Hey there.

Car's been doing this recently and it's annoying as hell. It used to do it before once and a while but I kinda ignored it. It's really pissing me off now haha.

I usually always let the car warm up first and get hot before I move it.

At light throttle below 2500 rpms the car will stumble very hard. It bucks so hard for a split second it'll throw me forward, and then keep continuing on. It's really annoying. It's not when you are on the peddle more than half to wot. It's only light throttle around town. It doesn't happen every time. Once and a blue moon. I went over fuel trims and etc making sure everythig is dialed in. Doesn't help. When the issue happens it won't even register as a misfire, it's very strange and weird.

Yes car is modified. I can list all my mods, maybe somebody knows what's up. Mechanically the car works great. Lots of power, handles wonderful. Can't complain otherwise.

And for the record, there are no codes.

GM 3 bar MAP Sensors
Tial 38mm Wastegate, 13lb wastegate spring pressure
ZZP 82lb Valvesprings
Powell Racing 4.45 F35 Transmission with LSD
Bullseye Power / Borg Warner s256 Extended Tip Turbo, T3 .55 AR
ZZP LNF Exhaust Manifold
ZZP Stage 4+ Clutch
AEM Truboost Electronic Boost Controller
Triple Red Aeroforce Interceptors
ZZP Race Intercooler
ZZP Upper Charge Pipe
ZZP Lower Charge Pipe w/ MAF Relocation
ZZP 50mm BOV
ZZP 3" Big Turbo Downpipe, with High Flow Catalytic Converter
ZZP 3" Exhaust, No Resonator
ZZP Dump Tube
ZZP 3" Big Turbo Intake, with 3" Cone
Nitto NT01 245/40/R18 R-Compound Tires
Silver Enkei PF01 18 x 9.5 Lightweight Rims
5x114.3 Hub Conversion
Powell Racing YYZ V2 Springs
KONI Yellow Struts, Front and Rear
Powell Racing Anti Oil Starvation Pan
Powell Racing XXX Bar
Powell Racing Harness Bar

Appreciate the help.

Cheers.

 

This used to happen on an old Chevrolet pickup of mine right before the in-tank fuel pump went completely out. I'm not saying it's the same for you, but if you're nose-diving it has to be fuel or spark.

 

HPFP was replaced last year with a brand new unit. Not sure if the in take unit needs to be replaced? Yeah I am assuming it is spark or fuel related. Do the injectors go on these cars???

 

Log all individual cylinders for knock, misfire, injector pw, plus commanded lambda vs actual lambda and commanded rail pressure vs actual fuel rail pressure (along with the normal basic stuff) and see if you can catch it in a log. Take note of anything unusual between all of those (ei; spikes/dips)

 

Yeah that's a good idea. I know what's going to happen - I'm going to log it and nothing's gonna happen haha

 

raver0789 Did you sort out a solution for this problem? I have the same issue intermittently and could never find any useful information on it. I discovered that my GMPP 3bar MAP needs to be removed and cleaned when this symptom comes up. Usually doesn't show up as a DTC either...

 

What spark plugs u running