Hello to everyone,

I am having some weird problems with my 1997 Lexus SC400, and NEED some help!!!

First off, I've done my homework before asking, went thru countelss threads, diagnosis E1+ ET1, learned how to ECU pump bypass(not done yet, just learned how to), etc, etc, before using my last resource; HELP FROM MEMBERS!!!!

Ok here is are the symptoms/facts:

1) Car was stored for little over a year without a battery. Before that car ran perfectly.
2) New battery was installed a week ago and started the engine just fine.
3) Drove the car for 45-60 minutes just fine, then it suddenly died on a stop light.
4) Engine refused to start after numerous attempts.
5)After a couple of minutes without attempting to crank it started just fine, lasted 5-6 seconds and died again.
6) The engine will start just fine 6 out 10 times when left alone/not attempting to crank.
7) Gas input wont avoid/affect engine stalling.
8) When the engine does starts it does not lack power, it will accelerate fast and crisp, then dies suddenly after 2-8 seconds.
9) The fuel pump can be heard functioning even when the engine refuses to start.
10) The check engine light comes on when key is turned and stays on.
11) Diagnosis E1 + ET1 was attempted on the engine port; The check engine light wont flash, wont turn off, wont do nothing, just stays on. Code retrival was unsusscesful.

What the heck is wrong with this car!!!! Please help!!!!

 

It seems it´s your fuel pump ecu. Do the 12v mod and test again.

 

97 and you are trying to scan the OBD1 way? I thought 1996 is when everything went to OBD II
I would recommend you to use scan tool

 

Is this car OBD II then????? Honestly I did not know!!!! Damn, could've I damaged something else by trying this diagnosis method???!!!!!! OOOPPPPsss

Anyways, I did the 12V fuel pump bypass mod, did not help either... could I've done this mod to OBDII also???!!!! PLEASE TELL ME THIS IS IRRELEVANT!!!

Right now the engine starts maybe for a half a second and then suddenly dies. If the engine remains running for little longer you can press the gas and the engine reponds to it.

 

yeah its odb2, use a scan tool and tell us the code.
Normally a car that fires up and then dies would be a sign of one of the main sensors acting funny as the startup fuel and timing is mostly static so they fire and fall on their face when they start looking at the main map.
we could guess at which one it is (maybe a dirty maf?), but it would make more sense to pull the code with a scan tool.

12v fuel mod is alright, but if it didn't help I would suggest putting it back to stock.
You should only do it if your fuel ecu is bad or if you have major mods, or if you do it the right way with a relay so you don't loose your accident fuel shut off protection.

If you didn't say the power was all there I would also guess ignition, sometimes its hard to tell if its on 4 or 8 when its not started all that long.

 

This might sound stupid, but double check your battery terminal connections. My battery terminal wire was lose and would give me the exact same problem your having. I just got my car a month ago, but the battery tray was gone and my battery was bouncing around. Bought a new tray, tightened the connections, and haven't experienced that problem since. Silly I know, but very possible.

 

Yes I was thinking on returning back to stock the Fuel ECU. I will probabbly leave some connectors just in case I become stranded out there when the car is operational, that way I will be able to bypass the ECU easily.

OK, since the car is not running I requested a scan tool from a friend of mine... let's se what happens.
Meanwhile I'll test check the MAF(like it's shown on thread I saw) and possibly the coils(I dont know how to test them with the engine dead).

Could it be possible for the engine to behave that way with a dirty fuel filter? Can it be that clogged to make this kind of problem? I know I have never change it, possibly neither the two previous owners. The fact is that the car had an empty tank for little over a year when I started the engine again. It now has about 1/2 tank.

Thank's for the support!!!!

 

Jesus dude, tell your friend to stop at autozone and grab you an oil filter. Definitely do some maintenance on the car before taking it for any more spins. A full tune up sounds very necessary for you.

Edit: While you're at it check the air filter situation, how dirty is it? Throw us a picture of your engine bay if you can.

 

I checked the terminals, they all look nice and tight! I'll double check them anyways
Thanks for the suggestion!!!

 

LOL Yes, I definitely had neglected the SC400 My plans are mayor tune-up on this car; New timming belt kit with H20 pump, valve gasket set, new plugs, oil/oil filter, new taillights and new paint job. Everything above except the oil, filters and paint job have been bought/ordered.

I guess the car is mad at me for neglecting him, he is giving me a lesson!!!!

 

I have not worked on many SC's expect my own. Which is a SC3 not a SC4. Anyways, a buddy of mine had a similar problem with his camry, it wouldnt want to idle, if foot was kept on the throttle it would stay alive as soon as you let go and the rpm went down it would die. Not idle at all. I just cleaned his Idler air control valve and this TB and found the air intake tube was torn. So i would recommend you to get some electrical cleaner from any part store and spray on your IAV, throttle body and also on MAF sensor and plug everything back together and see what happens. Good luck!

 

fuel filter

 

I bought a new fuel filter, that has not been installed yet.
Either way I managed to scan the car with a OBDII computer and the verdict was: "Unable to Link" or something like that. Does that mean my ECU is shot?
If try to start the engine right now it will instantly, rev up and everything, but it will suddenly die in about 30-45 seconds.
I have the fuel ecu bypass currently done, could that make the scan return a "Unable to Link" status?

 

not a good sign, try another scan gauge if you can. it should always connect unless the key is in the off position. could be an ecu issue among other things.

 

Forgot to mention, the CEL turns "on" once the engine dies. It also turns "on" when I first turn the key along with all other lights.