Hi everyone

Hoping someone can help me out I have a 2008 Lexus GS350 RWD. I recently did a custom exhaust axle back system. When the car is cold when driving the rpm goes all over the place when u let go of the gas. As soon as the car gets to normal temperature it goes back to normal. I live in Canada so it does get cold here. Anyone know what would be the issue?

 

Hi, I am experiencing same issue. Mileage on '08 GS350 AWD is 198,000kms. I too live in Canada and it especially does that when heater fan is engaged.
Once car reaches normal operating temperature it settles down. When cold it will rev higher upto 900 rpms and brake pedal needs to be held firmer when sitting at a Red Light

 

so I managed to fix the issue on my specific setup, I forced the ECU to relearn by unplugging the battery for 30 mins or so. It stopped revving up and down when cold however RPM being high when cold is normal on this vehicle as it tries to warm it self this car does not like the Cold. This is my 2nd GS and both of them had the same issue.

 

Thanks ACE
Seeing you have similar year and model, have you ever had car not start on you....Start button light orange, battery tested fine so did FOB.
I depress pedal and brakes light come on so not brake switch, dash just flickers once then goes dark. Doesn't even go to ACC mode.

Do you think unplugging battery would reset that??
Not sure if Immobilzer is activated

 

Never had that problem with mine. It sounds like an electric problem. My suggestion would be start with the battery just for testing purposes borrow or see if u can get another battery installed and test it out if the same issue occurs it might be your starter have that tested and go from there

 

I had a similar intermittent issue with my GS350 and I replaced the battery in the key fob.
That fixed my issue.
t's a cheap little batter and easy to change.
Try that.

 

Both of my FOBs have good batteries tested voltage they are fine.

 

So issue found....Power Source Control module under passenger glove box gets damp especially when left overnight outside.
small space heater on passenger floor for 4 minutes to warm up the area and its starts right away no issues.
Need to access this unit to check for moisture in the area that must be recurring. Any ideas how to remove a glove box properly on 2010 GS350?