N54 misfire

[N54_joee]

Hi all, I've got a misfire that's really starting to p**s me off..
The cars a fbo (down pipes, intercooler, chargepipe, silicone inlets, cone filters, MHD stage 2+) it's a misfire under heavy load it's always combustion failure and started on cylinder 1 and is now 1 + 5.

So first off all the obvious, new Bosch coils, new 2 step colder plugs gapped to .020 , index 12 injectors replaced in 2018, both vanos solenoids replaced and has just been walnut blasted. I've also switched and swapped all components to see if the misfires would follow and they don't, always 1 + 5.

In the process of swapping the components and walnut blasting the intake ports the injector seals and decouplers were replaced along with the intake manifold gaskets.

Checked the coil and injector wiring with no faults, If I detune the car back to stage 1+ then it doesn't misfire as bad but will still occasionally (roughly every 1 in 4 pulls). I also have a custom map that targets 21psi and it still misfires. It never quite makes full boost on any map so I smoke tested the inlet system with the charge pipe disconnect and blocked and it seems to leak smoke through the pcv valve into the rocker cover into the inlet ports and out through the inlet manifold not sure if this is normal?

I carried out a compression test with all the spark plugs out and the injectors unplugged, all cylinders were between 165 psi and 180 psi.

The car has a slight wastegate rattle on cold start, but nothing too bad, I've been trying to get to the bottom of this misfire issue for over a month now and in the past week I have noticed that the car has a hesitation in second gear, low rpm part throttle, not bad enough to throw a code or a light but bad enough that you can feel it, since developing this I have also noticed that the exhaust occasionally pops and hiccups mildly on idle when hot.

Any help and or suggestions are appreciated

[DeRose666]

I have the exact same issue only cylinder 6 and 3 now. Only running 15 psi though. I changed the injectors out to index 12 and coded them. This helped a little bit still experiencing the issue myself. Hopefully someone has an answer for ya

[ramboz]

hello

i have the same problem

https://datazap.me/u/ramboz/29cf-29c...?log=1&data=21

I see that it could come from the pump which weakened... did you change yours?
not me but i don't know which one to change HP or LP ?

only on stage2+
stage2 works well (for now...)

crazy tooo

[Afam28]

Have any of you guy looked into fuel being the problem?
Maybe your not getting enough for what you're running…
LPFP, HPFP, fuel pressure regulator…

What do your logs say in regards to fuel?

[DeRose666]

Originally Posted by Afam28

Have any of you guy looked into fuel being the problem?
Maybe your not getting enough for what you're running…
LPFP, HPFP, fuel pressure regulator…

What do your logs say in regards to fuel?

Personally I did the injectors my next move was the hpfp

[Petro135]

What afam28 said. Check your mhd gauges and see your fuel psi for lp and hp. Should idle @700+psi hpfp and 70+psi lpfp and I'd get a few seals and flip injectors too. Index 12's are not bulletproof

[piotrek4000]

If your clutch slips under heavy load you'll get misfires, figured I'd pop in my two cents. Otherwise, might need better coils (Eldor, B58, PR, R8. Etc...)