dulahin89

Hi please help any suggestions.
I have a 2009 RX 350 150,000 miles,
Anyhow, I have misfire on cylinder #4 & #6 codes ok . So i swapped & labeled coils and ran good about 2 days then engine lights came on VSC and the tire traction. Changed coils and new spark plugs. Overheating now my husband changed the thermostat and the temperature switch also brand new radiator. Hoping all that would solve the problems. Guess what start her up ran fine a 2minutes then temp got hot again. There is no leak of coolant, no smoke out the tailpipe. Idle gets rough then calms down and runs fine then acts up again. I put super gasoline from Costco since i bought it in Nov. last yr. Any Ideas please.... I had 2 other Lexus 2002 430 no problems, a Lexus rx470 1998 for 6yrs no problems. I see tons of these on the road, I love the gas mileage whats wrong with mine??? I want to fix it.

numbafree

Hey there, welcome to club lexus. Sorry to hear the issues you are having.

To be clear, can you post the codes thrown for the cyl. misfires. and you did not get a code for the overheating issue, correct? With the overheating issue, you have a wandering or racing idle....

I have had misfires on other cars, and it's either been the spark plugs or the coilpacks. So you swapped out the coilpacks for cyl 4 and 6, correct? And when your hubby changed the spark plugs, what condition were they in? if you have a pic of the sparkies can you post it? thx.

for the overheating issue, its sounds like a bad sensor, since there's no leak, and you already changed the t stat.

either the sensor is reading it wrong, or the t stat isn't working, meaning it should fully open at 180 degrees to have the coolant circulate thru the engine block.

Last question, did your husband use all Lexus OEM parts? this is especially important for sensors.

lexus89A

Were you able to resolve this issue? I have the exact same problem that has been plaguing me for almost 2 months.

Misfire on cylinder 2 code, check engine light, vsc light, traction light and sporadic variable overheating (temp gauge going up almost to red and back down). My fans are spinning fine when overheating and I've checked the coolant it's got enough coolant.

Last time this happened I actually overheated and the radiator cracked. I had the radiator and temperature sensor replaced and did an entire coolant flush.

1 month later same issue started happening on and off. If I reset check engine light codes, car runs fine for 1 day or a week, and then the same issues happen.

I've recently replaced the spark plugs and ignition coils, car drives for a day or two and then same issues happen again.

I've researched the forums and a lot of people are having this problem but cannot find a fix.

lexus89A

So I fixed my issue by adding engine restore oil additive for compression that thickens the oil

my mechanic replaced thermostat spark plugs and fuel injector on the misfiring cylinder, but that did not resolve the issue. The misfiring cylinder had low compression.

he suggested there is a small leak somewhere in the head gasket that causes the overheating and misfire.

Added the $10 engine restore oil additive and after letting the car idle for 15 mins the issue was resolved

8000 miles later Lexus is running without a problem

$10 engine restore oil additive at NAPA or advanced auto parts

Margate330

I would hook up a scanner and see what temp your fans are kicking on and off.
If I remember it's 206F degrees.

On scanner viewing engine temp it should cycle consistently at the same temp over and over again.