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My Solstice says "hi everyone." Moving on.

I've had some really rough starting over the past month or so. I hadn't had time to really look at it until a few days ago, when I noticed the downstream O2 sensor harness had been cut, I'm assuming by some kind of road debris, though I'm not sure how.

Yesterday I replaced the sensor and harness connector (which had melted while hanging freely next to the turbo / exhaust manifold), and, lo and behold, my CEL disappeared and the car starts much more smoothly, though not perfect.

The other (possibly-related) problem is that, under WOT, the car hesitates to the point where it feels like a fuel cut. It's intermittent, but frequent.

While I was changing the sensor, I noticed that the gasket between the turbo and the exhaust manifold had blown. There's about a 2mm space between the turbo flange and the manifold on one corner, and a piece of the gasket is sticking out.

I've ordered a new gasket, planning to install it this weekend.

The Question

Can a large exhaust leak cause this sort of hesitation? It hesitates, surges, sounds really bad and I have to lift, then gradually accelerate to get it to stop. Not fun, a bit dangerous the first time it happened.

Cheers.

Update

It may be worth nothing that this just started a few days ago, before I changed the O2 sensor. I believe the car was running rich before that (makes sense as the ECU couldn't read anything from the downstream sensor), may have messed up the plugs. Too many things to check! Out comes the service manual, diagnostic section. :/

Update the 2nd

Unplugging the battery for half an hour re: @Paulster2's suggestion appears (so far) to have addressed the rough starting issue, but the weird hesitation at WOT is still happening. I haven't tried the tape yet. I did, however, notice that my AFR gauge is reading about 10.0-10.2 when it's happening, which is typical with this tune (though it seems a little excessive to me). That leaves air and spark. I'll check the plugs as they seem to be the most likely culprit.

Pᴀᴜʟsᴛᴇʀ2
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3Dave
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1 Answers1

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So, that's not what is generally meant by a "boost leak" – a boost leak is on the compressor side of the turbocharger, compressed air that should be going into the engine is leaking out before it gets there. What you have is an exhaust leak before the turbo charger.

That said, I don't think your exhaust leak would cause the behavior you're describing (but it should still be fixed promptly). The reason I think this is because I would expect the leak to possibly limit the boost pressure that can be obtained, but not to cause it to fluctuate. Depending on the volume of the leak it might not have any impact at all – especially at WOT. I think you could confirm (or deny) this with a quick and dirty test with some tape. It wouldn't even have to be heat resistant tape, I think you'd be able to tell before the tape burned off. Just wrap the joint tightly with several layers of tape and take it for a drive. That would either rule out the leak as the cause of the problem or prove me wrong.

dlu
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