Lexus IS Forum banner
1 - 3 of 3 Posts

·
Registered
Joined
·
27 Posts
Discussion Starter · #1 ·
Well, it took almost 2 years to get another free weekend, but I’ve finally had a chance to do a compression test. When I pulled out the plugs, the first was dry, but the rest had oil in the well and the plugs were dripping in oil. Cylinder 5 was the worst followed by 6 and 4, 3, then 2. The results are:

1st 2nd 3rd 4th 5th 6th
Dry 180 205 205 200 195 195
Wet 183 203 200 200 195 200

at this point I don’t know a ton about compression test results, but what I’ve read points to the valves although I don’t know what’s causing the huge difference between cylinder 1 and the rest of them.

The reason for the test was the engine shakes at idle and gets worse under loads like the AC or when the vents are set to defrost. I’ve checked the MAF, replaced the engine and transmission mounts, and replaced the spark plugs and wires and valve cover gaskets. I had used Denso TT plugs but I’ve heard of issues caused by those so I swapped for Denso Iridium plugs. The plugs I removed were dripping with oil and there was a bit of oil in the wells. Compression test was the next step in diagnosing this shake.
 

·
Registered
Joined
·
455 Posts
So you could do what I just did that solved a similar problem. There's the off chance your Vacuum control valve set (something EGR related) has stopped functioning. I won't guarantee this solving your problem, but give it a go.

If you look on the intake plenum, in the back there is a small, about a 1/8" hose that goes into the intake. If you remove it, you will reveal a gold tinted cylindrical tube. That part of the intake will pull a vacuum. It stopped all my rough idling and misfiring and shaky engine problems immediately.

As for your compression test results, they look fine. Things start to go bad once you have greater than 10% variance cylinder to cylinder. Obviously, cylinder 1 is the highest concern. There is a chance the valve stem seals need to be replaced on it. Not that hard of a job if you're a semi-experienced tinkerer. Plenty of YouTube videos on it if you're curious.

Also, like Solar mentions, just update the original post you were discussing the issue in.
 

·
Moderator
Joined
·
4,791 Posts
Multiple posts are against the rules. It will not get you more help.
Engine Shakes at idle
 
1 - 3 of 3 Posts
Top