More problems with CA - help! Odd stuttering and bogging on throttle

[tatsurou]

So I have my Ca18 fully forged and it RAN well. Barely broken in, done only 100miles with it. Wiseco pistons, K1 rods, pretty much stock spec for now apart from forgery. (I had similar problem with my old engine, but much less severe, it was going away once warmed up). Thing is, the engine idles perfectly but when you touch throttle it behaves like its under load, very slow revving. It sometimes backfires to the intake and you can hear that through the air filter. Once it warms up its a little bit better but not much. Hard to drive it like that, but once it reaches full boost (stock for now) it has a ton of power at about 4krpm. Below 4krpm it behaves like it has 60hp. When you hold around 20-50% throttle in one position you can feel like its getting more or less fuel, it jerks like it has more power, then less power, then more, then less etc .

Things I checked so far - boost leaks - unlikely, but possible, pipes are solid, gaskets new. Swapped TPS sensor to a known working one. Swapped AAC valve. HSS removed. No vacuum leaks. New temp sensors(Not oem). Checked FPR. Checked, flowed and tested injectors. O2 sensor disconnected but that shouldn't make the car so weak. Turbo developed a shaft play for some reason even tho it's a freshly rebuilt T25- is getting oil tho. On a side note, after 3 mile drive I noticed exhaust manifold glowing a little bit - so I suspect - lean. AFR gauge not connected yet. Swapped ECU. Fuel pump is new - Walbro 255 off of Ebay, bought last year, haven't checked that yet.

Help pls

[Oreos]

Sounds really silly but I know there has been a lot of fake Walbros going about. Did you buy it from a reputable dealer?

[tatsurou]

I think so but you never know. That is my next thing I’m gonna check - I have another old walbro kicking around and will hot plug it and run from a jug or something, see if it changes anything.

[pointz]

I would be checking both your cambelt timing and cas timing with a timing light.

Also have you checked your fuel pressure? If your regulator has failed you will only get pump pressure which isn't much as the reg will be allowing it to flow straight back to the tank.

[tatsurou]

Alright guys - fixed the issue, will leave the answer here for the future. Exhaust cam was an issue - the spline inside was loose and was making the car bog and hesitate, I tried swapping another CAS to check, but the spline snapped off completely and came out with the CAS. So swapped the cam and the car runs brand new now. Thanks for suggestions guys!