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SW03ES

Knocking & Smoke On Startup...

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Hey All...

Well I'm out of town and we've got the Lexus. I started it up today to move it back in the driveway so we'd have room to grill some food. It started very rough, knocking, pinging and blew a big puff of blue/grey smoke out the tailpipe. After maybe 15 seconds the idle smoothed out and the smoke went away. Shut the engine off and restarted...no issues. Let it sit for several hours and started it again...no issues. Took it for a short drive...no issues at all. That was nasty knocking too...sounded like the pistons were slapping right into the valves.

My cousin was out there when this happened and he says bad valve seals but I just don't buy that. Why did it only do it this time. No history of smoking, no oil use. Why would it have done this this morning and not yesterday morning when it had sat all night in the same spot? 145,000 miles...with the care its had WAY too early to think about any kind of valve seal degradation I think.

No elevation change. No weird or even out of town gas used. I remember this happening one other time too when we were out of town few years ago, when it started real hard and I had to give it some gas to get it going and it blew a puff of the same smoke. It was totally fine after that too. I remember this happening to my Dad's old 98 LS once too...he was as shocked as I was.

Any thoughts? Bad gas? Water in the gas line? Any truth to the idea of bad valve seals?

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Hey All...

Well I'm out of town and we've got the Lexus. I started it up today to move it back in the driveway so we'd have room to grill some food. It started very rough, knocking, pinging and blew a big puff of blue/grey smoke out the tailpipe. After maybe 15 seconds the idle smoothed out and the smoke went away. Shut the engine off and restarted...no issues. Let it sit for several hours and started it again...no issues. Took it for a short drive...no issues at all. That was nasty knocking too...sounded like the pistons were slapping right into the valves.

My cousin was out there when this happened and he says bad valve seals but I just don't buy that. Why did it only do it this time. No history of smoking, no oil use. Why would it have done this this morning and not yesterday morning when it had sat all night in the same spot? 145,000 miles...with the care its had WAY too early to think about any kind of valve seal degradation I think.

No elevation change. No weird or even out of town gas used. I remember this happening one other time too when we were out of town few years ago, when it started real hard and I had to give it some gas to get it going and it blew a puff of the same smoke. It was totally fine after that too. I remember this happening to my Dad's old 98 LS once too...he was as shocked as I was.

Any thoughts? Bad gas? Water in the gas line? Any truth to the idea of bad valve seals?

If this is a twice in a lifetime occurence, I wouldn't be too concerned. But knowing how fastidious you seem to be, and having the desire to be on top of things, this will likely eat away at your peace and quiet if you don't find out the cause. Before starting all sorts of tests you could do, see if there are any codes you can pull. Too early to say there's a ghost in the machine ... more likely cosmic rays!

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Had it been sitting on an incline before you started it? It may be a rear or forward stem seal weeping.

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Nope, level. Drove it home today and it ran fine.

Another thing I thought of, they were blowing leaves and pollen off the driveway that morning...I guess its possible something got blown up in there...

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Does not sound like bad valve stem seals, since it only happened the one time there is not much that you can do. I would suggest having the battery checked. A weak batters can cause unusual symptoms and some cars are more sensitive than others (my dodge ram being one of the worst that I have seen). I would also suggest seeing if there are any stored codes. Otherwise there is not much else you can do.

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I just replaced the battery about a month ago. I also had the emissions checked today as per MD law and it passed. I don't think it can pass with any codes stored...

Continues to run 100% normally. Weird.

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I would also assume they would not pass the car with any codes. It may possibly be a slightly dirty contact on one of the relays powering the ECM or fuel pump. Did you was the engine recently, or drove thru standing water? There could have been some water intrusion into a connector. Otherwise I would just wait untill you have further sypmtoms. I know that is not the most comfortable feeling, but it does not sound like there is a mechanical problem with the engine.

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Everything was dry. I had washed the car a couple days before but it had been driven on a trip in between and sat for a day...

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