1992 Will Not Idle

[XL2007]

Problem surfaced on the way home. I stopped at a red light only to see the RPMs fall to ZERO. Had to pop it in N and restart it, but now it won't idle on it's own -- I have to keep my foot on the accelerator to keep the RPMs up.

At this point, I have no clue as to what could make a car that was idling just fine to suddenly stall if you don't keep giving it gas.

[AzHotLS]

Did you do an "idle" search and read through some of the threads?

Here is one thread I found doing so, not sure if it helps but may give you an idea:

http://us.lexusownersclub.com/forums/index...377&hl=idle

[XL2007]

Did you do an "idle" search and read through some of the threads?

Here is one thread I found doing so, not sure if it helps but may give you an idea:

http://us.lexusownersclub.com/forums/index...377&hl=idle

I browsed a few threads with somewhat similar problems, but none of them really fit the bill. My car basically stalls out coming to a light.

I doubt it's related to the trunk wiring -- and if it helps, I topped the car off with a full tank last night. I hope it's not bad fuel causing the problem.

[mejojo]

Fuel Filter? How many miles? Any record of filter having been changed?

When it runs, will it accelerate?

Joe

[MidNightGS430]

Its hard to pinpoint without more details. It can be a number of things from: Fouled plugs to Bad fuel filter, Bad fuel, Injectors, Fuel Pump etc. ????????? A good way to check if its getting fuel is to relieve the fuel pressure out of the fuel rail, And then start it and turn it off and relieve the pressure again. And if its not getting fuel it wont relieve any fuel at all!! If its getting fuel it will squirt out of the rail. Make sure to wear safety goggles if your going to do this. And thats one way to tell if the pump is doing its job, The pump will make a loud whining noise when its ready to go as well.....

[XL2007]

Fuel Filter? How many miles? Any record of filter having been changed?

When it runs, will it accelerate?

Joe

This car has a LOT of miles on it. 350k.....at least until the odometer broke. :o

To my knowledge, there is no record of the fuel filter being changed. I'll double-check just to make sure and if not, I may just go ahead and have it changed out.

Acceleration is no problem. The only trouble is keeping it at idle -- when my foot is taken off the gas, the car simply quits. I have to keep my foot on the pedal to keep it running.

I've checked the fuel injection and MAF sensor. I don't see any problems, but I'll double-check when the weather isn't so inhospitable. The spark plugs and wires were changed several months ago (OEM spec if I recall...) and the oil and oil filter were changed just 3-4 months ago.

One more thing: the transmission goes in and out of R and D with a SLAM above 1000 RPM. It's probably not related to the problem at hand and can probably be taken care of with new fluid or a flush.

[XL2007]

Its hard to pinpoint without more details. It can be a number of things from: Fouled plugs to Bad fuel filter, Bad fuel, Injectors, Fuel Pump etc. ????????? A good way to check if its getting fuel is to relieve the fuel pressure out of the fuel rail, And then start it and turn it off and relieve the pressure again. And if its not getting fuel it wont relieve any fuel at all!! If its getting fuel it will squirt out of the rail. Make sure to wear safety goggles if your going to do this. And thats one way to tell if the pump is doing its job, The pump will make a loud whining noise when its ready to go as well.....

I removed the EFI fuse and relay in an effort to isolate the problem. Without both, it's not getting any fuel at all. Reinstalled, it gets fuel.....as long as you have your foot on the gas pedal. Otherwise, it won't receive fuel on it's own.

[93ls400walt]

Other than no fuel. The idle is controlled by the IACV. If you can keep the rpm up with the gas peddle I'd look at the iacv.

[don corleone]

This car has a LOT of miles on it. 350k.....at least until the odometer broke. :o

mine too. odo stopped in 2001 w 189k. this is according to carfax. car hit 90k in 98 and when i changed the tb/wp last year the wp had the numbers "98" on them. 90k service. my new one has "06" . and the car is still rollin. whenever anyone asks me how many miles are on her i just tell them 300k. a member on here had a 90 ls and the odo stopped at 200k. he replaced it and hit 200k+ on the new one.

but about your problem when i took off my throttle body any broke the gasket my car did that on the way to the dealer to get a new gasket. so it sounds like a vacuum leak. just buy some vacuum hose from autozone or toyota (lexus costs more) and then move on to the hoses on the pwr steer pump.

[XL2007]

but about your problem when i took off my throttle body any broke the gasket my car did that on the way to the dealer to get a new gasket. so it sounds like a vacuum leak. just buy some vacuum hose from autozone or toyota (lexus costs more) and then move on to the hoses on the pwr steer pump.

Thanks. I'll start looking at the IACV and track down any split/worn vacuum hoses asap.

And now it seems I've lost the owner's manual, which I need to look up the interior fuse box schemata. Anyone have an online version that could help?

[kenmac]

Try cleaning the Throttle body out as I had the same problem with my LS and this was the culprit.

Cleaning Throttle Body

[nll714]

I had the identical problem as you. 95 LS400 with 144k miles on it and runs great. Buzzing down the road like normal, came to a stop light, RPMs dropped to zero and the car shut down.

Long story short, had the idle air control valve replaced and now good as new. I hope this is helpful.

[XL2007]

I had the identical problem as you. 95 LS400 with 144k miles on it and runs great. Buzzing down the road like normal, came to a stop light, RPMs dropped to zero and the car shut down.

Long story short, had the idle air control valve replaced and now good as new. I hope this is helpful.

The weather around my neck of the woods' been crazy these past few days -- raining and bitterly cold -- something you really wouldn't expect a lot of in the deep south. Hopefully the weather will let up enough this coming week so I can get some work done!

Thanks for all of the advice B)

[SRK]

Well it's not the injectors, the spark plugs, or the wires. It's air flow. Either the IAC valve as some have mentioned, or one of the hoses from the mass meter has come loose and the engine is getting "false" air. Probably very simple.

[XL2007]

I had the identical problem as you. 95 LS400 with 144k miles on it and runs great. Buzzing down the road like normal, came to a stop light, RPMs dropped to zero and the car shut down.

Long story short, had the idle air control valve replaced and now good as new. I hope this is helpful.

Seems simple, but when I looked online for one from the usual auto parts stores.....

http://shop.advanceautoparts.com/ProductDe...506&PTSet=A

$985??????

This much for what seems like a simple part?

[AzHotLS]

It's $538 at Carson Toyota : LINK

Try cleaning it first. Step by step instructions.

[XL2007]

I managed to clean the throttle body today. And man, was it just gunked up! But it still didn't fix the problem. Also, the TPS seems to be in good order, as I can adjust the idle revs....when I'm holding the throttle cable so that the car doesn't stall out.

I saw the step-by-step guide for the ES/RX concerning the idle air control valve, but I can't translate that to the LS400. If I can just find where that is, that'd be appreciated. I read in another thread that it was under the power steering pump, but that just doesn't sound right -- it has to be around the throttle body/intake or at least the air filter area, right?

[AzHotLS]

Sorry, I didn't notice the instructions weren't for a LS400...

This thread has a link to a document that will show you where it is and how to get it off:

http://us.lexusownersclub.com/forums/index...showtopic=42315

The Air Control Valve located under the power steering pump controls power steering assist. When it goes bad, it causes PS fluid to be drawn into the intake manifold. You can tell when it goes bad if you see blue smoke out the exhaust right after starting the car. It's shouldn't affect idle RPMs. It's shown in this thread:

http://us.lexusownersclub.com/forums/index...ost&p=38812

Not in the highlighted box but to the right.

[XL2007]

I forgot to add that I found what apparently looks like TWO TPS sensors on the throttle body. Maybe because it's a TRAC model, but it looked plenty different than the pictorial guides I have. Now TRAC (which hasn't been working previously) stays on consistently. I've been out of town this week and hadn't been able to work on the car as much as I wanted to.

I'm going to double-check the TPS, just on a hunch, perhaps even get a new one and see how that works.

I don't see any blue smoke or anything else that might indicate a PS fluid leak or the IACV sucking in said fluid.

[XL2007]

HERE'S A BIT OF AN UPDATE:

So I got back to messing around with the car, making sure that I've looked over everything else before tackling the IACV. So I rechecked and readjusted the TPS and check the throttle cables and other little bits. At this point, the car hasn't moved beyond 15 feet since the problem arose, so I decided to take it around the block once traffic cleared up enough. Two-footed driving came in handy :/

I get back in the driveway and put it back in park.........and it now IDLES. Problem is, it's idling at about 350 rpm and getting lower as time lapses. So I go back and readjust the TPS, only for the car to give out, again. I get back in and start it up.....

.....and the battery's stone dead.

I get it jumped off (which apparently didn't take much) and restart the car. It fires up beautifully and holds an idle at about 650-700 rpm. The next day, the car was a bit sluggish firing up. Apparently the alternator's charging it just fine, as I haven't had that problem again, just when it sits up overnight. At some point, I'll take the battery to an auto place to have checked out...or if I need a replacement.

Pretty weird how the initial problem ended up "going away" like that. I might have to look into that trunk wire ground situation as highlighted in a few other threads, just in case.

[David Culberson]

Sounds similar to my wife's 1992. It died at a few lights shortly after I resurrected it from the dead (bought it with a broken timing belt) then it decided that it wanted to run just fine after all. Much later we had all sorts of weird stuff happen and it turned out to be the trunk lid wiring. (Two wires were broken.) I don't know if it was related but it's entirely possible. It's easy to check, so check it, and let us know!

Before patching the broken wires, the car would only go into 1st gear with the headlights on, but all gears with them off. It would down shift whenever I hit the brakes. The reverse light would light up whenever I hit the brakes. All that behavior is gone after patching the wires.

The symptoms vary wildly, though, based on which wires are broken. So don't assume since your symptoms aren't identical that it's not the same problem. But if you don't see any broken wires, then you're probably facing something else wrong.

[XL2007]

Turns out a bad battery was the culprit. So I had it replaced under warranty and everything's pretty much back to normal.

[amcdonal86]

Turns out a bad battery was the culprit. So I had it replaced under warranty and everything's pretty much back to normal.

Glad you found the solution to your problem. This was an interesting read! :)

[XL2007]

Turns out a bad battery was the culprit. So I had it replaced under warranty and everything's pretty much back to normal.

Glad you found the solution to your problem. This was an interesting read! :)

It's not over.

I ran to the grocery store last night. On the way back, all of the symptoms came back -- the refusal to idle, and the super low (350-400rpm) idle on the off-chance that it does.

I'll get a new TPS AND check the trunk lid wiring. If that doesn't help, I'm just gonna send the darned thing to the shop so it gets sorted out (even though that'll cost $$$$$ ).

[don corleone]

does the car stall out or does the idle drop to 200 rpms. idle is affected by the "air control valve" shown in the picture. it has two hoses attached to it one that connects to the air intake and another that is connected to the intake manifold. air flows thru these hoses and will affect your idle. if the idle is normal when the car is cold and drops when it warms up then this valve needs replaced. about 100 at a toyota dealer. if the car stalls out then you either have a vacuum leak or your tps adjustment is slightly off. lexls.com has the official method for adjusting the tps

http://www.lexls.com/tutorials/EFI/tps.html

the attached pdf shows the vacuum lines.

M_vacuum_diagrams.pdf