Limp mode

[trevor1985]

Well my nav did it again, 2012 st nav only 7000 k's on it. Just wondering if anyone can shed some light on this I have a chip it chip and it keeps going into limp mode when I put the boot into it. Take it out no problems my brother reckons way to much torque for standard exhaust he said it needs to breath abit more its just getting to backed up. Anyone else had similar issues with chipit??

 

[Old.Tony]

It could be the suction control valve on the fuel pump.

Does it only happen just as you back off the throttle? Could also be an overpressure issue. When you back off the throttle, the rail pressure is still high but if the chip removes the resistance from the return signal, the ECU will see the higher pressure and might trigger limp mode. To test that theory, back off the throttle a little more slowly instead of just releasing it.

 

[JPMC]

It will be the chip causing it to over pressure and then the pressure limiting valve will be dumping the excess back to the tank and activating limp mode as the ECU will think there is a problem. Nothing to do with exhaust.

You have a couple of options to cure it.
1: Turn down the chip
2: Get a new higher rated fuel pressure limiter from Chip-it
3: Modify your factory pressure limiter to allow higher pressure.