Musada

I have a 1990 LS 400 and so far i've replaced
-Igniters
-Spark Plugs
-Fuel Pump
-Fuel filter
-MAF

We thought the issue was resolved, after I drove it home, about a 30 mile drive. I had no problems. The next I was driving to work and the car just cut off....again....and wouldnt start once again. I had to get it towed back to my dad's place. As soon as we unloaded the car, I went to start it and it started right up!. My father and uncle seems to think that somethings getting hot that causing it to cut off. I called this mechanic and explained to him what was going on. He said the crankshaft sensor is out, and thats whats causing it to cut off, and not start til the car cools down. I thought that if the crankshaft sensor was bad, it would start at all. My problem is the car starts, and then shuts off randomly, and wont restart. Please help, I'm super loss now I've been going back and forth for a few weeks now. All suggestions would be greatly appreciated

I'm also getting a code 13, called Lexus and they said that had to do with a sensor on the transmission...does that sound right, and would that be causing this issue

matchesLS

When you say that it won't start, does it crank over? Have you checked fuel pressure when it won't start? It is possible the car could be vapor locking and not allowing fuel to enter the cylinders. I had a crank sensor go bad on my 2003 Camry due to frayed wiring and it would run fine until it got wet, then it would stumble and sometimes die. As soon as it dried it would run perfectly.

DonCorleone

iTrader: (6)

Two other things to check that would cause this problem;

1) ECU. Mine was sold to me with a bad ECU, diagnosed where it would turn on and run fine but once it got to temp the car would die and not start again until it cooled down enough.

2) Starter relay (green) but this would only explain it not starting sometimes, not dying.

If your mechanic did all the stuff you listed to chase the problem, it's looking like he's just throwing parts at it. Did he test any of those parts before declaring they were faulty?

http://www.lexls.com/tutorials/intro/codereading.html for codes.

Musada

When I say it won't start, I mean it cranks, and kinda starts but immediately dies, until its sat for a while then fires right up.

matchesLS

Are you getting any check engine lights? The ECU could be the problem as well. You can check for vapor lock by relieving fuel pressure from the fuel rail. I'm not exaclty sure if the fuel rails on your car have a shrader valve (like on your ties), but if they do, and be careful doing this, when it dies, relieve the pressure and try starting it again. If it starts it would lead me to believe it was a fuel pressure issue.

Musada

I am getting a error code 13 - RPM signal no. 2. that could be causing the problem?

python

iTrader: (4)

timing belt might have jumped

Musada

how do you remove the ECU? im just gonna get it rebuilt. Any one have a right up or something for the removal, can't seem to find one

DonCorleone

iTrader: (6)

You need to get to it behind the passenger side kickpanel. Take apart the inner lining of the glovebox (bunch of black plastic push in clips, the light and an electrical connector) and the hinges off the retaining bands, that will give you access to two of the panel's upper 10mm bolts. I believe you pull the lower plastic panel off and that exposes the other 2 10mm bolts, The ECU is attached to the underside of the middle (metal) kickpanel with 3 10mm bolts.

fixmiester

If you are failing to get an RPM signal, then the ECU kills the fuel pump, and the engine dies. The fuel pump will only run about three seconds, unless there is a good signal from the RPM sensor. Sounds like it may be intermittent, but that's your problem.

timmy0tool

iTrader: (7)

i'm not sure if this helps any but in the honda world, the fuel pump main relay (and other electronics) is prone to failure due to cold solder cracks. if you look closely at the relay solder contacts there are slight cracks which expand with heat causing a disconnect then leading the car to die and not start until it cools. a simple fix is to resolder the contacts.

this is very common with older honda cars (90s), where the solder used was probably not as good as it is nowadays. this could be translated into the toyota/lexus community. just a thought!

fsuguy

This is so true. My '86 'Lude would suddenly just lose power and begin coasting, scaring the hell outta me. Fortunately, I was able to quickly narrow it down to the main relay in the driver's sidewall(?) Took it out, resoldered what looked like iffy connections and no problems so far!!


In the case of the original poster, though, I think the LS may have an issue with the cam sensor or the ECU. Sometimes the replacement parts, if not within correct tolerances, cause the components in the ECU to fail and leak their innards onto the circuit boards causing all sorts of havoc.

Hope you get it fixed and post what you find out - it will help others!!

Hope this helps.

kLS400

You had the solution from the first post... Crankshaft Position Sensor.

I had exact same symptoms as you... To verify this, as your crank the car the RPM signal should stay at 0-RPM. Also, with your symptoms, you should be able to always start the engine when the engine is cool and not once it is warmed up(can see temperature on instrument cluster to confirm). Should start up always once cold, but never while warmed up until cooled again.

I changed this out(like a 10-minute time, $20 part cost) and it solved a diagnostic error code(sorry, I forget which one). BUT, now the idle is low when first turning on the car and requires gas to keep it running until the engine is warmed up then all is good... So for now, winter time sure sucks, but my next area to look at that I am very strongly believing to be the next problem is the TPS(Throttle Position Sensor). Which many of the symptoms match up with... it might just need an adjustment to raise the idle RPM up and I imagine it might just be that simple! Simple as in 1 part(if you want to replace) and 1 adjustment, yet getting that part off isn't super easy, will take more time, especially with rusted screws

To rebuild the ECU might be major over-kill, yet the ECU from my understanding is common to have capacitors go bad, so might not be a waste to do it, just doesn't sound to me like that will improve your situation.

P.S. I realize this is an old thread, I just posted for anyone else that may come across this, as I believe I have an exact solution to this problem!