ANGRY BIRD

iTrader: (2)

Started as it got cooler in the morning, the colder it is on the cold start the worse it gets. As it warms it gets better, but still runs a little rough.

It is also accompanied by the MIL coming on and setting a P0300 (misfire) while idling cold. Then after driving it will usually set a P0171 and P0174 (lean bank 1 & 2). After the 4 consecutive trip of it running normal after that morning start the MIL clears. This happens everyday.

I thought it originally was a vacuum leak from a hole in the PCV hose but I repaired it, and tested the whole for a vacuum leak by spraying with brake clean. Yesterday I sprayed all around the intake etc while running for a vacuum leak, and did the same this morning when cold but found nothing.

My roommate is suggesting intake gaskets. Is this a common issue with the LS1?

97camaroguy

iTrader: (5)

Do yourself a favour put in a good set of plugs. If that helps report back.
I would also consider changing out your front two o2 sensors. I know that might get a little pricey but they could be due as well.

LS6427

iTrader: (2)

Get an OBDII scan on that thing......look at the 02 sensors while the engine is running and hot. Could be a bad MAF as well.....or dirty as hell.

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ANGRY BIRD

iTrader: (2)

The plugs and wires are new. TR55IX's and Taylor wires.

I've looked at it on a Tech II, O2S activity looks pretty normal. At that point it's running fairly good though, since I don't have access to it til I get to work. MAF Gps second looks right at idle as well. It's a bit high when it's been sitting a while and I start it, but that's because it's idling a little faster.

So try cleaning the MAF. I know my throttle plate good use a cleaning, but It's not so bad that it should cause it into a super lopey idle and want to stall out after starting.

Sometimes it does that, other times it's idling about 1000 RPM and sounds like it's missing it's *** off till the engine it self warms.

lt1pwr1

iTrader: (1)

I agree with the intake gaskets being bad. Yes, it is common on these cars. I don't see the O2's causing your issues as the car is in open loop until warmed up anyways. Something is causing both banks to go lean (intake gaskets are likely).

LilJayV10

iTrader: (39)

Have you checked if your ECT is showing the correct temp?

nascarnate326

iTrader: (1)

fuel pressure?

LS1Z28

iTrader: (18)

I had a similar problem with mine and it turned out to be a couple of weak coils. I replaced them all and the problem was resolved.