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Rough Ride

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have a 90 LS 400 with 119k miles on it. The other day I was on the highway then i floored it to get past this truck and a burst of endless smoke began coming out my tail pipes. I pulled over and let it idle. It was idling rough and the smoke continued to pour from the pipes, and even more when i hit the gas. It eventually stopped and I drove off. There was no difference in acceleration, did not lose any power at all. However, now it rides rough, like a mount is loose or something. My father and uncle are mechanics, but arent ASE certified, and both said it was just bad gas, and to only use BP gas. What do you guys think it could be?

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I remember when i first got my ls three years ago the people who had it would put regular in it i'm sure b/c the first couple of fill ups it would smoke just like you're saying when you would floor it, but it wouldn't be a trail just like a cloud. It doesnt smoke at all now, and i try to use fuel cleaner whenever possible.

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I remember when i first got my ls three years ago the people who had it would put regular in it i'm sure b/c the first couple of fill ups it would smoke just like you're saying when you would floor it, but it wouldn't be a trail just like a cloud. It doesnt smoke at all now, and i try to use fuel cleaner whenever possible.

Well the gas treatment only helped with the idle. It still rides rough, like a mount is loose or something. And if i floor it, for too long a trail of smoke will pour from the tailpipes

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Ugh, that sounds dreadful. Could be your coils going weak... I was told this when my LS was idling rough and had a gassy smell from the exhaust. Just a guess though.

Turned out I had unburned gas built up because I had only started the car for like 20 seconds and moved it one day when it was cold and apparently it had temporarily fouled the plugs... let it run for about 3 minutes then it was fine and has never happened again.

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Ugh, that sounds dreadful. Could be your coils going weak... I was told this when my LS was idling rough and had a gassy smell from the exhaust. Just a guess though.

Turned out I had unburned gas built up because I had only started the car for like 20 seconds and moved it one day when it was cold and apparently it had temporarily fouled the plugs... let it run for about 3 minutes then it was fine and has never happened again.

Well its been a few days, and it still happens, if i floor it at around 60-70, after a while there is a trail of smoke, loads of it. And the car rides terribly rough, like the drive shaft is going bad or something. But everyone I talk to says its just the car has been sitting waay too long and needs a big tune up. Took it to this mechanic shop and they said the same thing. I'm getting the tune up done today and I'll repost whether it helped or not.

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Ugh, that sounds dreadful. Could be your coils going weak... I was told this when my LS was idling rough and had a gassy smell from the exhaust. Just a guess though.

Turned out I had unburned gas built up because I had only started the car for like 20 seconds and moved it one day when it was cold and apparently it had temporarily fouled the plugs... let it run for about 3 minutes then it was fine and has never happened again.

Well its been a few days, and it still happens, if i floor it at around 60-70, after a while there is a trail of smoke, loads of it. And the car rides terribly rough, like the drive shaft is going bad or something. But everyone I talk to says its just the car has been sitting waay too long and needs a big tune up. Took it to this mechanic shop and they said the same thing. I'm getting the tune up done today and I'll repost whether it helped or not.

I'm not sure what a tune up is since the advent of electronic ignition and ECUs. There are no points. Timing is under ECU control. Newer cars don't even have rotors and distributor caps. In your case you have a couple of caps and rotors so if they are old maybe replacement is a good idea and perhaps plugs are well past useful life. Your performance seems pretty severe though so it suggests it might be a little more than these items. Good luck.

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A friend of mine had a similar problem and thought it was engine related but it turned out to be some type of inlet/outlet pipe dealing with the p/s system. Go figure! I would have that checked to be on the safe side. Wont hurt.

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A friend of mine had a similar problem and thought it was engine related but it turned out to be some type of inlet/outlet pipe dealing with the p/s system. Go figure! I would have that checked to be on the safe side. Wont hurt.

Well you were right, the tune up didnt help witht he rough ride. I'm thinking maybe it is the P/S system, cuz it is going out, or maybe i just need an alignment

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