RB30 Misfire - Throwing parts at it ain't helping.

[Birdpirch]

G'day legends, 

The misses has an R31 GXE Auto which I recently did injector rebuild on. 

I removed the old injectors, had them flow tested and a new seal kit done as there was previously a leak. 
Prior to removal, the main issue was the above mentioned fuel leak, but since completing the reinstallation of the injectors, there has been a really intense misfire. 

-The injectors flow tested perfectly
-A lot of care was taken when installing them, so I don't believe they are will be the issue as of yet. 

So far, I have replaced;
-Dizzy cap and rotor (they were both absolutely cooked)
-CAS (some sort of water entry got in there and made a mess)
-Plugs (Were disgusting)

>The AFM is second hand, and was replaced when the original one died. 
>The Injector plugs are pretty cooked, so that will be my next replacement as it is required anyway. 
>I will need to test the ignition leads, however they were only done about 2 years ago
>Not sure how to check the ignition coil, but seems unlikely it would die straight after the above work was done. (not sure when it was replaced last either)

Sometimes I wonder if I have swapped some electrical connectors around by mistake, but I am confident that they are all in their correct locations. 
I did pressure wash the whole engine bay after the replacement, is it possible I soaked the ECU? (Unsure of ECU location).

Any help would be absolutely amazing, this is doing my head in. 

Cheers!

[niZmO_Man]

ECU is in passenger side footwell.

Take the dizzy apart, make sure the CAS disc inside is clean.

I had misfire issues because the CAS was rusty and spilling dirt on the disc (sensor wasn't reading properly hence misfire).

Also does it idle fine? Try unplugging AFM, it should idle and rev to 2,000 rpm fine.

Loads of info on R31 Skyline club wiki

[blind_elk]

On 8/17/2021 at 3:50 PM, Birdpirch said:

... I did pressure wash the whole engine bay after the replacement ...

 

This probably won't have done you any favours. A wet connector block somewhere could be upsetting things. Try some WD40in all the connectors.

[niZmO_Man]

CAS connector

[Adam91]

Go back to basics man. Compression test. A constant reading is good, a 30 psi or more difference between adjacent cylinders is bad. Disconnect one injector at a time and reconnect until you find the bad cylinder. A good cylinder will run rougher with the injector disconnected. The bad cylinder will do nothing with injector disconnected. Then check for spark. Use a gap tester or remove a spark plug on each cylinder. Don’t forget to remove the fuel pump fuse if you pull the plugs to test. 
 

if all that checks out ok, check for vacuum leaks and injector wiring. 
 

if you’ve pressure washed it you will probably have water somewhere simple, usually in the dizzy cap or spark plug tubes 🙂

[Dasmbo]

Had a bad misfire problem similar to yours turned out to be a bad connection with the wire on my starter motor