mdpresco

Our 98 ES300 has 175,000 miles. At around 45-50 mph it has what I think is an ignition misfire. Plugs and wires have been replaced. Replaced the boots on the coils also. There are no codes showing. It only "skips" when holding a steady speed. Accelerate and it doesn't stumble. It idles smoothly. Could it be a torque converter lock-up issue where the trans can't decide what to do? (I haven't seen this in the forums.)

Rather than start changing parts, what should I try next? Coils and injectors seem to be the only things left. Is ther an easy way to troubleshoot?

jltait

If I had to guess it sounds like your fuel injectors could use a good cleaning. The fact that you were only experiencing hesitation at that speed could be coincidental. Doesn't smell like a transmission issue to me if there is no attendant "jerkiness" or the issue doesn't always occur between gear changes.

Clean your throttle body too just for good measure and make sure your air filter is clean. Can't hurt. If you've ruled out a spark problem, the only places left to look are air and fuel.

mdpresco

I can clean the throttle body. Should the dealer do an an injection service or would you take it to a local shop that does it?

jltait

I would go to a local shop. No reason to spend dealer prices for something so routine as a fuel system inspection and or cleaning. From what I've read, another potential cause for an engine miss is a partially clogged fuel filter. You may want them to take a look at that too.

I'm not advising the spending of your hard earned dollars. Just a shade tree mechanic sharing his instincts.

Good luck.

mdpresco

Thanks for the reply. The fuel filter was recently changed and the air filter is almost new.

There is a shop that specializes in German cars that I used years ago when I had a MB. They are reputable and may cost the same as the local Toyota dealer. I'm looking at $100+ which I will gladly pay if I get the problem fixed the first time.

mdpresco

Well, it has been over a year. We replaced the coils still thinking it was an ignition problem. It wasn't.

Today the car was taken to a Toyota dealer. With his Techstream connected, a tech drove it and says it is the torque converter lockup (or not locking up). The fix: new transmission - $3,100. He said this is a common problem for the V-6 engines (Camry, Forerunner).

While at the dealer, we had the transmission fluid replaced. Maybe there will be an improvement over the next few days.

At least it is still drivable, just a little jerky from 40-50 mph. It smooths out above 55mph.

JetsonES

Ouch, that stinks. But at least it's still driveable for the time being.

DJPsystems

Is the check engine light on? If so did you scan if for the codes?

mdpresco

No codes. No Check Engine Light. Just feels like it has the hiccups!

Years ago I had a similar problem with a Mercury Marquis. Changed the transmission fluid and it smoothed out. No such luck with the ES300.

Is there a fuse that supplies power to a solenoid in the transmission? If I can disable the torque coverter lock up function and the problem goes away I'll be sure that's the problem. I don't want to go through the agony of replacing the transmission and still have the problem.

Has anyone changed a transmission out the top leaving the engine and subframe in place?

mmatheny

My wife's '02 has the same thing at 39-41 mph - 38 or below or 42 or higher nothing! I posted and someone replied to clean the throttle body both sides, and the PCV valve. I also had the pan dropped and filter and fluid replaced and it still occurs. Has 58k on it, too young for tranny issues I would think.

mdpresco

My car started doing this about 30,000 miles ago. Around 150,000. Tomorrow I'm going to have an independent transmission shop take it for a test drive. Today, if asked that model Lexus was known for transmission torque converter lockup problems. He was not aware of any.

mmatheny

Well, just ran across this forum that calls it a lean mixture stumble:


http://forums.edmunds.com/discussion...-with-lexus-es

mdpresco

I read the second link. I have looked at the fuel trims with my scanner tool. It's not running lean or rich when the car is stumbling. The cars in the link are later models and I believe have a different engine.

Like a post in the link, it is most noticeable in the 1700-2000 rpm range.

mmatheny

So what's the consensus - thorough throttle body cleaning, PCV valve cleaning/replacement?? Anything else? I see too many posts about this for it to be extremely rare, so SOMEONE must have fixed it before!