evileagle

So I have a 92 400 with about 120k miles. Problem is sometimes (generally when it's hot out) when the car gets to full operating temp it will drive fine for a short while, then the car wants to stall. When you press on the brakes it will actually stall and NOT start up again for quite some time (about 10 minutes or so, probably till something cools down a tad). I've taken out the iacv and it looks clean on the inside. Also did a full tune up (plugs wires caps rotor etc).

Any input will be greatly appreciated!

Dream36

You can try the coolant sensor at the front of the intake manifold. That would be my first guess. However if it Stalin with the brake applied it could be a vacuum leak as the brake booster uses vac ref to apply pressure. Check the bottom of your PS pump to see if those two vac lines crack broke or came off. After that check your intake pipe for leaks and follow all ur vac lines.

It could also be spark related. You may have a bad ignition coil and are running a 4cyl and that lil extra load from the booster could be the tipping point. Doubtful but worth a shot.

Other than that maybe ECU?
I know I removed all my little gremlins when installed a refurb ecu

Hope I helped

1JZPWRD

iTrader: (59)

This is a great place to start.

V8drummer

iTrader: (5)

You could also bypass the fuel pump ecu.

evileagle

So I forgot to mention...when the car stalls, you try to turn the car back on and it runs for less than a second and stalls again. If you wait like 20 minutes it will start again and hold until whatever it is that's faulty seems to heat up again.

evileagle

-Ignition coils checked out ok, going to test for leaks next. I ordered a coolant sensor so well see if that does the trick.

Thanks guys for your help, if anyone has any other ideas please give me your input!

V8drummer

iTrader: (5)

still sounds like fuel pump ecu.

evileagle

Replaced coolant temp sensor and all small vac hoses...found a couple hoses that were cracked/leaking, but issue remains. Took over an hour to start again. Any ideas?

evileagle

I will bypass the fuel pump ecu and see what happens...

Keep in mind this is a bone stock car. I'm going to start looking for an ecu replacement and maybe that will help.

Dream36

You need to try and replicate your results while sitting still (instead of at a red light). Take a long drive, when you get back try and stall the car, it should cause a code and that will help u find a problem faster. I stand by my original statement that it did sound like a vac leak, problem is with new lines it should have stopped. New or rebuilt ECU will give you a good baseline. Where are you located? Maybe a local member can loan u an ECU (if near delaware PM me I have a sparr)? Other than that if say a coil. I blow coils every couple months as I can't afford the better ones (I got pepboys coil on too and autozone on bottom both are junk compared to Toyota or federated.

Hope it helps man, I know how frustrating it gets , I started with plugs, wires, rotors, caps, coils, sensors, then ECU. In my case the ECU fixed most of the issues but I haven't had a new coil on since the ECU swap, I'm sure once I get coils they will last longer this time.

DVSBSTD

I am new to the forum and Lexus cars or any used car for that matter LOL. And since I am also in DE, I thought I'd ask advice here. Sorry if this runs long, but I'm just a mom who is beside herself. I just bought a 92 SC400 for my son's high school graduation (and since we are so not wealthy, he didn't get a brand new lexus with a big red bow like the commercial haha). Anyways, when we first bought it, the dealer couldn't get it started and then later we got a call saying he got it started (it didn't start cause theft system wasn't reset or something). It ran rough, I could tell I'd have to put 2 new back tires to pass DMV (haven't gotten to yet) but it has 190,000 miles so I didn't expect much. We got a tune up at jiffy lube, replacing serpertine belt. It ran okay for a couple days. Well a day later it stalled on my son and they couldn't get it jumped or restarted. Sent it to a repair shop (they had it like a week) codes called for O2 sensor replacements and they replaced idle control motor. Well they tried to figure out the issues more but really couldn't. The guy said something like the info was going from O2 sensor to computer ok but computer wasn't relaying consistently the info back to the car. We were able to drive it home, at a stop at drug store, my husband had to try to start it a couple times but it did and he got home. (Just an aside, that night my son and husband replaced the AC component in the dash) Then next day, it would start but immediately stall and not stay started. Then yesterday, my husband and I (who really are not mechanically handy) pulled up the driver side carpet and removed the fuse box and pulled the fuse to "reset" 'cause he saw on internet that it should be reset after O2 sensors and we were thinking shop didn't do this. Well it still wouldn't stay started, so I said try this other "Ecu" something and with that one out (it did stay started) and he thought that fuse was for theft system. and since I had read somewhere that sometimes car won't stay started if theft system thinks it's a bad key (and we only got valet key); so I said let's leave that fuse out. So it stayed started we took it for a couple mile ride. Then when my son got home, he took me for drive to drug store; and to go home sure enough after we started her; she wouldn't stay started; so I had to drive car home, constantly feeding a little gas to car at all times (even while I was stopped) and also coolant light on. I have read so many forums and although I am not mechanical..I'm thinking we are going to have to try that fuel pump ecu mod and sodder the wires thing (taking rear seats out)...but I'm scared I'll screw it up more. I bought the car for 2000 (from our home equity) which I guess was prob too much and then spent that much to repair shop and now really don't have many funds left.....and I still have to get this through DMV inspection and register it in my name and PA temp tag expires on the 25th. Luckily my son's grandfather is buying him the tires as a grad gift, but I don't think he'll get him tires on a car that doesn't run. Please tell me what your advice is..I am getting hopeless. Thank you!

oldManTan

that really sounds like an ECU problem. it's in the driver side foot well. peel the carpet back like you did on the driver side and there should be a big silver thing, that's the ECU, unplug it and open it up, and look for leaks in capacitors. white stuff on the circuit board. ECU looks like this

DVSBSTD

Thanks so much for the pic. I think that's what my husband said we are going to try on his day off. I know he mentioned he found somewhere to the send ours and then we get a new one; but I have also seen places where they rebuild it? Have you had any experience with good online suppliers? If so could you share their name or link? Thanks so much again for the replay, Paige