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Discussion Starter #1
Alright. Obligatory "I'm new to this forum, the IS platform, imports in general, etc etc aside, I just picked up a 2002 IS300 5spd a couple weeks ago and it has a constant, steady, shake at idle. Under A/C load, it gets much worse and shakes the entire car pretty aggressively. It smooths out almost completely once you use the throttle at all, and it will stay smooth until about 15 seconds after you get to a stop or to a certain low enough speed (if for example you're coasting it out to a light and get down below 20 with the clutch in). No codes, pending or otherwise. No surging or rpm change while it happens. The rpms kick up a bit with the A/C on (as they should). And there isn't any surging while cruising like what you'd expect with bad plugs or wires. No pings or knocks. I've seen a couple people with similar issues on this forum and others, but they usually describe a surging rough idle. This is just a constant side to side vibration at idle. So, things I've replaced or cleaned:

Oil and filter
Spark plugs and wires
Valve cover gaskets
Cleaned the ocv filter
Motor mounts were done. Transmission mount looks good.

The car was stored for about a year with scheduled start ups and drives by the previous owner. The battery was charged before I took ownership and the alternator tested good. The shake continues.

I found that if the car is revved when stopped, the engine will smooth out and then as soon as you let go of the gas, it shakes hard coming down the rpm band, and then goes into the constant shake when the rpms bottom out at 750ish. Anybody have suggestions? I've tried pretty much everything I've seen on these other posts before coming here (aside from sacrificing a chicken) but I'm now at about the extent of my troubleshooting knowledge. Any help would be appreciated.
 

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Alright. Obligatory "I'm new to this forum, the IS platform, imports in general, etc etc aside, I just picked up a 2002 IS300 5spd a couple weeks ago and it has a constant, steady, shake at idle. Under A/C load, it gets much worse and shakes the entire car pretty aggressively. It smooths out almost completely once you use the throttle at all, and it will stay smooth until about 15 seconds after you get to a stop or to a certain low enough speed (if for example you're coasting it out to a light and get down below 20 with the clutch in). No codes, pending or otherwise. No surging or rpm change while it happens. The rpms kick up a bit with the A/C on (as they should). And there isn't any surging while cruising like what you'd expect with bad plugs or wires. No pings or knocks. I've seen a couple people with similar issues on this forum and others, but they usually describe a surging rough idle. This is just a constant side to side vibration at idle. So, things I've replaced or cleaned:

Oil and filter
Spark plugs and wires
Valve cover gaskets
Cleaned the ocv filter
Motor mounts were done. Transmission mount looks good.

The car was stored for about a year with scheduled start ups and drives by the previous owner. The battery was charged before I took ownership and the alternator tested good. The shake continues.

I found that if the car is revved when stopped, the engine will smooth out and then as soon as you let go of the gas, it shakes hard coming down the rpm band, and then goes into the constant shake when the rpms bottom out at 750ish. Anybody have suggestions? I've tried pretty much everything I've seen on these other posts before coming here (aside from sacrificing a chicken) but I'm now at about the extent of my troubleshooting knowledge. Any help would be appreciated.
Do a compression test. May have a burnt valve or bent valve.
 

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Alright. Obligatory "I'm new to this forum, the IS platform, imports in general, etc etc aside, I just picked up a 2002 IS300 5spd a couple weeks ago and it has a constant, steady, shake at idle. Under A/C load, it gets much worse and shakes the entire car pretty aggressively. It smooths out almost completely once you use the throttle at all, and it will stay smooth until about 15 seconds after you get to a stop or to a certain low enough speed (if for example you're coasting it out to a light and get down below 20 with the clutch in). No codes, pending or otherwise. No surging or rpm change while it happens. The rpms kick up a bit with the A/C on (as they should). And there isn't any surging while cruising like what you'd expect with bad plugs or wires. No pings or knocks. I've seen a couple people with similar issues on this forum and others, but they usually describe a surging rough idle. This is just a constant side to side vibration at idle. So, things I've replaced or cleaned:

Oil and filter
Spark plugs and wires
Valve cover gaskets
Cleaned the ocv filter
Motor mounts were done. Transmission mount looks good.

The car was stored for about a year with scheduled start ups and drives by the previous owner. The battery was charged before I took ownership and the alternator tested good. The shake continues.

I found that if the car is revved when stopped, the engine will smooth out and then as soon as you let go of the gas, it shakes hard coming down the rpm band, and then goes into the constant shake when the rpms bottom out at 750ish. Anybody have suggestions? I've tried pretty much everything I've seen on these other posts before coming here (aside from sacrificing a chicken) but I'm now at about the extent of my troubleshooting knowledge. Any help would be appreciated.
Have you cleaned your MAF? and also have you tried resetting your ecu?
 

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Discussion Starter #4
Do a compression test. May have a burnt valve or bent valve.
I'll have to wait till I get another free weekend to try that out. Really hoping that's not it. If it's at that point, I may as well just start my rebuild with GTE internals early.


Have you cleaned your MAF? and also have you tried resetting your ecu?
I haven't had a chance to look at the MAF yet. I'll have to try it. Probably should have tried it first lol. I'll give it a clean and see how that goes. Haven't reset the ECU at all. I'll have to see if I can find a guide for that. Unless it just requires disconnecting the battery lol.

Thanks for the suggestions though, guys. I appreciate the help. I'd love to see this car run for a long time.
 

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I'll have to wait till I get another free weekend to try that out. Really hoping that's not it. If it's at that point, I may as well just start my rebuild with GTE internals early.




I haven't had a chance to look at the MAF yet. I'll have to try it. Probably should have tried it first lol. I'll give it a clean and see how that goes. Haven't reset the ECU at all. I'll have to see if I can find a guide for that. Unless it just requires disconnecting the battery lol.

Thanks for the suggestions though, guys. I appreciate the help. I'd love to see this car run for a long time.
Yeah I'd rule out the easy stuff first. Get some MAF cleaner at your nearest auto parts store, unplug your MAF by removing 2 or 4 screws on your intake(i forget lol), give it a spray then reset your ECU by unplugging the battery for about 30 secs to give your ECU a chance to learn the A/F ratio. Good luck!
 
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