i tried telling you guys... motor mounts fixed all of this
my idle still dips as with age it does normally... but i feel no vibrations.. it just seems the car isnt even running... try doing motor mounts!

 

okay motor mounts yeah yeah,,, so now the question is how much would it cost to take it to say a normal shop not a lexus overpriced shop and ask them to replace the motor mounts... how much for that + parts= total cost???

 

i'm nots ure anymore.. i think the mounts were like 70-90 each i forgot .. i may have the receipt sumwhere ill check.. labor depends on the mechanic.. i've seen 1-5 hrs of charge

 

An adequate mechanic should be able to do it in about 2-2.5 hours. However, most like to charge by the book, so it's about 3-4 hours.

But it's damn worth it!!

 

On my GS3 I have an misfire/idle shake


My idle shake/misfire is mainly when the engine is cold. This shake/misfire happens every 5 seconds or so. Under load hot/cold its perfect.

Anybody got any ideas?

 

yeah replace your spark plugs asap and clean out your fuel injectors tripple asap... have you been playing with your apexi neo thing???

 

I adjusted /changed nothing!

What did happen is I left the boot slightly open overnight and the light drained the battery. I jump started it and yes it was running a bit rough as the ECU needs to 're-calibrate' itself. 5 days and 200 miles later it drives great, but the rough idle is annoying.

 

sounds like a low battery issue.. see if you can take it to a shop to have the battery tested.. in the u.s. and japan a shop will hook the car up while running to a machine for a few minutes and see if the battery is receiving and putting out proper voltage or ampage or whatever to see if the alternator or battery is not functioning properly... i think its like $50 for this service, or you could just put in a new batter for like $60 out this way...

 

The battery is only 6 months old and I know its good. It can power my carPC & amps for 1hr and still able to crank.

My Apexi Neo has a voltmeter and it shows the correct alternator charging voltage

 

well since you said that your battery had been drained and needed to be jump started that is why i thought the battery might be the issue.. it still sounds like an idle issue then..

you said it shakes like every 5 seconds when cold, do the rpm's go up and down during this 5 second interval?? if so and the shake is when the idle is low, try resetting the ecu thing like suggested earlier.. does it shake when the ac is on as well?? is this all when in park "P" or when in drive "D" when your foot is on the brake and stopped...?

 

My cold idle was perfect this morning

Must have been something to do with the EGR valve not fully closed as yesterday I drove the crap out of it for a bit to 'assist' the ECU to recalibrate itself, so maybe I also cleared the EGR valve unintensionally

 

I tried the battery trick, wait more than 1/2 hour while changing the main driving belt. Changed the motor oil to full synthetic. Got slightly better now. 40% vs 50% shake when idling.

Next will be fuel injector clean. Just got a coupon from dealer for $129. Hopefully they will take out my oxygen sensor before doing it.

 

I'm interested in all this too. I've got an 01' GS430 with 75k on it. At a stop-light, it idles at 400 and the car vibrates and hums. If i put it in neutral or park, it idles at 700 and the vibration/hum disappear. If I turn on the AC, it will raise the idle as well to 700-800 and the vibration goes away. Replacing the motor mounts sounds expensive and unnecessary. But I'd rather do it right the 1st time than spend 100's on the wrong things.

 

i got exactly same car same problem like you have. I change my engine mount both in the front. problem solve . i just change it two weeks ago. you can check my latest post. trust me. 75k. teh engine mount is abosolute gone. our car has big heavy V8 engine.

 

Bad spark plug wire - Gs400/430's don't have spark plug wires, they are coil on plug.

Loose plug wire - As long as no one has gone under hood and loosened the 10mm coil bolt it isn't possible for them to be loose.

Faulty injector - If it was a bad injector you would know immediately by the strong smell of gas out the exhaust.

It could be a bad coil giving a weak spark but I would try to replace the plugs first. If you haven't done your plugs in a long time then the gap could be too large and will cause a rough idle.

Have you ever cleaned the throttle body? Another thing to check is if there is gunk buildup along the edge of the throttle "flap".

Low idle can happen after disconnecting the battery but should be gone within a short time of driving, if it remains after that then I would dismiss that as the issue.

You don't need to spend $129on having your fuel injectors cleaned, go to an auto parts store and buy the fuel injector cleaner made by Lucas. Purchase the big bottle and run it through every time you fill up the car for as long as it lasts (probably 5 or 6 full tanks) that will work just fine.

Also, while your at it, purchase some mass airflow sensor cleaning solution. Carefully remove the two 10mm bolts holding it on the intake and gently spray the element inside with the solution taking care not to touch the element with the spray nozzle, just the fluid.


Fwiw, the 400 and 430 are all aluminum V8's they are hardly any heavier than the inline 6 of the 300 as it has an iron block.