sajawalas

hi all. my car starts shaking in lower rpms i.e. if my car is on 80km/h and car is in 8th gear (lowest Rpm) it will start shaking unless i leave accelerator or press it even more to increase rpm then it goes normal. this only happens if my car is in lower revs i.e below 1400 revs (1.4). i tried to change the 4 tires, wheel balancing, i checked the rims and fixed them from the RIM repair shop. any other clue ? as per my mechanic all mechanical things are fine. any clue what could be the reason ?

Tec80

Likely is a misfire, but that should set a check engine light. If there is no check engine light, see if you can make it shake for as long as safely possible, if it is a misfire that will log a code.

Otherwise, it could be a faulty injector. You might try 2 bottles of Techron in the tank, and/or a different brand of fuel.

sajawalas

Dear Tech80. thanks for your suggestion. there is a check engine light and the log codes are for O2 sensors. do you think O2 sensors are the cause ? fuel injectors i've checked recently from my dealer and replaced 3 out of 16. rest are fine. they cleaned the injectors and i replaced the spark plugs as well. if you say this O2 sensors are the cause, i will replace them today.

213374U

Sounds like a worn engine mount to me

yyymmm31

--
Which model year do you have and how many miles on the car? Your profile says that you have a LS430. If so, perhaps folks on the LS430 forum can provide you more helpful suggestions. Regardless of the model year, before you replace anything, check if you have trouble codes or not. If there are no trouble codes, it is most likely a mechanical issue such as a worn engine mount or worn suspension part. If there are trouble codes, replace or repair the necessary parts as the trouble codes indicated.
--

Nospinzone

Yes, I was thinking the same thing, a loose or broken engine mount.

sajawalas

i've replaced the engine mounts. 2 engine mounts + Gear Mount + 2 rear differential mounts. problem is still the same.

sajawalas

i previously had LS430 2004 but recently i bought it before 2 months and i discovered this issue and i tried to visit all the dealers but the problem is still the same even after spending so much amounts thats why i decided to took experts suggestion by putting in club lexus

UDel

Have you tried changing spark plugs and do a fuel injection cleaning, normally with those issues it shakes or idle is rough when the car is not moving but it may do it at speed if it is really bad. Are you sure your tires are balanced, if they are not balanced or a weight fell off the tire the car will shake at certain speeds.

sajawalas

yes dear i've replaced the spark plugs also and cleaned the 16 fuel injectors as well. i found 3 of them were not performing well and i replaced these 3. i replaced the 4 tires and i did wheel balancing as well. also i changed the drive shaft bearing and rubbers but still the issue is same.

Nospinzone

213374U

Is this an AWD or RWD model?

BMW7_LS430

Post all the codes you are getting and any code history. Best to get OBDII adapter and app like Torque Lite or buy pro version.