Hello everyone,

I am a member for a while but do not post so much since I am not very familiar with the the LS400 and how the things work and got all the info from the forums.

My car is a 1999 LS400 with 150k miles. I had a vibration issue in the engine after changing the mounts for engine and transmission and it was still there and comes at 1000-1200 rpms in gear or not in gear. I had a timing belt job done and replaced all seals and fluids and replaced the plugs also and my dad suspected bad ignition coils.

So I was checking mine on the passenger side of the engine and saw that their resistance across the outer terminals is 64-68k ohm and the left most point and second from the other side shows about 2k for almost all of them. I had the chance to check some other coils on another engine and their resistance was like 38k, 45k and similar random number. My left side bank coils read between 45k-55k. Now I searched google from any possible keyword to find a resistance range for the coils to check if they are bad or not and to my expectation I did not get a single result! I have been checking the forums also and did not get any. Did I search wrong or does the info simply does not exist? And the factory manual does not specify it either and does not even tell how to check it and I just tried testing with a multimeter and got these results.

So can anyone tell me what the resistance should be for the coils and if the coils are damaged can they cause vibration which is felt throughout the body from the passenger side till the drivers rear side and felt also at other rpms too.

Other thing I thought of was the part above the engine insulator which is the correct terminology as per the repair manual and normally known as mount. The part above is called the mounting bracket I presume but cannot seem to find the correct name and seen it as a vibration damper too. Can that be faulty and causing the vibration as I did not replace it and also are they available separately. There is also a weird noise coming from the right side when the weather is cold outside (more like under 20 degrees C) like a ticking or clicking and I replaced the power steering pump and alternator but it still exists. Also the valve cover gaskets and spark plug gaskets were also replaced as they were leaking oil previously. I am really baffled and confused and these are the only things coming in my mind. So does anyone have any ideas on this?

By the way I reside in the UAE and the car is imported from the US.

 

How about the spark plug wires and coil wires? If they're original 150K is about when they would start going bad. They can cause vibration, and arcing between the wire and other parts can make a 'snapping' sound if that's what you're hearing. If you take the covers off the wires and run the engine in the dark you can see any arcs coming from the wires.

 

In the 1998 there is a coil on each cylinder as can be seen in the page from the manual attached. Now there are no wires for the spark plugs at all besides the wires coming to the coil which I doubt are faulty as they are just ordinary wires present all over the car and just provide power to the coils which directly ignite the plugs. So no wires for plugs and if I have to change the coil wires how do I do as I checked with the dealership and they did not have them and said they do not need to be changed.