Thatguybob

I have a 1994 ls400 and I’m having trouble with it staying on and starting I bought it not running been sitting for a while i replaced the fuel pump and fuel filter and new gas i tightened the throttled to get it to stay on and it will stay on but misfiring . when I give it some gas there feel like there is a restriction in the throttle body it starts like choking up when accelerating and dies I tried to drive it and it won’t go over 2k rpm what could it be

deanshark

Buying a non-running car is always a crapshoot. Your condition could be a number of things. But with your description it sounds like a very bad skip, which could be a timing issue. (timing belt jumped) Could be a bad coil. (running only on 4 cylinders)
Or, 9 out of 10 people will tell you, ECU; https://www.clublexus.com/forums/ls-...capacitor.html
Do you have any service history on the car, was something done to it by the previous owner which caused him to just park it and not fix it? How many miles?
This has nothing to do with a diagnosis but we all like to know; how much ya pay for it?

Thatguybob

They parked it and and where going to restore it but lost interest they said it was the fuel pump they said before that in ran fine and it’s been sitting for a couple years. when I changed the fuel pump to the newer one the old sock was so dirty and falling apart I put some sea-foam last night and new spark plugs and it was starting up every 2nd crank it and it’s also misfiring it I haven’t cleaned the injectors yet and I bought it for 1100 it has a lil crash and it mostly only broke the head light and it’s like a 140000

deanshark

That's a good price, for something to work on. As long as you have the time, and knowledge.
Have you checked for any codes? That can point ya in the right direction. If the ECU isn't sending any communication to the engine light, then you have a bad ECU. I would still check the timing marks to see if they all line up together.
This will show you the timing marks and where they are supposed to be; http://www.lexls.com/tutorials/engine/timingbelt.html
Check out all his tutorials, there's alot of info good there.

Thatguybob

No I haven’t read the codes I wanted to try to hook up my obd to it but I don’t have the adapter. it just something I work on after work I’m thing on counting the codes today and cleaning the injectors it dose have a check engine light do u have a messenger so we can communicate easy and faster

deanshark

You're better off posting everything here so much more people will read it, and there will be, much more. Different minds will pop on at different times. It's good to have many different points of view, not just one.
Here's the numbers for the OBD1 codes; http://www.lexls.com/tutorials/intro/codereading.html

Thatguybob

It’s not reading the codes dose that mean it’s the ecu

paulo57509

If you haven't done so yet, please review:

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

deanshark

More then likely.
If there are no codes stored then the light will blink continuously, every .25 second. If the light stays on solid with no blinks then there's no communication with ECU.
The ECU is a very well known problem, meaning if it's not bad yet, it will be soon.
Do you have any other symptoms listed in the ECU link I posted?
When I was having alot of those symptoms on my old 93 I was thick headed and didn't want to believe that was my problem, but when I changed the ECU everything turned out good so now I'm a true believer.

CELSI0R

Which method did you try to read the codes? If you're using an OBD-II scan tool with an adapter, it will not work and this doesn't mean the ECU is bad.

It's best to use the method deanshark mentioned for checking codes.

I just posted about this here -
https://www.clublexus.com/forums/ls-...l#post11421993

A misfire could still be an air, fuel, or spark issue. You may need to check everything from vacuum lines, to cylinder compression, igniters, coils, plugs, plug wires, distributors, fuel injectors, etc. And I don't mean replacing all of these parts because what you might put on could be worse than what's on the car. It is also possible that the ECU is bad, but there are too many variables to say whether if that's the culprit or not right now. However, I would also review the info deanshark shared on the ECU. It's a good point that capacitor failure in the module could cause a variety of problems.

To see if the problem is related to ignition, I would suggest doing a cylinder drop test.

If you are learning, I would consider talking to a mechanic who has worked on older cars. The basic diagnostic steps between OBD-I and modern OBD-II cars are very similar, if not the same, but OBD-I often will not point you directly where to look for each issue, and instead will give you an idea of which systems in the car are problematic and require diagnosis.

Thatguybob

Yes I had a good amount of the symptoms from the ecu link I just ordered a new ecu

CELSI0R

I would try a few tests first before changing the ECU. It's not guaranteed that the ECU is actually your problem right now, but definitely good to review the symptoms to see the overlap

I would suggest to do a cylinder drop test with your current ECU before changing any parts.

Swapping out more parts on the car without testing will only complicate the issue as there are more variables being added into the mix