Classic ol' not staying running issue.

[Mastathrash]

EDIT: HAVING CODES READ THIS WEEK HOPEFULLY still fires but won't stay started at all.

97 ls400 fires up barley but will not sustain. JJust replaced PCV valve and many vacuum hoses. Prior to the pcv valve replace the it was running. I tested the valve to make sure it was functioning properly and it was..

Everything seems installed and nice and tight and I fixed all the vacuum leaks that I had... I have tried resetting the battery with the fuse pull and the battery method and neither has worked.

I was having severe misses with the engine, But I decided to fix all the vacuum leaks 1st just in case, I had the tubes and it was cheap and easy to do. I Believe this is an electrical issue and not related to the mechanicals (He HOPES!)

Before replaceing the PCV, the car was not missing and was running reasonably and even getting better gas mileage off the/tak than I have in years! So Which stupid sensor or machine God or goddess did I wind up pissing off?!

ANY HELP OR INPUT IS WELCOME I AM NOT a Lexus Mech.

I am about to try to reset the immobilizer and see if that is the issue.
"Edit: didn't work"^^^^

I ALSO I had a hard start that threw a check engine light PRIOR TO THIS ISSUE so I'm hoping nothing is too f'ed up. I wound up driving at home successfully But the only thing I did came home was replaced the PCV valve and it's hose which looks correct and I definitely didn't get any "nasty's" inside.

I've had this car for over a 100000 spirited miles and I'm not ready to give it up yet. I love this car. But I am not ready to pull and learn to rebuild the engine I just don't have the time and money right now.



I am posting this thread in case other people encounter this issue as I've looked through many forums and there doesn't seem to be definitive answers so for better for worse I will post my journey Solving this problem and hopefully it helps somebody else dealing with the same.

 

[Zuffen]

First up, don't go replacing the injectors unless you know they are faulty. This just opens the way for more issues.

You need to methodically approach the problem.

Even having all the vacuum lines mucked up or unplugged the engine would probably start. These things will run well on 4 cylinders.

First thing I would do is see if it has spark at the plugs.

If it does you know you have a fuel issue. If it doesn't follow the ignition system back to the ignitors seeing if you have spark or power in the appropriate places.

If it is fuel you could try a squirt of ether/starter fluid. It should fire a few times and may even run for a few seconds.

If it does try and run, check you have fuel pressure. I find the best way is to crack a fuel union with the ignition on. It should spray a small amount of fuel. If it does spray tighten it back up quick as it is a hazard but it's the only way I know to do it on a 1UZ.

Fuel at the rails and not fueling the engine suggests it may have lost power to the injectors. It also won't fire the injectors if the ECU isn't seeing a spark signal.

Start checking fuses.

I suspect it's a problem around the throttle body as that's the area you would have played in most.

 

[Mastathrash]

Good to know and thank you, I will check these things tonight snd see how it goes

First up, don't go replacing the injectors unless you know they are faulty. This just opens the way for more issues.

You need to methodically approach the problem.

Even having all the vacuum lines mucked up or unplugged the engine would probably start. These things will run well on 4 cylinders.

First thing I would do is see if it has spark at the plugs.

If it does you know you have a fuel issue. If it doesn't follow the ignition system back to the ignitors seeing if you have spark or power in the appropriate places.

If it is fuel you could try a squirt of ether/starter fluid. It should fire a few times and may even run for a few seconds.

If it does try and run, check you have fuel pressure. I find the best way is to crack a fuel union with the ignition on. It should spray a small amount of fuel. If it does spray tighten it back up quick as it is a hazard but it's the only way I know to do it on a 1UZ.

Fuel at the rails and not fueling the engine suggests it may have lost power to the injectors. It also won't fire the injectors if the ECU isn't seeing a spark signal.

Start checking fuses.

I suspect it's a problem around the throttle body as that's the area you would have played in most.

 

[Mastathrash]

Hopefully this week in light of the current rains that are coming to my neck of the woods. Ideally have the codes read by this weekend. I am waiting to do a fuel test With help from our resident experienced mechanic at our shop. If Necessary after the diagnostic. and if not I will simply read the codes myself with the renting of a code reader. (Because I am impatient). I will share the codes and my findings on this issue, I just pray the machine gods that it's a simple

What it seems like is: My car wouldn't start and has spark but does not seem like it's getting the adequate fuel..... And the last thing I changed was the PCV valve and its hose and I did so with great care and cleanliness. It was running decently PRIOR to it throwing an engine code. In high inside it did so immediately after.

I drove at 20 miles from Napa auto parts back to my house and I tried to fire it up again and nothing's doing!

My thoughts are it is an EGR issue or something is shorted somehow. My harness quite frankly does not look very great but I'm banking on the fact that the connections are still made so we're going to go with. It looked fine and ran for years and it's current condition electrically and so that's what baffles me.

I have already replaced all the vacuum hoses including the one to the pcv valve. I am not sure why this could have or would have pissed off my vehicle but it has. Before this issue she was having severe missing issues and I am fearing that it is definitely an electrical issue which is my worst nightmare because I hate doing electrical shit.

First up, don't go replacing the injectors unless you know they are faulty. This just opens the way for more issues.

You need to methodically approach the problem.

Even having all the vacuum lines mucked up or unplugged the engine would probably start. These things will run well on 4 cylinders.

First thing I would do is see if it has spark at the plugs.

If it does you know you have a fuel issue. If it doesn't follow the ignition system back to the ignitors seeing if you have spark or power in the appropriate places.

If it is fuel you could try a squirt of ether/starter fluid. It should fire a few times and may even run for a few seconds.

If it does try and run, check you have fuel pressure. I find the best way is to crack a fuel union with the ignition on. It should spray a small amount of fuel. If it does spray tighten it back up quick as it is a hazard but it's the only way I know to do it on a 1UZ.

Fuel at the rails and not fueling the engine suggests it may have lost power to the injectors. It also won't fire the injectors if the ECU isn't seeing a spark signal.

Start checking fuses.

I suspect it's a problem around the throttle body as that's the area you would have played in most.

Update: the fuses all seem to be intact. And if I can our resident shop guy with mad skills and a code reader this week, with his help will definitely do that fuel test!

I either suspect that it is indeed a throttle body issue or the EGR "sensor" "relay" shittin' the bed or some like that. Please note that I have not cleaned the throttle body or any of its exterior components. This also might be a good course of action to start with if the fuel test and the diagnostic comes up BS.


I will post my findings for science.

 

[Mastathrash]

First up, don't go replacing the injectors unless you know they are faulty. This just opens the way for more issues.

You need to methodically approach the problem.

Even having all the vacuum lines mucked up or unplugged the engine would probably start. These things will run well on 4 cylinders.

First thing I would do is see if it has spark at the plugs.

If it does you know you have a fuel issue. If it doesn't follow the ignition system back to the ignitors seeing if you have spark or power in the appropriate places.

If it is fuel you could try a squirt of ether/starter fluid. It should fire a few times and may even run for a few seconds.

If it does try and run, check you have fuel pressure. I find the best way is to crack a fuel union with the ignition on. It should spray a small amount of fuel. If it does spray tighten it back up quick as it is a hazard but it's the only way I know to do it on a 1UZ.

Fuel at the rails and not fueling the engine suggests it may have lost power to the injectors. It also won't fire the injectors if the ECU isn't seeing a spark signal.

Start checking fuses.

I suspect it's a problem around the throttle body as that's the area you would have played in most.

Also I agree on not going after the injectors 1st! while they are old, they have worked hours prior to this issue with no problem and no noises or weird happenings. I think as you suspect it may be a throttle body cleanliness issue which I will address or it is unfortunately an electrical issue.. I am personally betting and hoping that is a simple fuel issue with maybe the filter being clogged or the EGR being unhappy..ect. I do damn well hate electrical issues, And running wiring like the plague.

 

[Zuffen]

With any issue after you have worked on the engine, try and keep your testing and replacement of parts to what you worked on.

It stands to reason that as it worked before you worked on it the problem will be in the area you worked.

Keep in mind the car is nearly 25 years old and a lot of the electrical plugs and clips will be brittle and easily broken. it would be worth looking at all sensor and loom plugs around where you worked to ensure they are all correctly plugged in. it only takes 1 poor connection to stop it running.

 

[Mastathrash]

With any issue after you have worked on the engine, try and keep your testing and replacement of parts to what you worked on.

It stands to reason that as it worked before you worked on it the problem will be in the area you worked.

Keep in mind the car is nearly 25 years old and a lot of the electrical plugs and clips will be brittle and easily broken. it would be worth looking at all sensor and loom plugs around where you worked to ensure they are all correctly plugged in. it only takes 1 poor connection to stop it running.

CORRECT SIR! AAAND THERE IT WAS. *FACE SLAP* the bugger melted itself while i was asking "why is it missing, ect ect?!" Took some looking but with some help it fixed and running again! Wound up using a Chevy connector (a lot cheaper short term) which was bulky af but solid. I'll take a picture of it later

 

[Zuffen]

At a guess you had a short within that loom.

Electrical tape is useless in engine looms as they get too hot.

Invest in heat shrink and brush up on soldering wires together and you should be able to avoid that happening again.