Cmann

Im new to this and this is my first post but I'm going to get right to it. I need some help. I know this isn't a mechanic shop but my lex is getting ridiculous. I have a 93 ls400, it's not any modifications I know of, and I've owned it for about 2 years. I never really had any problems out of it besides suspension, and I always do an oil change and spark plugs, oil filter you know regular tune up, maybe every couple months( may be too much?) but it's an old car and I try to keep it up. I have changed things like the alternator but nothing major.

So the problem is within the last three months. First, the car (about three months ago) starts idling crazy up and down. And sometimes would stay up, and sometimes so far down it cuts off. I also noticed it shifted hard. So I gave it a tune up, have to admit never changed wires,and also changed tranny filter and gave it new fluid. Tranny changed for the better, but idle was still bad. So I found out how to use obd1 and diagnose codes. Got a 31 maf or air flow meter signal. I got a used one from the junk yard and it was better....for a week then it came back, with a vengeance. I gave up and took to a mechanic they diagnosed it as having a bad ecu. So I sent the ecu off to be rebuilt; and got it back. When I hooked it up, It did a little jumping up and down then smoothed out; I was back in action........for two weeks this time. When it started, the problem again was the idle was just at 2000 in park and 1000 in drive. The car drives itself!! Sometimes it would idle down after it has reached the temp on the gauge,which never runs hot, and it would idle great but the idle stopped coming down. So from the time you start the car, until you turn it off, it just idles at 2000 rpm. It doesn't matter if you drive it for hours, it doesn't idle down it just stays at 2000 until you turn it off. I'm a confusing person so I'll clarify if you don't get it. Each time i have something replaced, the high idle comes back weeks later. Now I've replaced an maf sensor and computer, i think hey maybe the throttle body is clogged. I took it off cleaned it with carburetor cleaner real good, let it dry, reattached it, and made sur everything was back, officially connected like it supposed to be, and cranked it up. It ran funny for a few seconds, smoothed out, and a week later, here we go again.

So I got another mechanic, who said it was the tps. Again I went to the junkyard, grabbed em, and threw them on. I can tell the difference in my original tps and the new ones, because my originals didn't change the idle when you adjust them with the car on. So i now can adjust the idle from 2000 to 1500 but it is still way too high. My opinion was the iacv, which I also grabbed from the junkyard. I cleaned mines and didn't get a difference I also cleaned this one I got from the scrap and saw no difference. Out of desperation, I've replaced the fuel filter, put in gas treatment let the gas run out, and filled back up. No difference. I've replaced the PCV valve, just cuz. . Next is ECT sensor. I've checked all my vacuum hoses, even though I think that would make idle low if malfunctioned. If I pull my large vacuum hose off of the intake and leave the other hooked to the iacv while car is on, I can smooth out the idle by adjusting my finger over the sucking hose until I hear it smooth out. When it warms up is when it starts slowly climbing in rpm's to 2000; but I can also tell when it's about to do it because i smell something. I want to say it's gas but im not sure. When I'm driving you can smell it, but not real strong. If I cut the a/c, which works, on the idle will calm down a tad bit. But I thought it would climb a tad bit. And when I'm driving if you hit the gas, it kind of acts as if it's not getting gas, just for a split second, like it's cutting off. Also while I'm pulling up to a red light, and I'm stopping, you can feel the tranny downshifting itself until you stop because it's like the car is just tryna go.

Now I'm home, and I turn it off. If I try to start it back up, you smell gas and it won't start. You might have to crank it 15 times, really, until it starts. Then if it starts, the rpm's shoot straight up to 2000, and a puff of dark smoke comes out the tail pipes like the car was flooded; but it's on. And it's guzzling gas, which it never did. I know this is long, but bare with me.

So today I took a rest, mostly. I unhooked the EFI fuse, then turned the key to on, then off, and unhooked the battery for about 30 min so I could reset everything. Still no luck. Now school is coming up in about 2 weeks, and it's crunch time. My school is way too far for this *****. You know.

What is my next step? I've learned a lot about this car, and spent a lot of money. I refuse to throw it away. Besides this, I'm having other major problems like dash lights out, and only temp and rpm needle works, and my disk changer stopped working; so I had it replaced by a local, very reputable, but expensive shop to have cd player put in; but that was two years ago. I have noticed, while looking for any leaks today, that I found what I think is an oil leak off of something behind the throttle body; between the engine and the wall of the car almost in the middle. I can see it from the bottom better than the top, but I can't see were it's coming from. But never the less, the main problem I'm worried about is this idle situation.

Please help a Lexus owner out. What should I do?.

shoob

you have described my exact situation..... 93 ls400. are you getting the check engine light and trac off light? im leaking what looks to be either power steering fluid or transfluid from higher up in the same location.

but my idle varies....1 minute it will race to 2000, the next minute it will barely idle, and wont have enough power while driving it, to get to 55 mph.

im also getting codes:

cel- 24, 31, 71
abs- 18
trac- 43

shoob

does my post describe your issue as well?

https://www.clublexus.com/forums/ls4...oing-nuts.html

Cmann

Sort of my car really isn't really turning off or calming down and if you shut it down it won't turn back on due to flooding don't get it. Starting to not like this car, wanna go back to Benz right now

steve2006

Have you checked the CTS ( Coolant temperature sensor) there are 2 one for the gauge and the other to the ECU.
If this is faulty it could be telling the ECU the engine is running cold all the time even when fully warmed up, this would explain the constant high idle speed.

https://www.clublexus.com/forums/ls4...ange-pics.html

mikes7ke

iTrader: (1)

I'm too busy right now to read the full post. For what it's worth I fixed an erratic idle on mine by fixing a vacuum leak.

Cmann

Ok it was the ecu's ect right in front of the engine! The damn thing was only 15 dollars were im at ,from autozone.The car runs 80% better! But it keeps surging down and it even cut off at a light but it started right back up and no more high idle but could my spark plugs be the problem or something else? The car has been running very bad for about 2 months maybe longer.

Cmann

And I would also like a reward for the longest first post ever on clublexus forums

RA010623

iTrader: (1)

wow please space your paragraphs it's so difficult to read :P

trukn1

Longest first post ever; nah. Non- punctuated maybe, and definately the longest run-on paragraph( fixed that for you) but not the longest post. LOL!!

Anyways,, the problem you describe, as your main problem, sounds like your coilpacks are slowly dying on you. These WILL do strange things to the idle, you WILL smell gas, and you WILL get the black smoke. This is not the "fix it all" solution to your problem, as it seems you have several. Some of them, you seemed to have already addressed. Have the coils checked/replaced and this SHOULD solve a greater deal of your problems. Then it is on to the next one, which are minor in comparison to the idle.

SkulCracka

cam sensor wires touch belt? bad fuel cap oring? truck wire harness?

cobalt91

If you were driving it with it running rich, it may have fouled several of the plugs. Also on the driver side cover for spark plug wires, there is a slot for the coil wire t go to the distributer. Make sure that the wire has not been pinched or damaged by this cover.