Hi I have a diesel Vauxhall Signum and it has started shuddering under load. I have had a new turbo installed in March and a new fuel filter installed by Vauxhall last week, still shudders and loses power, place in second and burn off goes Ok for a mile or so than back to shuddering. I take my foot of accelerator and then back on again seems to work for a mile or so then back to shuddering. I use Shell Vdiesel to try to make sure fuel is best possible. Has three liter engine. Don't want to take it back to Vauxhall as they say no problems with diagnostics, no fault light so don't know what it is! Any ideas?
Hi Matt - Had a local mechanic come over and he has undertaken all your suggestions, down to changing the EGV sensor (two of them) but still same result lack of power. He is taking it back to his place and going to try to solve it. He is frustrated as I that it cannot be located/identified.
No fault comes up on electronic tester? Vacum is good gas flow good. He is a diesel specialist too.
Just goes fine till put foot on pedal to accelerate.....
Valves are fine too.
I you have any other thoughts that may come to mind, please let me know.
This could be a wiring issue as things tend to expand when hot and its possible a poor or partial electrical connection is being pushed apart on one of the major sensors so check the connection plug and wiring to the following;
Crank position sensor
Cam position sensor
Throttle pedal position sensor
Also worth checking the connections to the fuel pump for the same reason - unplug each in turn and give them a good squirt of switch / contact cleaner - Not WD40
and also unplug and inspect the main power relays and fuses for signs of overheating or corroded terminals - so the ones for the ECU and the fuel pump
And also unplug the wiring loom connections in the engine bay one at time and inspect for corroded or recessed pins.