My ‘87 is bucking me forward

[nickyclyde]

I’ll try to describe this as articulately as I can. My 930 has a new turbo , 964 cams and a header muffler system. Other than the ignition box replacing the original Cdi, it’s stock. When I accelerate, especially in 2 nd or 3rd gear and reach say, 4000-5500rpm, if I back my foot off the accelerator a little bit too abruptly, the car acts as if fuel was cut completely off and the engine and shifter buck violently. Feels like I could break one of my new engine mounts. If I feather back the throttle real softly it doesn’t happen. So im driving along accelerating briskly, not flooring it and I’m not gentle and perfect on pedal let of to shift or slow down it feels like fuel cutoff situation. Any ideas? Also , my boost gauge pegs the 1 bar mark easily. I was told I have a 1 bar spring but seems like with a 1 bar spring it should be slightly hard to peg the needle

[RarlyL8]

What you are describing sounds like the BOV is not operating. If air is not recirculated around the throttle during lift throttle events the boost pressure will bounce off the throttle plate and pulsate back and forth from the turbine outlet to the throttle body until the turbine wheel slows down enough to offset the buffeting. Causes a shutter or bucking.

[nickyclyde]

Thanks Brian, I’ll check it

[Pat RUFBTR]

I give an idea like that, maybe that your new turbo much more blows hard than that of origin and what your wastegate of origin is now under sized.