K20Z1 dropping a cylinder

[DaRKNT]

So, I took my car out for a drive and a refuel last night - and the car was running fine, even driving it spiritedly.

Fired up the car this morning... drove it for a good 15 minutes and all of a sudden it drops a cylinder. Cylinder starts cutting in and out while I'm on the freeway. Had to give the car a bit of throttle to avoid getting rear ended and to my surprise, it kicks back in at/over 3k RPM over a certain throttle percentage. Some times it's running fine, others not.

Got to uni and had a mate bring me some tools (Thanks Rookie!)... here's what I've done so far:

- Pulled sparkplugs and inspected. Polished them clean with a bit of steel wool.
- Isolated dropped cylinder to Cyl 2
- Swapped coilpacks to see if missfire moved (didn't)
- Swapped sparkplugs to see if missfire moved (didn't)
- Checked oil... not milky

So at this point, my cylinder 2 is dead 50% of the time... but kicks back in when putting my foot down a little. Here are my thoughts:

- Dirty injector #2? Looked at datalogs and duty cycles are consistent across all 4 cylinders
- Lost compression? Don't know how, motor is very healthy
- Bad part of the coilpack harness and cylinder 2 does not fire properly
- Valve stuck open? Doubt it as it kicks back in?

I'm still learning so I could be wrong, but I have an ex-mechanic uni mate to help me out haha.
Any ideas?


(Also, someone have a compression tester I could borrow for a night or two?)

[tinkerbell]

duty logs wont show a dirty injector - only a injector flow test will

(duty is amount of time computer holds injector open)

did you take pics of the spark plugs?

was it (no.2) black or white?

could be harnes - check for damage? any water ingress lately?

[DaRKNT]

I can upload the datalogs if it helps at all tinks.

I didn't take pics, but the spark plug was white but mostly clean.

I did have a look at immediate vicinity around the harness... didn't see damage.

Umm as for water ingress, nothing springs to mind. Last night, when I refuelled, I did fill up my washer fluid and the filler neck popped out as I was doing so... no water near that harness but I'm guessing some around where the filler neck was.

[tinkerbell]

white = lean = so it is not getting enough fuel/not compressing enough

black = rich = spark plug not firing

what colour where the other three?

[DaRKNT]

That's weird. I know the car is running rich, I can often smell the E85. It's tuned on E85 btw. And I get a fair amount of exhaust pop.

All spark plugs were consistently the same color. Not white enough to be indicating lean in my/my mechanic mates opinion.

[sleepingperformance]

Cars running on e85 will always have the corn smell, regardless of fuel mixtures.

Exhaust pop can be caused from lean mixtures, as well as rich mixtures.

How did you isolate what specific cylinder it was that was causing the issue?

Also what injectors are you using and have the injectors been scaled correctly in the ecu?

[DaRKNT]

Josh, when I changed spark plugs last, they were blackish indicatimg rich as well.

I isolated cylinder by disconnecting coil pack till there was no change in engine sound.

I don't think it's the tune, I'm on the same tune I have been on for the greater part of a year. Injectors are RDX.

[tinkerbell]

bad batch of e85 could be an issue?

[DaRKNT]

Dave, (I hope I got your name right tink), how would that explain just one dead cylinder? Other than clogged injector?

[tinkerbell]

Dave, (I hope I got your name right tink), how would that explain just one dead cylinder? Other than clogged injector?

Just using Occam's razor - when did the problem start?

Either that or its the water?

[sleepingperformance]

Were the plugs that were removed at the last change fitted while the vehicle was still on 98ron or strictly e85?

I ask that as we run copper plugs in our race cars and after 8 track days and upwards of 60 hours on the dyno, we have not had a plug go black on us since we made the switch to e85

It is very hard to say much more as we would need to test drive the car and inspect certain aspects before making an informed decision

[DaRKNT]

Just using Occam's razor - when did the problem start?

Either that or its the water?

The problem started this morning. Just trouble shot a bit more, I have spark on coil 2, I swapped injectors around... nothing. Cylinder 2 is completely dead now.

Sounds like a rexy. Fuck my life.

[DaRKNT]

Were the plugs that were removed at the last change fitted while the vehicle was still on 98ron or strictly e85?

I ask that as we run copper plugs in our race cars and after 8 track days and upwards of 60 hours on the dyno, we have not had a plug go black on us since we made the switch to e85

It is very hard to say much more as we would need to test drive the car and inspect certain aspects before making an informed decision

Replaced once on E85 (or just before I came off 98) at my major service (80,000 kms), they are IK22. Will swap in new ones in the morning. If I can't figure it out... I might book in an appointment with you. Will have to tow it in from west side though :/

[DaRKNT]

https://www.dropbox.com/s/utj08dua5j20yta/Log1.csv?dl=0

https://www.dropbox.com/s/0bpk4lheeh0z4s1/Log2.csv?dl=0

Haltech Data Logs for anyone interested.

[gunpoons]

Are the Rdx injectors big enough? They are only 410 right, that's not a huge jump over stock