Hey guys I'm having major issues with my 2009 SV6 SIDI too with it dropping cylinders and I'm hoping you might have some ideas as my mechanics are fresh out and I'm about ready to torch my car.
First time it occurred was in late July. It was booked in to the local Holden dealer for it's 105km service later that week so I had it towed there. They diagnosed the issue as a faulty injector in #2 so they replaced that, serviced it and 1.5 weeks later I was on my way. Driving it down to Queensland Raceway for the V8 Supercars after I picked the car up I stopped for a drink. Start the car up again and CEL comes on. Car seemed to be running ok but took it to nearest Holden dealer(Llewellyns, Ipswich) and they diagnosed PO157 fault, cleared it and I was on my way.
A couple of weeks later I've run to town(90km), run around town to a few places and stopped for lunch. Come out and car is hard to start and running rough. Call RACQ who's tech comes out and puts the scan gauge on it for codes P0304, P0157, P0299, P0089, P0300, P0306. He asked if Holden had changed the spark plugs or suggested it and I said no they hadn't. He said it was quite often the cause of these dramas in the SIDI's and suggested I had it done. Once codes were cleared car ran fine but I had it towed to a mechanic he recommended to be on the safe side. They tested it multiple times and couldn't replicate the faults. Taking the RACQ guys advice we put new spark plugs in it and did a throttle body and intake clean.
Fast forward to the end of September and I've driven the car about 3/4 times since I picked it up from the mechanic. Decided to give it one last final run before heading to Bathurst for the 1000. Drove about 130km in one direction and started on my return journey when about 30km down the road coming out of some roadworks(70km zone) and I accelerated gently and she shudders, CEL comes on and dropped cylinders. Get a tow back to same mechanic and my Bathurst dreams came to a screeching halt. I don't have a list of codes for it this time but it dropped #1 so I'm assuming it was P0301 code. Mechanic kept the car for several weeks driving it daily and unable to replicate the issue again. Coils on #1 and #2 were swapped to see if #2 was affected next time so it could be put down to a faulty coil.
Again fast forward to a lovely rainy Saturday in November and I'm travelling in an 80km zone up an incline and there she goes again. More dropped cylinders! Upon the mechanics advice to try it I started the car on and off several times but this only sent it into limp mode. So another call to RACQ for a tow and I'm starting to get to know the tow truck driver a little too well. Dropped it off at same mechanic. Unsure of which cylinders were dropped this time or which codes but it apparently threw some fuel pressure codes too. At last something to work with! Compression tests were done and #1 failed a dry compression test but passed the wet compression test. Diagnosed as faulty #1 injector. Upon pulling off the intake manifold and removing the fuel pressure sensor they discovered the sensor was broken. Bingo we finally have an answer for all the issues. So I hit Holden up for a new fuel pressure sensor as they were the last people to touch that one. They came to the party and gave me a new sensor, injector #1 was replaced and I was on my way.
About 15km down the road going down an incline in a 100km zone there she goes again. This time she's dropped #1, #3 and #6. Only other code was P0300. Mechanics are trying to get approval through the warranty to change the remaining 4 injectors. I'm starting to think it's an ECU issue.
Please have you guys got any ideas as I'm frustrated out of my wits? This dumb A$$ car has basically been at the mechanics since July and I'm paying on something I can't even drive let alone sell. It's also a huge pain in the butt having to get someone to run me the 80-90km into town every time I need to pick the damn thing up and it's costing me a fortune in hire cars every time I get stranded in town.
