BPT/B6T Problems?

[SLY 323]

So I have a few problems I've been trying to get sorted.

Problem 1;Recently put a VF10 in my BG BPT. Now my problem here is without a boost controller just with the wastegate setup standard, on full boot wont boost any lower than 15 psi.1st gear around 11psi, 2nd around 13psi then 3rd and 4th 15psi and 5th somewhere above 16psi but not willing to test it. Why is this? Isnt it supposed to stay at standard gate spring rate?

Problem 2;I have a BF SS with a B6T with a VF12. Now the problem here is between 2500rpm and 3000rpm on about half throttle I get a massive flat spot point where the car bogs right down,then whwn boost comes up high enough It goes away. Now ive changed plugs, leads and rechecked timing @ 12ºBTDC.Any help with my problems would be great!

Note, this is a repost for FL.com

[rodhog]

Problem 2 sounds like a issue with the fuel system but mainly its getting a incorrect signal or it's not responding quick enough. If it's something new and was fine before and nothing has changed I'd say it's like a Map sensor or air leak issue.

[SLY 323]

Ok, well I don't think it's air leak cause wouldn't it idle funny or something? I also changed fuel filter. It's been like this since I bought it. How would I test if it was the map sensor?

[TheMAN]

your boost signal source to the wastegate actuator is restricted causing insufficient pressure to overcome the wastegate actuator diaphram... ensure that your signal hose does not have a restrictor pill inside and that the hose is not kinked

if that checks out, then your wastegate is probably too small or you have an exhaust back pressure problem

[SLY 323]

Hose is fuel line with no kinks or restrictors.
Wastegate has been ported, though I do have a 3 inch exhaust with just a muffler, though the vj20 I had on it never had an issue

[rodhog]

it might be leak underboost only, sounds like my old intercooler crack. I put a crack that opened up on the top end of the tank that only opened under boost pressure.

If the Bf is still running stock ECU then the AFM needs to be looked at in, but if it's had any other electrical or ECU modifications then you need to look at why it's bogged up. hard to diagnose with out know the car or it's full history. If you have never had it running right well it's another up hill battle.

oh and are you running that actuator line direct for the cover over turbocharger?

[SLY 323]

Still stock ecu. So where do I start? Lol

[rodhog]

stock ecu and non standard turbo. reduce the timming back a bit. see how that goes any improvement. IF you know how to access the standard ECU's fault system even better if not. I'd say and it's not hitting boost cut or has it been over ridden. it's reading a massive intake of air compensating by dumping fuel -drop timming advance = bog until it reaches the a parameter it's set for. A vf12 over stock has massive difference in flow. on AFM car with VAF it's instant. but on the other hand Airflow is airflow and it really is not well it is better but like I say I can't tell without being on the car. Mem serves we used T25 and T28's off Sr20's in the early days with out too many issues. So it makes me wonder if the VAF wiper has a fault. Question does it hit boost/fuel cut at all.