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06 3.5 having serious issues, please help

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  • 06 3.5 having serious issues, please help

    Hi, I really hope someone here can help me out, I've posted on other forums with no replies and have read at least 500 different threads over the last week.

    So I'll start here...I bought an 06 g6 gt 3.5 lx9 from a family friend about 2 mo ago. I knew it had never been serviced and they lived on a dirt road. Has roughly 130k on it.
    When I got it right off the bat I knew motor mounts, struts, end links, rotors and pads, and steering shaft were all shot within 2 minutes of driving it.
    So began replacing everything and about a week in I decided to pull the tb and clean it as well as the maf because idle was rough, bouncing between 720-930rpms.
    The tb was filthy, egr port was completely clogged on the intake, throttle plate was resting at 26% according to my scan tool because of so much carbon.
    Well after cleaning it all, I didnt notice any difference!

    So I ran a bottle of b12 through the gas to clean the injectors and about a 1/8th way through the tank of gas it began running very rough and loud.
    So I checked it out on the torque app and my ltft on both banks was all over the place...no ryhme or reason, bank 1 -21, bank 2 12, then without changing a thing it would go to bank 1 +6 bank 2 -14, and that was at idle, driving, whatever.
    Everything else looked ok, o2 sensors looked to be working fine, all tests passed, load was fine, etc...but I did notice on the test results cylinder 6 misfire 19 times...so checked it out many times under different circumstances and would get 0, 12, 9, 128, 36, 2...didn't matter what the laod.
    So began troubleshooting. Checked wires, GOOD, coil pack, GOOD, ...plugs, not great but GOOD, so I'm left with injector or wiring.
    So figured since i had to pull everything to get to the injectors I might as well go all out.
    So I removed everything down to the head, cleaned everything spotless, installed new lower intake gasket, valve cover gaskets, injectors, plugs, wires, coil pack, all o rings and gaskets for heater lines, new hose clamps, everything.
    Get it all back together and fire her up only to hear a loud vac leak at inj 6 so had to pull it all back out throwing 150 bucks worth of gaskets down the drain!
    Turns out 4 of 6 orings to the manifold had torn and pieces ripped off and went into the valves.
    Ebay seller sold me busted junk!
    So now I notice looking through inj holes at the valves they are nasty and the orings gunked em up.
    Also saw what I thought was a gasket leak.
    So did a compression tesr, results are #1-170, #2-168, #3-120, #4-168, #5-152, #6-160....all were good except 3. It was 110 I put some oil in it and went to 120ish.
    Figured it'd be fine.
    Checked coolant pressure and it held fine at 15psi.
    So I went ahead and put it all back in.
    Now I have to prime it 3 times before it will start, when it is running it feels way better but still not right.
    No vac leaks, fresh oil and coolant change, new cold air intake and filter, yet when I check out the live data I'm now at -10 to -18 for both banks long term fuel trim.
    It goes up when I gas it but goes right back down at idle.
    In the test results it now shows 3 to 10 misfires on 1,2,3,5, 6 cylinders.
    I have checked everything I know of and can't figure this out....why would it be running so rich?
    I know injectors aren't leaking, fuel pressure is obviously low (new fuel line must have a leak) so the regulator couldn't be an issue, idk.
    I have a few things I know are issues but not sure if they'd cause it.
    First off I have bad exhaust leaks...like 5 of them but they r all post cat so didn't figure it would cause it.
    The plugs I got ac delco iridium 40 101 were suppose to be pre gapped to .06 but they all were different so I gapped them without touching the tip but possibly could be an issue.
    The fuel line not holding pressure, could that cause it? What about possibility of clogged cats or o2 sensor, map, etc....I also get slight white smoke out of exhaust, not coolant and doesn't smell rich so idk, it goes away then comes back, not bad though for cold weather and humid.
    Anyways, just could use some advice. Sorry bout the rant just wanted all the details out there

  • #2
    Re: 06 3.5 having serious issues, please help

    Since this is your most updated post I'll see if I can help here. So much going on it's hard to wrap my head around.

    Is there a test port on the fuel rail you can connect a fuel pressure gauge to? I'd monitor fuel pressure at startup, while running, after shut down. Pressure leaking down after shutoff is usually indicative of a stuck injector or leak.

    Correct me if I'm wrong, but I believe your G6 has a returnless fuel system, which means the pump is regulating the pressure, perhaps you have a weak fuel pump. But that doesn't explain the rich fuel trims.

    It wouldn't hurt to check the O2 sensor, specifically the connector, check for corrosion. Since you mention the trims look perfect at times perhaps there's a intermittent connection issue.

    The misfire on #6 in the mix just adds to the confusion.

    After all the work and adjustments you made, are there any codes coming up? Even after clearing them does anything else come up at all?

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