Barna6vi

I have an 02 GS300 with about 148k on it. The car isn't raced, it drives me around town and is very well maintained. About six months ago it started running really rough. Autozone said it had multiple misfires so I took it to my shop and they said it needed a tune up. Changed, plugs, wires, coil packs. Put good stuff back in. Reset codes and disconnected and reconnected battery. Ran like a CHAMP.

Fast forward to about 3 weeks ago. Car started running rough, same scenario. VSC lights, check engine light, idle all jacked up. Took it to get codes checked and it was multiple misfire again. Took it to the shop and they did a compression test (passed), swapped plugs around, wires around, coil packs around. It SEEMED to follow the coil swap. Changed the coil (new) AGAIN... still runs terribly. Checked the injectors, swapped them around... no change. It went from cylinder 3 (before coil moved) landed on cylinder 1 (added NEW coil pack). Now it says multiple when previously it was narrowed down to one. After new coil replaced it began to run fine and then when put in gear and under load started up again.

I have done everything I have read in all of the other posts (MAF clean, compression test, swap injectors, replace parts, disconnect battery, tighten battery connectors, etc etc) and I'm STILL at square one with a horribly running GS. I LOVE my car but I'm at my wits end! Does anyone have ANY ideas?

My car does have 20's on it and it also has a sound system (professionally installed). I don't know if that has anything to do with it, but I thought I would add it, especially since it seems electrical. I hate writing new posts when there is already SO much information on here, but I can't find anything else that comes after what I have already done. I really don't know what to do and don't want to get ripped off at the dealer for them to run tests and come up empty handed too. Has anyone seen anything like this before, a misfire problem so in depth?

Please help, even if it is off the wall ideas that you have heard in the past. I REALLY appreciate any and all guidance. Thank you, thank you in advance!!!

Alex

JamesBond1

Were there any other codes thrown with the misfiring ones?

You should check out your oil control valves and see if they work properly. One of mine went out on my gs4 a few months back and caused multiple misfires for me along with a flashing CEL, a VSC light and also a VSC OFF light. I believe, on your 300, that you have access to the OCV filters as opposed to mine which are internal - give those a clean.

SC4Paulo

iTrader: (2)

Don't rule out Fuel injectors, and or fuel pump.

Barna6vi

I read about OCV and I unplugged it and no change. Also, just misfire codes. Started off with multiple, narrowed it down to #3, swapped coil, so #1 coded and then swapped it out for a new one.

Injectors were swapped. And, will fuel pump cause misfires?

Thank you so much for responding!! I will look more into OCV and fuel pump I guess. Anything at this point!!

nmtsw20

This may sound odd but i have had random/multiple misfires code set on Rav4's, Avalon's and V6 Camry's mainly the 2GR motors. During the test drive the misfire count would be random for all the cylinders. The code was set because the tires were out of balance (rims had mud caked on the inside) the knock sensor was picking up the vibration and thinking it was coming from the motor. i remembered we swapped the wheels and tires from another car, drove it and the code went away.

Since you have 20's i know that there is usually issues when balancing,so it might be a possibility or you might want to check out you knock sensor.

NYGS300

Going thru the same issue with my 2000 GS300. Difference is I have misfires for ALL cylinders. I purchased a brand new OCV assembly hoping this will fix the issue, but then cracked open to check the sparks and they were filled with oil.

Have no idea how that happened, I'm thinking valve gasket leak. sigh.

troutman56

Must be something in the air as I am going through the same at this time. Misfire in cyl 1,3,5. I replaced the OCV and cleaned its filter to no avail. I also replaced spark plugs and the spark plug boot as well as an O2 sensor. NO luck yet. I am about to take it to the dealer as I doubt the coils are the problem and am lost after that.

offbad

iTrader: (5)

did you clean the throttle body?

SC4Paulo

iTrader: (2)

a weak fuel pump will pretty much fuel deprive a motor, generally speaking. not saying its that, just saying not to rule out a fuel pump

burny

When the coil packs fail or the igniter, a signal is sent to cut off the fuel flow and the car will shut down.

Barna6vi

After reading about the OCV not working, I am worried. I was JUST about to purchase one for $70, but thought I would check this thread again to see if there was any new info. I'd hate to spend the $70 and that NOT be it.

I also had oil in the spark plug areas. When this started I had multiple misfire codes too, but it was narrowed down. Now, I changed the coil pack for what I THOUGHT was the misfiring cylinder only to get MULTIPLE misfires again.

How do I check the fuel supply? How will I know it's the fuel pump? How do I change the signal to increase fuel flow? My car doesn't "shut off" it just runs horribly.

My car also has a pretty bad oil leak in the front of the motor too, it looks to be around the cam shaft seal area.

The wheels/tires probably aren't the issue, but I appreciate that thought. The tires are new and it was recently balanced and aligned.

This is literally driving the mechanic and I batty. I am borrowing a car for now but I need to get mine back up and running!

Barna6vi

I forgot to add.. the injectors and fuel supply to the motor have been checked and there was found to be no fuel issue. Plugs and wires were changed less than 6 months ago when the original coils were replaced. Ran FINE for about 5-6 months and out of no where it started running terribly with the lights on. As mentioned before, when the original tune up took place, there was small amounts of oil found in the spark plug areas. All of that was cleaned up. There were traces of oil found this time when top end was torn apart. Plugs were checked, nothing wrong with them. They were moved around as were plugs, no change. When coils were moved around it was thought to be narrowed down to one cylinder misfire. Coil changed... multiple misfires now.

My mechanic is basically saying that we are going to have to just start replacing parts, from cheapest to most expensive, starting with the OCV.

Is there a way to check and even make sure it is the OCV? I read you can unplug it and if you are still having the problem, it's a good place to start, I just don't want to spend the $70 if someone has a better way or idea.

Thank you all SO MUCH for your help already, I REALLY appreciate it!!

Alex

Mr Jokster

iTrader: (8)

Have you tried our new Lexus Team option?

https://www.clublexus.com/forums/gs-...uncements.html

GS300OC

Did you change the coilpack connector housings? This is a common issue. The plastic gets brittle and won't seat correctly. I just did mine and it runs like butta now.

burny

^This, you can get them off ebay