Engine shuddering when hard acceleration
 

Hello,

I am having a annoying issue with my scooby, after messing with my APEXI boost levels the engine started being funny with me so I changed everything back to how it was and unplugged battery to drain solenoids. Car ran fine but then started having issues after I properly drove it about, It was shuddering on hard acceleration almost as turbo kicked in. In my mind this is a fueling issue, I had recently filled it with 95 as I was desperately out of fuel and believed that the poor fuel quality may of caused this so I drained it and refilled with 97 but I feel like maybe in hindsight 99 would of been what I needed, my question is would 97 cause this problem or is it something else? Should I drain the tank and get some 99 in there? I was gonna go back to my mapper and get it reconfiged as I thought I messed something up but maybe thats not the case as it got better, fuel filter or sparks possible too?
Any help or opinion is much appreciated.

Current Specs:

• TD05 Turbo 16g
• 550cc pink injectors
• 244 Walbro Fuel Pump
• Ally race radiator
• Large Intercooler
• Ram Air Filter
• Decatted Straight Thru
• On standalone ECU APEXI with turbo timer
• Big Brakes
• Mapped by the Jolly Giant (Checked by Duncan at Surry RR) - 340BHP

What settings did you actually change?

The boost option; turned it up then turned it back down

How high, if thats all you did it start by checking the plugs, easy and simple to rule out, also if you think its fuel the car may be running lean and the plugs will confirm this,
Do you still have the OE ECU, as from memory you cant read ECU error codes in Apexi, if im wrong please speak up as its a while since I had any dealings with a Apexi FC.

I turned to 1.2 it was the max of the four settings, the car gave me a engine warning so switched it back from their it started. I do not have the oe ecu, Its strange as it ran correct for 2 days after disconnecting battery for few hours. Its tuned to take 99 and ive realised that is something that its missing as ive only put 97 in but still unsure if its related.

What error did it give you failed to mention before?
And is there anything else you may have missed?

Nah just the generic engine warning on the dash, only other thing to add is obviously im losing huge power up hills mainly, im hoping to drain the fuel and put the 99 in to see if thats the problem but when driving atm when driving im not daring to hit boost as its so jerky

Whats is a generic error? lol

No error just the engine warning light illuminated n the dash, as soon as i changed it back it went.

I dont really know how to explain it its just the standard engine warning light on dash

iirc the check engine light on an apexi ecu is utilized in a couple of ways. It can be used if a sensor is down plus it can be a knock light. If you look through the different menus you can also find the sensor which is dodgy iirc it flashes a black box around the readings. What car is it.