Missfiring after a auto to manual conversion

[elohim_imanu]

So every since the conversion if have a miss-fire. It seems to happen in the rev range of 1100-2500.

The car was sitting for a few months during the conversion.

1. Changed the plugs

2. Coil packs are brand new

3. Unplugged coils one by one, they all display similar behaviour  

4. Sprayed all over vacuum hoses etc with brake cleaner, can't hear anything change

5. Vacuum tested when running, looks normal.

6. Unplugged the O2 sensor, no change. ecutalk is seeing voltage. 

7. Swapped CAS with another good one

8. Resistance check the coil loom

9. The battery was disconnected for weeks during the conversion, so the ECU has been reset.

I have a consult (ecutalk), but I don't really know what to look for, other than error codes, which there are none.

I am running out of ideas.

PS It is a N/A

[IM-32-FK]

Usually with all the skylines I’ve owned issues at 2500rpm always seemed to be related to the air flow meter. Usually when the AFM is dead it limits your revs to 2500. Your one might be dirty as f**k inside it, or you may be even using the wrong one. So clean it with contact cleaner or afm cleaner. Just make sure one side of the afm has the mesh on it though, because removing that also causes problems. Also check the afm wiring, it might be loose or come off.

I would also clean the inside of the boost solenoid. 

[elohim_imanu]

Thanks. I will clean it and check the wiring. But I have not changed it during the conversion. I think it is OG. I wish I had a boost solenoid. NA.

It does rev right out. It is just missing a bit and feels like a vibration in the lower revs.

[elohim_imanu]

Cleaned the AFM and throttle body.

Still no change.

I am starting to wonder if the flywheel or pressure plate is out of balance and what I am feeling is a vibration.  It does increase with revs and there is a small vibration on the clutch pedal in the high revs. 

[elohim_imanu]

It was indeed the pressure plate, which needed balancing. Nismo!!

[GTSBoy]

On 9/22/2023 at 4:23 PM, elohim_imanu said:

It was indeed the pressure plate, which needed balancing. Nismo!!

It's not so much Nismo's fault. It happens. I just replaced my clutch for exactly the same reason. It got out of balance as it wore.

[elohim_imanu]

Yes, but this was out of balance brand new.