jasone36

My high mileage 2002 SC430 seems to shake very slightly when I the car is idling at traffic lights (both when it is warm and when it is cold). The shaking is very very slight but it is noticeable. The shaking does not occur if the air conditioning is running or when the car is moving. The check engine light is not on.

The previous owner did mention that the alternator may need to be replaced eventually, but I don't know if this could be related.

If anyone has any ideas please chime in, thank you.

aquanuke

Maybe check the engine mounts

irokdastar

it can be a misfire . when was the last time you changed your plugs? also are you getting a check engine light?

jasone36

I have just purchased the car, so I don't know the last time the spark plugs were changed out. I am not getting the check engine light and I have hooked up my OBDII sensor to the car, the car is not showing any errors or messages.

Thanks

irokdastar

well ods are the plugs need to be changed so do that first . it can also be the igniter boot . one way to check is take out one plug at a time and start the engine. if you see good spark then your ok but if you get a faint spark or non at all try changing the plugs then the boot. or just take it to a mechanic and have him check it out and check the motor mounts as well.

aquanuke

Also try cleaning the maf and throttle bodies

VVTiBob

It's more than likely the motor mounts. But try this test. Get the car warmed up then drive on a regular surface street WITH the air conditioning running. Come to a stop and evaluate the level of vibration. Then do the same test with the air conditioning off. You will probably notice two differences. One lower RPM idle with the air off and more vibration. It that is the case it's the motor mounts. I experienced the same problem back in March of this year on my 02. Had the MM replaced (only had 57K) and it was back to not knowing the car was running with or without the air conditioning on.

Plugs are usually changed at 120k... have you checked the cars maintenance history at Lexus.com?

jasone36

VVTiBob, thanks for the detailed explanation. I will do the test you have described. I am the third owner of the car, the first owner had it from new until 120K miles and according to car maintenance online it seems it was regularly serviced, even had a "post 100K mile service". I would be more than happy to post the car history if you guys could help me decipher it. The second owner had drove it from ~120K to ~130K and only performed basic maintenance. I am the third owner.

VVTiBob, how much did you pay for your motor mounts to be replaced? Are there several of them, and did you have to replace all of them? Any information you provide would be very useful.

VVTiBob

I paid zero...covered under my extended warranty. Dealer billed warranty company $430 for one mount (parts and labor) There are two engine mounting brackets. If you do take the car into a dealer and develop a relationship, you can ask for a printed copy of the dealer maintenance records..It's a little less cryptic then the stuff on the web and has it all from the day born through current date IF the work was done at a lexus dealer AND they entered the record(s) into the nationwide database.

Yes

you can pull up your service history on lexus.com with your VIN. that will show if the previous owner had the scheduled maintenance done including the spark plugs. but i'm 98.2% sure it's your motor mounts. i had to have mine replaced around 50,000 miles. it's a common issue on the sc430.

Poqman

+1 I did this and really noticed an improvement in idle. It's cheap to do it. Search for posts on this subject for instructions.

Welcome to SC ownership.

jasone36

I actually did get my dealer to pull up the less-cryptic detailed dealer records (more info for each entry than online), but I do not believe the records state anything about "motor mounts" or "engine mounts" (I will check again), but it does list many generic services such as "75K service", "80K service", "100K Plus Service", etc.

You guys are convincing me that it may be the engine mounts... I may need to pick them up online (maybe from Sewell, if they're prices are good) and have my local $45/hr mechanic install them, I can't justify taking the car to the dealer with their $110/hr charges.

VVTiBob

Regarding service and mileage increments... if you look at your maintenance manual, either paper or the online version... you can see what the dealer took care of as part of the maintenance.

Here's a link to the mileage grid for maintenance: https://xws.xtime.com/xmmmenu/?varia...estimate=false Just click on the mileage tab near the top and slide over to the right for the higher mileage amount.

Yes

toyota usually charges about half as much. also, you can get a quote from them then ask lexus to match it. i did this for my timing belt and lexus came within $50 and i got a free loaner for the day.

VVTiBob

This is how mine looks for the engine mount replacement notation on my service history at lexus.com.

Dealer Reported 03/10/2011 56686 0****** ENG FRT MTG BKT &/OR INSLATR ONE SIDE