ls1 misfire problem

[h41ry]

i have a vz ss ls1 233/242 110lsa and now have a misfire i have seems to be on idle and partial throttle upto about 4000rpm if i accelerate it feels like a vibration through the driveline it doesnt completely drop out any cylinders but i carnt put my finger on it. it seems to be worse when the engine is warm and but it comes and goes while driving. the mixtures are fine but the plugs are black except for 2 cylinders show normal. i have changed the plugs tried a smaller gap also changed leads and checked all conectors coils appear to be ok and injectors and fuel system are definatly good. im not getting any misfire codes have also tried a case relearn. the engine is healthy all cylinders are 180psi and i have between 4-7% cylinder leakage.
i have tried adding and taking fuel with the scan tool with no luck seems to get worse the leaner it runs and rich makes no difference added timing it makes it worse and taking timing does nothing if i hold the revs up in neutral i can here the misfire very badly. does anyone have any ideas what this problem could be i am at the point of giving up on this car as i am forever spending money on it and havent even had the chance to enjoy it yet

[statesman]

How much do you want for it? :laugh:

[ProperTuningOG]

Are the lifters good? Are the push rods hitting the head? Right springs? .......... "They should be, its all new," is not a valid answer.

[joecar]

Post logs and tune.

~ posted by phone ~

[joecar]

Did this just start happening...?

~ posted by phone ~

[h41ry]

Lifters and springs were recently changed also its been happening for a while now I have only just realised what's actually going on thought it was just a deivline vibration but it's definitely a misfire. What pids should I log

[Chevy366]

Are your plugs to cold in the heat range area?

[h41ry]

No they are standard

[5.7ute]

Check the ground points on the heads. Front of head drivers side, rear on passenger side.

[Chevy366]

Yeah, body grounds too, PCM and such.

[joecar]

Log these pids: GM.MFCYL#C where # = 1 to 8

( I don't remember if the cyl #'s correlate to actual cylinder numbers or to firing order )

[joecar]

Check:
- wiring connectors at each coil pack assembly;
- wiring connectors for injectors;
- wiring for CMP sensor.

[h41ry]

Found the problem turned out to be coils but shortly after fitting them I did a big end as the engine was low on oil

[joecar]

ok, thanks for posting back.

[h41ry]

Sorry guys I have had a busy week and some family issues. I found the problem and it was the coils it was running on all 8 but must have been a bad spark from multiple coils.