WM Caprice: "Check Engine" warning - fuel trim both banks - ideas?

[skip100]

I've got a "check engine" warning, with the orange dash indicator hard on (has never flashed yet). The dealer said the error is "fuel trim both banks". They reset the error, and it didn't re-occur for them. It HAS re-occurred for me now, on the way home from the dealer.

Both times it has happened, the car was idling, and I was out of the car for a short period. When I got back in the car, the error had appeared.

The dealer said if it occurs again (which it has), they will need to spend more time on it.

Do you have any advice that may help me and/or my dealer? Since it's both banks, I'm guessing possible causes might be fuel quality, fuel pump, or fuel filter. Does this sound right?

Vehicle: 2008 WM Caprice V8/A6, 180,000km.

Thanks,
Greg.

[toey]

Was the fuel filter changed at 160000km?

They are a intank filter and apparently cost around $500 to change by Holden :(

[skip100]

Thanks Toey - no, it was not replaced then and has never been replaced. I posed this to the dealer, and they said they've only ever bothered to change the filter when they've had to change a pump. They said it could be the filter, but it could also be the pump, or other things as well. They'll just need more time with it, unfortunately.

I'll book the car in again.

Greg.

[skip100]

This error kept coming and going. I decided to take it to my dyno tuner chap, and he found the problem literally in seconds - it was a leaky hose. (a vacuum hose I think - a short hose at the front of the engine). The hose was very brittle, too.

Greg.
p.s Note that my engine has not been dyno tuned. The reason I went to this place initially was simply to have my idle revs increased slightly, to ensure that my battery is not discharged under certain worse case conditions. They did this by re-programming the ECU. Holden could not do this.

[Slam3d]

Sounds like its too lean. P0171 and p0174 I would presume is being logged??? Does it have an aftermarket exhaust or intake???

[V8BEER]

I have had the same engine light come up on my adventra. Took it straight home and parked it up. Started up two hrs later and the sytem check came up ok. took for a 15min drive and the warning didnt come back on. i have now parked it in the garage until it gets serviced next friday and checked out. Mine has an OTR, full exhaust and mafless tune. No running issues at all before or after the light. :werd:

[skip100]

Sounds like its too lean. P0171 and p0174 I would presume is being logged??? Does it have an aftermarket exhaust or intake???

I haven't asked for the actual error codes yet, but the description was definitely related to "fuel trim". Car is completely stock except for a small increase in idle RPM. They reset the fuel trim and replaced the offending hose with a makeshift hose. They will check the fuel trim when I go back to have the proper hose fitted. The error hasn't reoccurred yet, but it's too soon to be sure it's fixed. (I'll be very surprised if it's not fixed)

Thanks,
Greg.

[skip100]

I have a bit more info. Apparently it was ADDING fuel, and it was adding up to about 25%. The tuner told me that when it hits 25%, it throws an error. The hose that failed was the PVC vacuum tube. He checked the trim after 5 days of driving with the repaired hose, and all is well. (and I now have a proper new hose)

I have lifter noise as well though. He said not to worry about it yet.

Greg.

[skip100]

(oops - I meant "PCV", not "PVC", of course)

[V8BEER]

had my car serviced today and they check for any fault codes - all good :yahoo: