Misfire after engine rebuild - 3.2 Carrera

[shinrai]

Obvious misfire noticed when running up for the 2000rpm for 20 mins after a complete rebuild. Ran for a couple of mins thinking maybe residual bad gas in the lines or air in fuel system to no change. Everything is new including injector harness. Swapped in old harness to eliminate a bad new harness. Timing is good. Spark everywhere. New speed and ref sensor gaps good. Injectors refreshed by Witchhunter.

Here's what the plugs looked like after running for a couple mins at 2000rpm. Safe to say there's an issue with 2,5 and 6?




I cleaned up the ugly ones already.
I'm stumped here. This may take a few beers.
Anything else other than bad injectors to cause this? AFM? The schematics for the harness in the Bentley manual are rather interesting





TIA

[emac911]

crossed plug wires?

[shinrai]

Plugwires triple checked. 1 - 6 - 2 - 4 - 3 - 5. Going on in my head all day

[Spetrow]

How long did injectors sit after cleaning? They could be sticking.

[shinrai]

Roughly three months. Too long? I'll hit them with the stethoscope to see what they sound like. What's the workaround to getting them unstuck?

[wazzz]

Remove injectors, at least those for 2, 5 and 6, and check them. DC resistance should be around 2,3 ohms.

As a quick check to see if they are clogged, you can try this trick that worked well for me.

[Spetrow]

Most injector cleaner firms want them installed and run shortly after clean & seals. Others have used a 9v battery and carb cleaner but i would clean #1 plug and swap 1 and 2 injectors, run it for short time to see if the issue moves to #1. Use of a scope will show the fuel burn.

[isby]

My injectors sat for about a month after I got them back from servicing, and I had a problem with one of the cylinders not firing. The problem of sitting injectors was also discussed by Heidi and Franny on their YouTube channel when they were sorting their white 3.2 Carrera.

[PeteKz]

Do what wazzz suggested. Move the injectors and se if the spark plug dirt follows the injectors.

Is the engine back in the car? If so, go drive it. Get it fully warmed up and exercise it. That may clear the injectors.

[shinrai]

You guys are kings. And this is a great community.

Turns out 3 months sitting hung up 3 injectors as you suspected (I was surprised it ran on 3 cylinders).
FWIW I pulled one rail and hit them with CC and carefully hit them with a brief 9V shock after some slight taps on the injector. The other rail just hit it with a shock and you can clearly hear when they're operable. Be brief on the 9V and you'll be fine. Some say not to do this. Most say it's fine so long as you're careful. Most are right some of the time

Thanks to all.

[Spetrow]

Excellent results. Seeing new plating, fan work and quality, it looks like you put in a lot of effort in the overhaul. Do your break-in and you should be good.