Gsr swap running p28 s300, no issues accelerating at all it runs great drives great.....until I come to slow down after a cruise, I left off gas and push clutch in. When I try to downshift and accelerate the car falls on its face, no go at all. It'll actually barely idle and make me stop the car. It'll die and then I can start the car immediately and drive normal again. Wtf is that? No codes, fuel injectors were cleaned, possibly fuel pump? It does not sound strong when I first turn key on and hear it run it'll give a loud whine then lose steam and turn into a weak whine, but that's just me guessing honestly. It drives fine I can accelerate hard all I want. Not sure what's going on but it's not safe to drive like this.

 

well from what youve told me so far i can think of two things that may need fixing here

the first is the main thing
when you loose power after a nice cruise
the motor kinda buckles when your trying to gain speed
and if you turn the motor off and turn it on again you have your power back

this is a classic fuel pressure regulator or fpr for short problem
when these start to go back they begin to stick
and your fuel pressure is all over the place
and so you dont have enough fuel getting into the motor or maybe even too much
and youll get the problem your having

to check your fpr you can run a simple test on it

heres a how to

 

Thanks for reply. I also just thought of this......my fuel tank vent line at the firewall is cut and pinched closed ........not sure what I should do about that or if that is affecting my problem. Never had a problem prior to this, was running a b16 and b20v with none of these issues. I don't want an aftermarket regulator so I'm gonna grab a new Delphi unit. Motor is mostly unchanged from how it was received from HMOTORS. Also going to plug a laptop in and run a data log and see what I can see there. Not sure how to check fuel pressure with my gauge since I have a tucked line kit.

 

you connect the fuel pressure tester to your fuel rail if you hid all your lines and no longer have a oem fuel filter

and yea that fuel tank vent line should be open
the tank needs to vent if it doesnt then you will begin to get random leaks in the future