a bit more and check #5 if it has become fouled. If so, will look at the fuel system (again) because all 6 injectors are new. Maybe fuel pressure sensor is bad?

#5 was misfiring and you switched plugs 5-1 and now #1 has a misfire? Get a new plug.

[chknlytle]

Originally Posted by 383vett

#5 was misfiring and you switched plugs 5-1 and now #1 has a misfire? Get a new plug.

I wish it were that simple. I've gone through 12 plugs (2 sets) in the last 2 weeks because the misfire keeps jumping around. I'll be ordering another set of plugs because at least one is fouled now, again.

---------------


I did an injector cutoff test today and it seems like all 6 injectors are fine. RPMs dropped the same across all cylinders when each injector was cut. Gonna pull plugs again and see if any more plugs are fouling.

All the codes I've been getting are for cylinder #1 and random misfire.

140001
140002
140010
140110
140101
140102

[Marty in NY]

Originally Posted by chknlytle

I wish it were that simple. I've gone through 12 plugs (2 sets) in the last 2 weeks because the misfire keeps jumping around. I'll be ordering another set of plugs because at least one is fouled now, again.

---------------


I did an injector cutoff test today and it seems like all 6 injectors are fine. RPMs dropped the same across all cylinders when each injector was cut. Gonna pull plugs again and see if any more plugs are fouling.

All the codes I've been getting are for cylinder #1 and random misfire.

140001
140002
140010
140110
140101
140102

You may have an Engine Control Unit that is failing. That is common to all your cylinders and controls the fuel injection and spark timing. At this point, due to all the things you've changed/replaced, I would look for something that is common to all the cylinders. That would be the ECU, the air intake...air meter, vacuum lines, etc. What dash lights are on now?

[chknlytle]

Originally Posted by Marty in NY

You may have an Engine Control Unit that is failing. That is common to all your cylinders and controls the fuel injection and spark timing. At this point, due to all the things you've changed/replaced, I would look for something that is common to all the cylinders. That would be the ECU, the air intake...air meter, vacuum lines, etc. What dash lights are on now?

I was thinking that too. Right now the CEL is on

[marc x]

You need itsa to properly diagnose these vehicles. Buy a copy from eBay or download a copy from somewhere. Could be faulty MAP sensor or air leak.

[chknlytle]

Replaced the spark plug and its gotten 99% better. Although this is what always happens, only time will tell. The remaining 1% consists of very slight hesitation at idle and an inconsistent rhythm at the exhaust.