Strange starting problem with Suzuki Grand Vitara 1.9 DDIS

[anawfulhoore]

Hi All,

I'm starting a new thread for this as I piggybacked an old thread looking for a bdm..

This 2008 Suzuki Grand Vitara 1.9 DDIS (renault F9Q engine) randomly wouldn't start after being left to cool.. crank sensor was suspect and there was crank sensor fault code when scanned after this first happened so the crank sensor was changed. however sometimes it randomly still wouldn't start after being stopped. No fault codes, but live data was showing that rail pressure seemed to be "frozen" at a value somewhere around 295 bar (same value as when idling) after key off (should drop back to 0 bar). Also while cranking the pressure regulator duty cycle would stay below 20% (confirmed by scope / multimeter) when this would happen. live data RPM was reading ok (300 RPM) so crank sensor was working, however rail pressure would be still "frozen" at old value, while the actual voltage at rail sensor would be about 0.6V, confirming that there was not enough rail pressure (should be about 1V @ 300 bar)

if ECU was left to power off completely after switching off key (waiting about 1 minute to hear main relay drop out) then the rail pressure would be back at 0 bar, and the fuel pressure regulator duty cycle would "kick" to 50% after key on. Then engine would always start first time.

due to the "frozen" rail pressure I suspected an ECU / software issue so I found a backup bdm on here, and flashed this to a spare ECU, with its own EEPROM. comparing the dumps (with same bosch no 0281 012 657 1039S13917) there were differences, so maybe it had been modified..

but the problem remains.. now I'm beginning to wonder if this is "normal behaviour" for this car, and we are chasing a "bug" and original fault may actually be cured.. has anyone else seen this ? or anyone have a Grand Vitara to compare with ?

I can post up the bdm I pulled from it if need be..

Thanks,

stylers.

[anawfulhoore]

Just to update this.. after a bit of studying and trying another ECU etc it appeared that this fault may be "normal behaviour" as we were able to replicate it by not fully switching off the key, and it seems that the driver regularly did this when stopping the car..