Back to Forum
Post a Response
    Vauxhall Signum/Vectra C 2.2 (Z22YH) Archived Message

    Posted by Dave Hill on January 7, 2008, 8:46 pm

    Just thought I would share this one with you guys. It’s a 2003 Vauxhall Signum (same as a Vectra C). It came into us with a single cylinder misfire & a more general flatness under acceleration. A scan provided the following code P0301 (Cylinder 1 Misfire Detected) & a quick inspection confirmed that the insulation had failed on cylinder 1 coil area.

    A new coil pack & set of plugs cured the single cylinder misfire, but still there was a general flatness in performance on the road. When I re scanned it, there was a new code P1191 Unknown DTC on Autodiagnos. Fortunately the Launch & Snappy have this code definition loaded.

    P1191 fuel rail pressure sensor circuit range performance high input/low input or fuel pressure system malfunction. Nice definition from the Launch tool!

    This is a new system to me & some head scratching began. This is a direct injection setup where a pump in the tank supplies a high-pressure pump, driven by the inlet camshaft. The low-pressure pump delivers approximately 4 bar (64 psi in my case) & the high-pressure pump boosts this pressure to a maximum 120 bar (1740.5 psi).

    The fuel rail resembles a common rail diesel setup, with a pressure sensor (3 wire) & a pressure regulator (2 wire). I set about taking a capture of both these components in an effort to understand what was wrong.

    Here you can see the duty cycle increase as I floor the throttle but the pressure sensor output doesn’t rise as I expected.


    Unfortunately I don’t have any kit that will “physically” test the pressure in the rail & I have to rely on live data, which unfortunately Autodiagnos lets me down on again. The Launch & the Snappy both cover this though & they confirm that the ECU is seeing the same pressure sensor output as I observe on the scope. Also they showed the desired rail pressure of 6927.03 kpa (1005 psi) & an actual rail pressure of 525 kpa (76 psi)

    I need to prove if the sensor is capable of reacting to a pressure increase, so I use the workshop airline pressure to test it & sure enough I get a reaction albeit not great.

    The high-pressure pumps are a known issue on these & as this was a trader’s car I decided to strip the pump to see if it was repairable. It wasn’t, but it was fairly badly contaminated with dirty brown fuel, like you see when you drain a dirty fuel filter. I have ordered a new HP pump & will post the results.

    The ironic thing is that I have had three of these in recently with various faults & I have missed the opportunity to take captures of various systems to gain the knowledge needed. I have to admit that I am disappointed that Autodiagnos didn’t have a definition for the DTC & worse still no rail pressure PID’s. The devil is in the detail with these things & without detailed live data we are left with more uncertainty in a difficult world.

    Cheers for now.

    Message Thread:


Copyright © uk autotalk