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My 1999 Lexus Es300 Is Driving Me Crazy! Anyone Been Able To Deter


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Ok, here's my story...

I bought my car March 2013 with 165K miles.

Since then I drove it 17K miles... mostly highway.

When I first got it I realized it needed to warm up before it would shift into 3rd and then into OD. So I always let it warm up before getting on the road and it was never an issue. A couple over times over the last 5 months I noticed that when I'd start it after it had sat for about an hour, it would not idle properly. I would shut it off then restart it and it ran perfectly.

About 7 weeks ago I made a quick stop and jumped back in and it was completely dead. Turned out the neg battery terminal was loose, and it started right up. During that time I noticed a little miss when driving from time to time. But it was barely noticable. Then about 5 weeks ago it began running rough. As long as I kept the gas on it was okay but the moment I took my foot off the gas it started running rough again. I took it to a local cottman transmission where I know the mechanic. He looked at it and said the sensors indicated it was clogged catalytic converters. He took the exhaust down and discover the catalytic converters had been hollowed out. Apparently the previous owner's mechanic did it. But I drove the car for 17K miles without cats so that wasn't the problem. Cottman ran diagnostics, replaced the plugs which were fouled saying that was the problem.

I drove the car and within 4 miles it started having the same running rough problem. I decided to get it home which is about 60 miles and it really ran rough with the CEL starting to blink a couple miles from home. But it stopped blinking when I stepped on the gas. The next day I drove it 20 miles to a mechanic who is a friend. He had the car for 3 weeks, ran diagnostics, checked the timing, removing sluge from the valves and thought on 2 occasions he thought he fixed the problem until test driving it several miles and it would start running rough again. He checked the cylinder compression and told me the back ones were puting out about 80 psi while the front ones were at 120 psi and that had to be the problem. Said it would cost $1500 to fix but that might not even work because of the ollowed out cats. He said the last owner may have put oil additives in the engine as a temporary fix. But it ran beautifully for 17K miles. He suggested I get rid of the car. So I drove the car home and it really ran rough and didn't shift into OD.

I picked up M1 Mobil synthetic oil and ring compression fix additive and changed the oil, filter and added the additive and put 93 Octane gas with fuel injector cleaner in the tank. I drove it 65 miles on a highway to work and with the exception of a couple misses it ran great. On the way home i got caught in traffic and it ran really rough and the trans continually would shift out of third and back into third gear. CEL would blink and stop randomly but mostly when I was at a slower speed.

I read the cause could be the IACV so I removed it, cleaned it with CRC and reinstalled. Today I drove it 15 miles and it ran beautifully. I made a stop for 15 mins, jumped back in and noticed it wasn't going into OD. Made a couple more stops before driving home. With the exception of no OD it ran fine until I stopped at my driveway, put it in reverse and it started running rough again. I turned it off, waited a minute and started it, drove around the block and the running rough and high idling happening. The CEL was not blinking but I can only think it wouId have if I continued to drive the car. I started to think this is a computer problem. I should mention the CEL lit up 150 miles after I bought the car.

I would love to know if anybody has any idea what is going on!! Sorry for the long story!

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Too much wrong for my pea brain, I would part it out, or trade in at Lexus, the service manager gets something for bringing a potential sale to the sales manager,service manager has incentive to repair your car cheaply, so they can re sell. A terrible trick to play on a dealership is in the sates with 72 hour laws, I guess for impulse buyers, unwind your trade deal after they fix your car. LOL It happens everyday in the car business. It appears no ones answered your post because of all the problems, too complex with the cats missing, and has been sending signals wrong, Ive heard those cats are very important and cant be removed or altered to make smoothe flo thru thus more horsepower, I wander why no lights came on, or did it come on and you turned it off? Ive been wanting to do some engine work and add another 20 or 30 hp with dual turbo charger,whatever kind of headers w cats there are,if any, some kind of cold air induction, or maybe a computer chip. But it doesn't seem possible because of the cats. Ive asked several auto mechanic people how to increase hp, and they don't know. It appears someone tried with your car, and maybe they had the set up, then took it off before selling to you.

Good Luck to ya, Im looking forward to hearing you got it fixed and about the cats,



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  • 2 weeks later...


I have a 2000 ES and it sounds very similar to the problems I was having with mine recently. It almost drove me stir crazy. Any time you have a Check Engine Light (CEL), take it to your local auto parts store and have them do a diagnostic. That will at least point you in the right direction. I was getting multiple mis-fires. Also, it would operate perfectly, then 2 seconds later I felt as if I were in a 40 year old rusted out dump truck. Normally when the CEL comes on, the car will put itself in "LIMP" mode and is easily recognized because it will not go into OD, and you feel the car jerk to speed up and slow down, and really doesn't seem to want to maintain constant speed.

The multiple mis-fires ( in my situation ) led me to the Oil Control Valves... and their screens. There is one screen and valve for each bank of the engine. I have both cleaned and replaced the OCV and screen on both banks, only to have the dump truck show up again. After ruling out most of the associated error codes and based on it happening after the engine is warm I just felt it was something in the oil pan.

I drained the oil, and removed the oil pan. I found debris in the screen of the oil pick up. And it makes sense because the car would be running bad.... if I had to make a stop on the way home and I killed the engine, at times it would start and run normally again for a few minutes before the problems returned.

So I cleaned the oil pan, new gasket and put it back on, then I removed both OCV's and screens and cleaned them..... It fixed my problem.......... (for a year). Since it can't draw enough oil into the motor to operate the Oil Control Valves, it jacks with the timing, this causing the misfires. I just did that again recently. But it is certainly worth it. It doesn't take long for me to get frustrated when it is in dump truck mode. :)

After 14 years, my car had gotten to the point it didn't idle very smoothly like new. It also would not "idle up" on cold start as it should until the engine warms. There is a kick-!Removed! post by GoldenStateSilverSport detailing cleaning the IACV.. He is my hero. I forgot how nicely it ran.

Hope this helps! Please let me know.

https://db.tt/StHBnDyi This is a link to a photo I took of the intake screen located in the oil pan.

And for the record.... I've had my car since it was new. I am fairly rough on my vehicles. I have over 200k miles on my car and I really didn't have any "repairs" outside the normal maintenance items until about 2 years ago. It's showing it's age and it's wear and tear, but I still enjoy it and trust it. I can't say I agree with the other suggestions to scrap your car. If it has all of it's maintenance documentation, this is likely to be a hiccup in the overall scheme of things.

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