Lazy timing vs Knock...

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Sergeant
Jul 27, 2017
334
135
0
Ride
335i
Hi,
I recently began doing a few pulls to measure my 100-200 times with draggy.
I'm DCT on a European E92 335i. IJE0S if that matters. Spraying port meth injection. Running a JB4 and a trebila back end flash.

I normally use 1 step colder plugs. These seem to work best for me. I gap them at 0.45mm (0.0177") and have the BL kit with R8 coils. I know that gap may seem small but it has worked well for a number of years up to around 25 psi. Fuelling appears good during pulls.

On recent logs cylinder 5 has often shown to be lagging behind in the timing. Where cylinders 1,2,3,4 and 6 may be at 9.7*, cylinder 5 might be at 7*.

cylinder 5.png


cyl 5 laggy.jpg


The interesting thing though is that cylinder 5 doesn't get to x degrees of advance and then drop back a few degrees indicating knock. It always has lower timing than the other cylinders during the whole rpm range. A compression test has shown all 6 cylinders to be almost identical.

I don't know the logic of the DME. Will the DME not allow cylinder 5 to go to the same timing as the other cylinder because it sounds noisy (to the knock sensor) from the start or possibly the oil vapors from the PCV has lowered the octane in that cylinder? I recall many threads in the past on other forums saying cylinder 5 is often problematic.

I've tried changing spark plugs and changing coils. I haven't tried swapping an injector. I don't have an injector tool to swap the injector seals. (Maybe if I swap 2 injectors quickly, that won't matter?)

Anyway. On 2 step colder plugs the timing was alot worse and on multiple cylinders.

2 step colder plugs.png


So really my question is why cylinder 5s timing is always lower than the other cylinders. Is it knock related or something else?
If it was a lazy coil then I'd expect a misfire to eventually happen but 5 doesn't misfire. The spark plug has been swapped with others but the issue remains.
 

nyt

Corporal
Sep 15, 2019
176
178
0
Ride
2010 335xi
You say it's always low, but it's not. It's with the rest of the timing earlier in the run, then it's showing timing pulls and stays down.

Check your fueling for that cylinder, maybe run a leakdown and compression test as well.

Get an injector tool and some fresh seals as well so you can swap
 

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Sergeant
Jul 27, 2017
334
135
0
Ride
335i
You say it's always low, but it's not. It's with the rest of the timing earlier in the run, then it's showing timing pulls and stays down.

Check your fueling for that cylinder, maybe run a leakdown and compression test as well.

Get an injector tool and some fresh seals as well so you can swap

Thank you, you are correct. I've looked back on 3 other runs and it nearly always goes low at 5300 rpm on the first gear going WOT.
Did have a blocked meth nozzle earlier. I suspect now a leaking meth connection đź‘Ť
 

kulixo

New Member
May 26, 2020
5
0
0
Just wanted to say replacing injector seals was fine without any fancy tool. I've used the plastic end piece of a sillicone tube or a pencil combined with some oil multiple times to fit the seal. Then use some electric tape and a hose clamp to compress the seal.
 

SlowE93

Lieutenant
Jul 2, 2017
731
274
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E93
Thank you, you are correct. I've looked back on 3 other runs and it nearly always goes low at 5300 rpm on the first gear going WOT.
Did have a blocked meth nozzle earlier. I suspect now a leaking meth connection đź‘Ť
Very common....especially in that rpm range.
 

SlowE93

Lieutenant
Jul 2, 2017
731
274
0
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E93
Mine always dropped at 5200rpm on cylinder 5 without fail, some do it and some don't.

Don't know anyone that found a fix for it.
My understanding is its more a IJEOS thing...more people would need to chime in though.