thesmeazy

Hello,

A few days ago my "Check VSC" warning came on along with the check engine and traction lights being on. I left my car in a parking garage for a week when I was on vacation and the lights came on once I started the car after getting back from my trip.

I have had the "Check VSC" warning before and I fixed it by replacing my gas cap. My gas cap seems fine this time around so I got my codes scanned and the only one that came up was P0300.

Has anyone else has this issue with the 2007 Lexus GS 350? I still feel like it's my gas cap because I bought a cheap replacement last time around.

What do you guys think?

Thanks In Advance,
Sam

burteboy

p0300 is random multiple misfire. you need to check which cylinder is misfiring. could be a ignition coil

thesmeazy

Oh I see. How would I go about investigating that?

Othic

Just clear it and go beat the hell out of the car. Its probably a little carbon build up. Fuel cap has nothing to do with misfires

burteboy

have a technician scan the vehicle and read the freeze frame data it should show the cylinder or cylinders misfiring.Did this condition happen after filling up ? if so it could be some bad gas.Note do NOT driver the car hard thinking it would correct it self, doing that could damage your cat. by the way MR Meazy im looking for a GS 2004 2005 pearlwhite loaded. thanks. let me know if you need any more advice.

burteboy

Advice when filling up stop when the nozzle clicks. adding more fuel could cause fuel to get in the evap system which could cause the vehicle to stall or misfire.

thesmeazy

Update:

I've tested each cylinder by uplugging it and listening to the rpm but all of them seem to be firing correctly.

I also sprayed some water to see if I could hear some vacuum leaks but all seemed fine.

Could this be the spark plugs? The error code is random misfire P0300.

SILENTM

Take it up to redline a couple times to see if it sets a misfire to a specific cylinder, putting load on the engine will test the ignition system, I.E. spark plugs and coils. Gas cap will not set a misfire code. if your only getting random misfire codes with no performance issue, could be carbon build up as mentioned earlier

etomas6

The Gs350 doesn't usually suffer from carbon issues because the port injection help wash the back of the intake valves that typically get carbon build up in typical GDI systems (is250, gs300 ect). But it is possible. If its just a p0300, its very random and not regular misfire. The car can detect misfires but when it codes a 300 only its too irregular to pin point which cylinder is misfiring, and can only detect slight to moderate misfires or variances from crank pos to cam pos.
if your car is higher millage and you have never had a tune up performed in your owner ship, I would pull one of the coil packs and take a peak at the top of the plug. If you see a p, cross or other marking, if there is they are plugs from the factory and I would go ahead and start there. If its just a cylinder misfire code and no others, its hard to diagnose properly without visually looking at the data list, and try and verify if its a mechanical issue or something else. I have seen faulty injectors cause misfire but that would be cylinder dependent, the same goes for a coil pack. (coil packs also typically set their own trouble code, but not always.)

kanondu

Hello guys

Mine is rx 350 07 model. I have been using it for two years now no problem. recently I noticed that it doesn't move well at a certain speed. especially when I want to move with full force, the vehicle will be stalling as if it want to off but if I press the gas pedal gently, it will move fine. The funny thing is that at idle mode the engine steams very well without jerking safe in few occasion when I start it in the morning, it will jerk for some seconds and return normal.

I have clean the air filter severally and recently the check engine light came up and started flashing. I stopped the car and quickly diagnosed it with my obd scanner and error code P0300 came up and indicated random multiple cylinder misfire.

Any help on what to do will be highly appreciated.
Thanks

HewittTech

Random misfires are some of the worst to try and diagnose but it has nothing to do with a gas cap. It can be anything from simply having bad gas to an engine temperature sensor reading wrong. First run the tank to empty and fill up with high quality fuel of at least the minimum octane in your owners manual. Then some really good fuel injector treatment or some canned heat (to get water out of the fuel) especially if you buy low quality gas. Replace the air filter and clean the MAF sensor TB.
The standard tune up items will usually take care of it. With higher mileage vehicles you also start to look at things like 02 sensors and spark plugs needing to be replaced as well as starting to investigate and replace any cracking or loose vacuum lines.
If none of that takes care of it it is time to move on to more serious diagnostic measures.

Vooduguru

In my spark plug change, I took some carb/TB Injector cleaner and cleaned out the moderate amount of carbon buildup in the TB. Got it all cleaned out, now I have a CHECK VSC light on, the CEL, and the TRAC light on. Will driving it around clear it or do I need to get an OBDII tool to clear it?

**Update**

Drove the **** out of it for a few minutes, cycled the ignition, CEL cleared itself out. Yay

adgsf

I have a 2002 gs300 I just got it back from the dealership they replaced 02 sensors I filled up drove around town then drove 2 hours and around 1:45 min the vsc vsc off and check engine light came on and took it to a auto zone to scan and said p0300 just spent 1000 could u point me in the right direction do I just have to change the ignition coils ? Or spark plugs or distributer cap/rotor