KCTalker

I recently brought my SC to another mechanic for his opinion (yes, the car still hesitates), and despite my EGR/no-EGR hesitates/doesn't-hesitate demonstration, he thinks the problem is elsewhere--and perhaps the EGR is simply exacerbating the issue. Anyway, here are some suggestions of his: 1. Get a good, high-pressure fuel-injection cleaning for the car. I plan to do that, because, currently, my SC's hesitation gets worse after a few months, and a bottle of injection cleaner in the tank helps a lot. My guess: it's not helping enough, and a good cleaning may fix the thing forever. I plan to do that fairly soon, and will post here if it helps. 2. He was very wary of the airflow sensor: a little black box attached to the air intake hose, just downstream of the air filter. He tried cleaning it, but that didn't help. His suggestion: If you can find a friend with another SC, ask him/her a favor: swap their sensor for yours and test-drive your car. If that resolves the problem, you know what to do. The up-side: The sensor is held on with something like three screws and an electrical connector; you can remove it in about 30 seconds. The down-side: according to the mechanic, the part goes for about 400-500 bucks! Hence the test. He also suggested some basic fuel-system issues, such as spark plugs, and fuel filter, but said to try those *after* the previous tests. His contention is that the car is running too lean, and that's why it stumbles. Remember, all this is about off-idle hesitation. As for the previous poster whose SC redlines without accelerating--that certainly sounds like a transmission issue to me.

'98 Honda CRX Si. No offense, friends, but the best car I've ever owned. Fast, fun, supremely reliable. It was even great in the snow! Bought it new in May, 1989--and practically had a bidding-war on the thing, mere hours after I posted the ad online to sell it, last summer. Before that... '88 Hyundai (uggh; had to quickly replace the Supra [below] which died) '79 Supra (pretty and cushy, but a mechanically a piece of junk) '76 Torino station wagon (a hand-me-down!) '69 Ford Galaxie 500, with the old 390 c.i.d. V-8. My first car. Big, floaty, cop-car/taxicab/turnpike cruiser. Ahhh....

Hey, Skydiver: Thanks for the info; now I've got a tidbit for you which you (and perhaps others) may find interesting. I've always believed in the old adage that you should never buy a first-model-year car, because it's still got the original bugs that would have been worked out in later years. Indeed, I read numerous complaints about the very first SC400s (was it '92? pardon my memory lapse): everyone carped about the emergency brake lever, and how it dug into the driver's right leg. Bingo: the very next year, Lexus revised the emergency brake lever so it wouldn't hurt anymore. Naturally, then, I figured I was pretty darn safe buying a '95 SC400, since the model had been around for a few years. But recall that this hesitation issue stems from the EGR valve. Well, dig this: I downloaded from Lexus the "New Features" document for the 1995 SC400 (it was originally used, I'm sure, to educate the sales reps), and guess what it says? Allow me to quote: "1UZ-FE Engine On all models, a step motor type EGR valve is used, and the cold start injector has been discontinued." Ha! So it's not a first-year car, but it does have a first-year EGR valve! #$%^&*!!! Good chance its bugs were corrected in '96; this would also explain why so many Lexus service departments are familiar with the--yes, I'll use the phrase--design flaw on the '95. Thoughts, anyone?

Here's the promised pic (if I manage to upload this properly!) of the EGR valve connector. It's that light gray plastic piece above the arrow.

Hey BMAN, Here's an update. Along with the EGR gasket-mod described above, the tech also obviously reset the ECU during the repair ('cause all the radio presets were gone when I got the car back!). I complained to the service rep that the car wasn't much better, but as another poster noted earlier, the car runs flawlessly when ice cold. I made the same argument that you did: namely, this car would have been a failure if everyone who plunked down $50K for it when new had this problem. But the service rep insisted that all '95s have this problem. He also said he'd check with his technician and find out why the car runs perfectly when cold. After this, I kept driving the car, and after about 2-3 days, its performance improved quite a bit! I was shocked! I can only attribute this to the re-set ECU, "learning" not only my driving, but the requirements of the re-configured EGR. Today, the Lexus service rep finally calls me back. He says that his technician reports that (get this) the EGR valve has a built in *heat sensor*, and so doesn't kick in until the car warms up! Ain't that a kick in the !Removed!! It also implies that replacing the EGR valve, as you suggested, wouldn't accomplish anything. My feeling on this--as actuallly suggested by the Lexus technician during my check-ride with him--is that the problem is actually upstream of the EGR valve. Why is it acting so stupidly? Doesn't the ECU control its behavior? Would replacing the ECU fix it? Or is the ECU getting bad signals (as someone else here implied) from bad O2 sensors? I mentioned all this to the service rep, but he disagreed with me heartily. Meantime, my car is running the best it has since I've owned it (only stumbles about 2% of the time), so I'm pretty happy. It's night-time as I'm posting this, but I'll snap a pic of that EGR connector for you and post it tomorrow. I hope my admittedly low-tech feedback helps anyone out there!

Unfortunately I don't have an answer to your question. But I was wondering how you went about eliminating all of your other rattles? I have several of my own that I would like to take care of. Thanks! ← Hey, Obsidianr, I found the magic words to eliminating rattles from numerous Lexus tech bulletins which I found on the web. And those words are "foam" and "felt." That's exactly what Lexus recommends! For any given rattle, first search the web (specifically, sites like this one) for a Lexus tech bulletin ("TSIB") for your exact rattle, 'cause if you can find it, it's your holy grail. And that's because the hard part about eliminating rattles is not fixing them, but rather isolating them. I have a remarkably tolerant wife, and many times, I'll ask her to drive my SC on a nearby bumpy road, while I listen, and press against trim panels and what-not, to find the source of a rattle (without crashing!). A rattle is simply caused by the noise of two hard surfaces colliding when the car hits a bump. So to eliminate it, you need to introduce something soft--such as sponge foam or felt--to absorb the impact at the mating surface. I found an annoying rattle (as if any *aren't* annoying!) coming from inside the seat-back of the driver's seat. After popping off the back cover, I found a hard plastic connector dangling suspiciously close to a metal spring bracket. So I wrapped the connector in an old piece of cloth--and the rattle was gone. I found another rattle *under* the driver's seat: turned out that the seat motor computer (i.e., a metal box) was a little loose, and was hitting the metal seat frame. It was basically pretty tight, so I ripped chunks off an old sponge and wedged them between the box and the frame--and the rattle vanished and never came back. Another nice anti-rattle tool is self-adhesive sponge-foam weatherstripping, which is dirt-cheap at Pep Boys. I used that to eliminate a buzz from the moonroof: turns out that the wind-deflector was buzzing against the roof while retracted (moonroof closed). The giveaway clue here was that there were *already* little pieces of Lexus foam around the thing, so you know it was a built-in rattle fix! But over the years, any sponge shrinks, or felt compresses, and its efficacy is lost. I've also used foam weatherstripping to eliminate a console rattle above the climate control, and additional sponge to eliminate a rear-deck rattle. So now, with the exception of my admittedly-minor windshield ticking noise, the car is all but silent. So I really love fixing rattles, when I can, because it costs nothing, requires minimal technical prowess, and ends up making the car really feel like new. Best of luck with your SC!

Hey Art, I took a check-ride with a Lexus diagnostic technician at a local dealer, and we narrowed it down to either the cowling covers (black plastic shields outside the windshield, under the wiper arms; there's a tech bulletin for a smilar ticking-noise fix on RAV 4's), or the dash itself. To isolate the problem, you need to remove the wiper arms and the two (L &R) cowl covers, then drive the car. If the problem goes away, then it's, clearly, the cowling covers and not the dash. If that's the case, insulate the underside of the cowl covers and put 'em back, and you're done. (That's the RAV 4 fix, too.) After leaving my car with the dealership (where, presumably, they performed the test described above), they said that the problem is the dash itself: the pins that hold it in place need insulating. Sounds simple, but I've downloaded the SC400 shop manual from Lexus--and the dashboard removal requires *eleven pages* of the manual!! It is a *bear* to get to those pins. So I wasn't shocked when the dealer estimated eight hours (about $760) for the fix. However, there's a quick/cheap/easy fix you can try, which I also learned from a Lexus dealer. Get a can of dry silicone lubricant, and spray a ton of it into the crack between the dash and the windshield. Keep a clean rag on hand to wipe up the inevitable overspray. It quiets the noise a bit--not completely--and only costs about three bucks.

Hey 92Lex (and all SCers, for that matter), Just ran my little test, in which I duplicated what the Lexus technician had tried. That is, I disconnected the elecrtical connector from the EGR valve atop the engine, and drove it around awhile with the "Check Engine" light glowing, just to see what would happen. Sure enough, the low-revs hesitation is *gone*! And what the technician told me (namely, that the thing is the culprit) is true. I've also had the chance to drive a little more with his work-around fix (the reduced EGR orifice [created via a washer]), and do notice that the car is improved, by I'd say 50-60 percent. It still stumbles now and then, but is noticeably better overall. So, really, everything this technician told me has panned out. Which of course, raises some questions: Would it damage the car to drive it with the EGR electrical connector disconnected indefinitely? Naturally, this would cause the ECU to log codes from the "Check Engine," but who cares? Could it possibly cause some long-term buildup that might hurt the car's chances of passing a smog-check, after re-attaching the connector? And finally, if the real culprit here is the ECU, which is sending these crappy commands to the EGR in the first place, what's the real solution? I've noticed--from this board, at least--that owners of '93 through '95 SC400s gripe about this problem, but I see no problems with the later-model cars. Was the ECU revised in later years? If so, could a '95 be retrofitted with an (admittedly expensive) later-model ECU? Could the existing ECU somehow be re-mapped? I'm more curious than anything, given the contraints of my ECU-remapping skills, not to mention my budget! P.S.--I could snap a quick digi-pic of the connector in question, in case any other newbies out there (like me) need help recognizing it under the hood. Just post and ask.

Thanks for the info. When you say "test results," do you mean smog-test? I know it passed when I bought the car in June. Or do you mean performing the test you described above? Anyway, the Lexus tech didn't touch any vacuum hoses in my presence, just the electrical connector to the EGR valve. I plan to replicate his little test (yanking the electrical connector) on my own, to see if it indeed makes the hesitation issue go away. (Because he, not I, drove the car after he had pulled the connector.) That's the first issue. Because if pulling the connector truly eradicates the problem, I'll know that the tech's diagnosis was correct, even if his solution wasn't. And if it *doesn't* do anything, then I'll know that the diagnosis (e.g., EGR) was wrong, and I need to resume my trouble-shooting elsewhere.

Hey-- Thanks for the Techron tip; I'll try it. Just did a search on this board for the word "hesitation", and wow, are there a lot of posts! Anyway, here's my latest dealership experience, which I think the readers here will find interesting: After my local Lexus dealer insisted there was nothing wrong with my car ('95 SC4, 83K), I tried another Lexus dealer nearby. As soon as I described the problem to the service manager, he said, "A '95? Oh yeah: EGR gasket modification!" Huh? I hadn't seen this on *any* posts here; it certainly seemed intriguing. Still, I insisted on demonstrating the issue to a technician in a road test, so their top diagnostic guy hopped in the car with me. Soon as he gave it gas off the line, it stumbled. Then he said, "Let me see something," and pulled over to the side of the road. He then popped the hood, and yanked out an electrical connector from the engine. "What's that?" I asked, and he replied, "EGR." We got back in the car, which was glowing a "Check Engine" light--and the problem was gone! According to the tech, it's a problem with this car, stemming basically from the way the ECU is programmed. He said the EGR system is supposed to open up at highway speeds to burn off un-burned exhaust gases, but sometimes, the valve opens up when you first accelerate, and this, he said, is the cause of the problem. And he said he knew of a fix, or more realisitcally, a work-around: He offered to modify the car, by installing a washer in the EGR valve gasket to effectively reduce the size of the orifice. He said that he could only reduce it so much, because if he did it too much, it would trigger a "check engine" light which, here in California, means your car fails its smog-check and is thus illegal to drive. (Not to mention the fact that a continuously-glowing "Check Engine" would mask any *real* problems that arise.) So. I okayed the 95 bucks for an hour of shop time for him to make this alteration. And I just got the car back. I was told that the car would be better, but not perfect. I'm not too sure I agree. It still hesitates, perhaps a little less than before, but I think I've had better luck with fuel injector cleaner! (And now look forward to trying a big bottle of Techron.) The technician also confirmed what everyone here's been saying about the ECU, although he added that it's best to disconnect the battery for about *ten* minutes to truly blank it out. He said it would then "forget" its last 1,000 miles of driving patterns, and re-learn them from scratch. He also advised driving it hard, in "power" tranny mode, during this learning phase. Okay. So, if any of you are still with me after this War-And-Peace-length post, I'd be curious to others' reactions. Anyone else wanna try disconnecting the EGR valve and seeing what happens? Please note that mine is a California car, not 49-states, so I don't know if that'll be a factor. Anyway, just thought I'd share my experience, since this is *clearly* a designed-in problem that's endemic to these cars.

Hey, Skydiver, Problem is still there. Have since replaced timing belt, water pump, drive belt, power-flushed the tranny, replaced the idle-speed control valve (which turned out to be the true source of the stalling), and while all that stuff is certainly good for the car overall, I still have the hesitation issue. A bottle of fuel injector cleaner seems to help--but the help only lasts for about 3/4 of a tank!! Insane. I brought it back to my local Lexus dealer a zillion times, but they tell me the car is fine. I disagree: I drove two other SC400's right before buying mine, and didn't experience the issue on the others. Coincidentally (considering you're replying to a post I logged this summer), I'm about to try my luck with another Lexus dealership, a little further away, and may have some info/updates sometime next week. Meantime, if you happen upon any other info, please post it!

Hey all: I've got a '95 SC400 (82k, nice shape) for about four months now, and have been able to eradicate just about all of the interior rattles it had--until now. The temperature's just dropped (here in So. Calif), and now there's this annoying rattle that seems to come from the top of the dashboard, all along the bottom edge of the windshield (where it meets the top of the dash, in the neighborhood of the defroster vents). I did a little searching, and it seems there's a Lexus Technical Service Information Bulletin (TSIB) about this for the RX--which would probably be helpful--but I couldn't locate the bulletin itself. Regardless, I'd *love* to fix this, and I'm guessing it's not uncommon, either. Any tips? Help? A location of that TSIB? I can't even find out (via web-searching) how to remove the complete dashboard anyway (the whole, vinyl top portion that rides atop all the instruments, glove box, etc.). Any help would be greatly appreciated. I've got this nagging feeling that if I can get to the rub-points, some basic spongy weatherstripping will silence the problem, as it has for 99% of all the other interior noises I've found on this thing. Thanks in advance, fellow Lexites!

Hey: I had the same issue with my newly-purchased '95 SC4. You can do what I did: Pull one of the existing buttons out and bring it with you to a well-stocked auto parts store. Compare it to the pre-packaged "panel fasteners" you'll find there. I didn't find a 100 percent match, but I did find a 90 percent match for about two bucks, and it worked perfectly. Once they're installed, you can't tell anyway: all you see is a black plastic cap. Good luck!

Hi, and thanks for the replies! First, what's the "ecu"?? For that matter, how do you reset it?? It sounds simple; Theodore says it helps; and I'd certainly love to try it. As per jzz30's questions, the tranny seems to shift fine; its fluid is clean with no burnt odor, etc. Spark plugs are new. Spark plug wires were just checked by a mechanic and deemed "fine" (but not replaced). Also, as per the timing belt, the owner's manual doesn't say when to replace it--unless you're driving your SC like a taxi! In my experience with other cars, 80K is about time to do it, so at 78K, it's pretty near due. Any other thoughts? Thanks again for the prompt replies!

Hello, all, from a brand-newbie! I just bought a '95 SC 400 (87K, nice and clean), and since I'm brand-new to the car, I've got a question I think you veterans could easily answer. Bear in mind, I'd been driving a five-speed, four-cylinder car for 15 years up to this point, so I honestly can't tell if it's the car, or if it's me. Here goes: At low speeds (5 mph) and low revs (1,500 rpm), when I give the car very light pressure on the accelerator, it seems to hesitate. However: the thing idles like a champ, races to redline easily and smoothly, and gives flawless performance under every *other* set of circumstances. Am I, perhaps, simply not giving the car enough gas for the automatic transmission to really "bite" into the gearing sequence it wants? My wife's got a '95 Celica automatic, and I don't notice this phenomenon when I drive it. Two more bits of background about the car: 1) When I first brought it home, it stalled twice, despite otherwise-perfect performance. I brought it back to the dealer, who found, and replaced, a clogged gas filter. No stalling since. 2) Today, I dumped a bottle of fuel injector cleaner into the tank (I'm suspecting the previous owner may have skimped on gasoline, or simply never drove the car very hard). The cleaner, combined with a nice, high-revving cruise for about an hour, seems to have helped the car, overall, enough to notice. I still can detect the hesitation I described above, but it's pretty faint--just present enough to notice. I put a quick 100 miles on the thing with the injector-cleaner so far; think the performance will continue to improve? Has anyone else noticed this "hesitation" I've described? Or am I just way too nit-picky? Anyway, thanks, all, for taking the time to read this (way-too-long) message; I'd appreciate your thoughts!