[2nice89]

Changed plugs, coils and the injectors in cyl 6 and the spark plug eventually gets wet with gas and then the car misfires..any1 have any idea why the plug only in cyl 6 keeps getting soaked with gas? When the plug is dry is runs fine until it gets soaked again?? Im at a loss of solution..hpfp and lpfp are new..never had intake valves cleaned either

[RallyRcrr]

Hi. That definitely sounds like you're not getting combustion in that chamber. The spark plug is wet with fuel because it's not being lit. One of the first thingst o do would be to go back over your work and double check the installation. Its highly probable something was missed if your system was working previously. Also, its rare, but sometimes brand new units (coils or plugs) are duds.

If you want a visual guide to help trouble shoot BMPDesign.com on youtube madeup a great troubleshooting video for BMW ignition coils and cylinder misfires. The video was done on e46, but the ignition system is similar to the 335s. Troubleshooting it would be the exact same steps.

[2nice89]

Originally Posted by RallyRcrr

Hi. That definitely sounds like you're not getting combustion in that chamber. The spark plug is wet with fuel because it's not being lit. One of the first thingst o do would be to go back over your work and double check the installation. Its highly probable something was missed if your system was working previously. Also, its rare, but sometimes brand new units (coils or plugs) are duds.

If you want a visual guide to help trouble shoot BMPDesign.com on youtube madeup a great troubleshooting video for BMW ignition coils and cylinder misfires. The video was done on e46, but the ignition system is similar to the 335s. Troubleshooting it would be the exact same steps.

I forgot to mention that the pressure across all cyl 1-5 was around 150.... And cyl 6 was 90... What would be the cause of this tho?

[RallyRcrr]

What type of pressure readings are the ones you're seeing? Fuel? Cylinder? How did you determine this?

[2nice89]

Originally Posted by RallyRcrr

What type of pressure readings are the ones you're seeing? Fuel? Cylinder? How did you determine this?

Cylinder compression test

[ritjeff]

Sounds like the piston ring is worn enough to prevent ignition, but I am not an expert

[ritjeff]

With my old VWs, I would dry test compression and then if one cyl was off by more than 20 or so PSI, squirt some oil in and test again. If it reads a good bit higher, the ring is not sealing properly. Otherwise, it is usually a valve if the trouble is only with one cylinder. Also, a bad ring will usually build up pressure with each stroke in a dry test.

[ritjeff]

Hopefully just a gunked up valve getting stuck. Just noticed that u haven't had them cleaned.

[2nice89]

Originally Posted by ritjeff

Hopefully just a gunked up valve getting stuck. Just noticed that u haven't had them cleaned.

Doesnt the head have to come off to fix it if its the valve? Or does the walnut blasting fix that? N could it really be that gunked why its messed up?

[Lifted07Duramax]

sub'd to see what fix ends up being

[enrita]

if you have low compression on cylinder 6 is probably a cylinder wall or ring issue. Sorry but probably you need a new or second hand engine.
This is my plug on cylinder 5 which had half compression.

[2nice89]

Originally Posted by enrita

if you have low compression on cylinder 6 is probably a cylinder wall or ring issue. Sorry but probably you need a new or second hand engine.
This is my plug on cylinder 5 which had half compression.

What was your fix?

[135Pats]

Sorry to say this OP, but the fix could well be a new motor. Ringlands could be shot, valves could be bent...That type of compression is extremely ungood, and quite rare on N54s. Do a proper leakdown test to confirm.

[2nice89]

Originally Posted by 135Pats

Sorry to say this OP, but the fix could well be a new motor. Ringlands could be shot, valves could be bent...That type of compression is extremely ungood, and quite rare on N54s. Do a proper leakdown test to confirm.

Car wasnt stock tho... You see my list of mods, i ran it to the ground lol

[enrita]

Originally Posted by O2nice

What was your fix?

remove engine, install second hand engine. i also thought it could have been a valve so i got the shop to remove the head and turned out to be the cylinder so i threw away quite some money on just removing the head.

[Jeff@TopGearSolutions]

You can clean the valves by removing the intake manifold.

With that compression number it sounds like you may have burnt up a piston or ring.

Enrita mentioned a second hand motor as an option but you could also just looking into rebuilding the motor. (you would need to outweigh the cost when you tear it down and find the problem).

You would need to have a professional look into this compression problem if your are not mechanically inclined. At this point without seeing the extent of the damage we are all guessing.

Run the compression test again. That's what I would do first.

Possible causes:
-Gunked Valve
-Bad Piston
-Bad Rings
-Bent Valves

[2nice89]

Originally Posted by Jeff@TopGearSolutions

You can clean the valves by removing the intake manifold.

With that compression number it sounds like you may have burnt up a piston or ring.

Enrita mentioned a second hand motor as an option but you could also just looking into rebuilding the motor. (you would need to outweigh the cost when you tear it down and find the problem).

You would need to have a professional look into this compression problem if your are not mechanically inclined. At this point without seeing the extent of the damage we are all guessing.

Run the compression test again. That's what I would do first.

Possible causes:
-Gunked Valve
-Bad Piston
-Bad Rings
-Bent Valves

Cars is gonna get looked at starting monday..hoping that its really a gunked up valve, but if its a piston, ring, bent valve the heads gonna have to come off, smh

[enrita]

get an engine built by BMW . its not easy to rebuild it 100% . its gonna cost more to rebuild instead of getting a second hand engine. Also much less hours involved.

[2nice89]

Originally Posted by Jeff@TopGearSolutions

You can clean the valves by removing the intake manifold.

With that compression number it sounds like you may have burnt up a piston or ring.

Enrita mentioned a second hand motor as an option but you could also just looking into rebuilding the motor. (you would need to outweigh the cost when you tear it down and find the problem).

You would need to have a professional look into this compression problem if your are not mechanically inclined. At this point without seeing the extent of the damage we are all guessing.

Run the compression test again. That's what I would do first.

Possible causes:
-Gunked Valve
-Bad Piston
-Bad Rings
-Bent Valves

With my list of mods...what do u think i could do to prevent this from happening again?

[enrita]

Originally Posted by O2nice

With my list of mods...what do u think i could do to prevent this from happening again?

is not about the mods but how aggressive you are running.
you should post some logs and more info about your setup like which map etc.

[bmvee]

I had the same problem on my R50 Mini Cooper, one cylinder tested 90 and the others did perfect 150. I pour a little oil in and redo the compression and got 120. I also replaced plugs and coils, but that didn't help of course.

Everyone thought it was fried piston rings, but that didn't make sense to me since the other cylinders are perfect. It turned out to be a cracked exhaust valve.

To check to see if it's a bad valve. Use compressed air, blow it through the spark plug hole, and hear where the air is leaking to. Hope that helps.

For future reference, this could be caused by lean conditions from fouled injectors. I had RC Engineering fit new o-rings and cleaned injectors for $25 each.

[JamesM3M5]

A high quality borescope can spot a bent or damaged valve or burned seat, melted piston crown, or damaged cylinder walls. A bit of oil in the cylinder during a compression test should bring compression way up if it is a ring or ring land problem.

A leakdown test will also quickly identify whether it is leaking compression from the valves, rings, or even a badly cracked head (extremely unlikely).