JBls400

Ok so I bought this 91 ls400 used for a more than fair price, he advised me that it needed power steering work and smoked a little bit when first started, I got the car and drive it for about a week occasionally putting in PS fluid as needed. Now this morning it is running rough and has kind of a loping idle (like a big cam in a drag car) and the loping is present when accelerating and coming to complete stop, vibrates at speed under acceleration only. Definitely is missing out. Oil is clean and no pinging or knocking, slight valve chatter but very slight. Seems to have 90% of power and is not stalling when idling. Please help its my first Lexus and first problems. I was thinking valve seals are bad and could have fouled out plug/s? Any help would be greatly appreciated.

steve2006

You need to diagnose a bit more, driver's side coil pack is a common fail but there are other causes, leads,plugs etc.
Pull each coil lead out of the distibutor cap in turn and see if there is any difference, if the misfire stays the same when one of the leads is unplugged that's where you are missing a spark, if the engine won't fire at all it's the other coil that's faulty.
Another clue is glowing cats after a run with misfiring.

JBls400

Thank you, this is my first ls400 and I plan on keeping it or one like it from now on, I will check coils, cats like advised, I've also read the power steering bible thread and am wondering if I'm getting PS fluid in the vacuum lines. It was running great had minor vibration during acceleration but thought maybe mounts(engine/trans) because it vibrated some when in gear and stopped. In reflection the tiny tiny vibration during normal acceleration before the problem I think maybe that was a tiny miss and has jus gotten worse. I don't know if my symptoms are real bad or sounds simple to a seasoned ls400 owner. Thanks for ANY help!! P.S. has high miles. Thanks.


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JBls400

Found the fouled plug and replaced, running 110% better, I broke 2 vacuum lines and don't know what they are, both are coming up front behind the PS pump, one went to plastic intake and one to very front of intake plenum. Wondering what vacuum lines they are. I blocked them off for now and runs great. If anyone could tell me what the lines go to I would greatly appreciate it. Thanks.



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RA40

iTrader: (6)

I broke that fitting recently. My buddy's tell me that on old vacuum lines that don't come off easily, just to cut them. There is usually enough hose that losing an inch isn't a big deal. I bought replacement hoses so that the next round they will be easier to remove.

https://www.clublexus.com/forums/ls4...e-fitting.html

JBls400

The two lines I broke have power steering fluid coming out of them and obviously the fluid was going into my motor(found my power steering leak lol.., it used to smoke some on start up, now 0 smoke what's so ever. Is there a easy way to block these lines or should I get new pump and reconnect the lines? Thanks!


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