LS 0181158

Good advice all!

91L3xus, I may have seen your car this morning (Dec. 8). Is it black in color, missing several center wheel caps? Didn't look THAT bad :-). It was the only ES 250 I saw, and I was there from about 9 to 11:45 AM. I think that car had a gray interior, not a tan one, so maybe it wasn't yours. What were you getting done to your transmission again?

914lps, I have disconnected the battery any time I did anything under the hood related to this problem (including MAF replacement). However, I did NOT clean the MAF before I put it in. Here's why; I tried to clean my original MAF. However, when I took out the three screws, disconnected the plug and pulled it out, I could not see any "little wires" like I have read I will see. There's just a 2-3" plastic piece that sticks down inside the metal box. I sprayed fast-drying contact cleaner on that piece anyway, but when I reinstalled, the car would not even run with my foot ON THE GAS. I was later able to drive it a little bit (around the block), but overall driveablility was not restored until I received the new junkyard MAF in the mail and installed it.

And SRK, tachometer always seems to correspond with the actual RPMs--including unruly idle fluctuation.

Upon my inquiry, the dealer said they would not charge me for any further diagnosis, stating that my initial $111 would cover any other investigation until they actually began work on the car. As I noted above, they had my car for nearly three hours, and finally returned to tell me that although I drove the car there with the check engine light on, the computer was not throwing any codes at all. Because of this as well as the randomness of the problem with no apparent trigger, the tech believes that the ECU computer itself is basically shot. He was willing to test by swapping in an ECU from a "certified" car, but said it would take another six hours or so before the part was available to him. I couldn't wait any longer, and he assured me that he was pretty sure the ECU was the problem. He said he did "check the inputs and outputs" of my ECU, but really didn't have any other clues. He also stated the car is indeed running "very rich" when the light is on (which must be why gas disappears so rapidly while this is going on and my back bumper is BLACK around the tailpipes).

Since 11:45 this morning, I have driven my car off and on all day until now (10:00 PM), with absolutely no problems. I am keeping my fingers and all my toes crossed, but experience up to this point suggests the issue will probably return.

I'm wondering how much sense this guy's conclusion makes--or do I really just need a fuel filter or, at most, a tuneup. Remember, there are now apparently no trouble codes when the check engine light is on.

Going to the Lexus dealership tomorrow. Tonight I drove the car, and the check light DID finally come on and the car ran with reduced power. However (I guess because of the new air filter having something to do with it) it does not cut off anymore, nor does the engine run rough anymore--it simply cannot be revved up very high and has greatly reduced power. Still, I can get up to 75 mph pretty easily.

ALSO, I noticed that when the light is on, the car blows distinctly black smoke and burns through gas at an alarming rate. It does not do this under normal conditions (without the light). I believe this means the car is running rich (too much gas)??

I will see what the dealer says tomorrow. Thanx again for your inputs.

OK, I will do that. Others I know have recommended I do the same thing, so I feel even more vindicated now. Hopefully this dealership will deliver the "customer service" Lexus is known for when I request a free diagnostic and point out their poor attention to detail the first time.

OK, so--fuel filter (I was already thinking about that), tune up, and then possible fuel pump. Would a clogged fuel filter actually cause the car not to idle--to actually cut off, or idle erratically? When I try to rev the engine up to keep it running, it'll rev smoothly, but the tach needle will rapidly and relentlessly "dive" toward 0000 rpm before zooming smoothly back up in keeping with where my right foot is (this of course is only when the check engine light is flickering on and off).

Also, the engine has recently been more smooth if the light is on, but acceleration is painfully slow because there is very little power and the transmission starts out in 3rd gear (I usually shift it manually 1st, 2nd, etc when this happens). Pressing the gas more than 1/3 way down will cause the fluctuation and bogging down, but the engine is smooth while only feathering the throttle. Driven in this way I have been able to cruise at 75 mph. However, the engine feels like it's running either to rich or too lean.

I'm super confused how the car can drive with NO PROBLEMS for one or two days (sometimes over distances of 200-300 miles), being parked, restarted, driven, etc.--no issues. And then all of a sudden, the problem returns. It does not seem to be dependent upon temperature, moisture or any other atmospheric factors. Can a clogged fuel filter be great for several days and then cause these massive problems?

The check engine light will go away on its own when the car decides to "act right". Last night, it came and went within a minute, all at 70 mph.

Do you all think I should take it back to the dealership and demand another diagnostic, this time for free? I can't pay $111 for them just to stick a plug into my engine compartment and read the code. Also, I was chagrined that the first time they did not notice any of the loose clamps on the hoses and try to trace the problem to a simple source, instead quoting me a $1,300 repair.

Anyways, thanks for those speedy responses--this a really a great forum!

I recently purchased a 1993 LS 400 with 204K miles. The car usually drives fine--when it does it is actually the quietest, smoothest, most solid car I've ever driven. One would think the car doesn't even have 100K given how well it normally drives. There are no warning lights when it drives this way.

However, since the beginning, there has been an issue with the check engine light illuminating and the revs fluctuating violently as the light flickers on and off. The car naturally loses power as well. When this is happening, taking your foot off the gas (especially at low speeds) will result in stalling. The car will restart, but it sometimes must crank for a few seconds, and the engine will stall immediately unless you keep your foot on the gas to "catch" the revs when the engine fires. Mind, this problem only happened occasionally, and letting the car sit would usually make it go away.

I took the car to a Lindsay Lexus in Alexandria, VA, and they charged me $111 to tell me that the problem related to the mass air flow sensor--a $1,100 part according to them. I ordered the part (with a 90-day warranty) from a junkyard for $165 and installed it. I disconnected the battery and pulled the EFI fuse as well. Following this, the car idled smoothly for 15 minutes with no check engine light, and then it cut off.

I've since found that several hose clamps on the air passageway to the engine were loose. That once again cured the problem only temporarily. Last night I replaced the air filter, which was pretty dirty. So far the car has run fine, except for a less-than-1-minute period on the highway at 70 mph when the issue reoccured, then went away.

I'm all out of moves here--can anyone think of other things to check? I feel like it's got to be another sensor somewhere, the way the problem comes and goes randomly, with no apparent "trigger".

Thanks in advance for your thoughts.