Hello, this is my fist post here. I drive a 1990 LS400.
Here is the story. My car in the past has ran great I've kept up with maintenance and only had to repair small things here and there. So one afternoon I got in my car started up fine and jumped a light going pretty fast (on cold engine) and when I let off the gas it was running very bad like a misfire or something else. I immediately took it to my garage and starting troubleshooting. After a little looking I noticed my drivers side cam gear was off about 2 teeth so I figured this is the problem and it probably was. So I started dissasembling and after 2 days of work on that and getting the crank at TDC and cams lined up with the back plates I put it all back together. During this job I also replaced all 8 spark plugs and ignition rotors. After assembling everything together when I try to crank it it will try to crank but won't start. Also will backfire smoke out the intake which doesn't seem correct. I removed covers again to double check firing order and check if the timing notches all line up and look about half a tooth off very slight. But still should turn over and run even like that just not perfect. Very lost at this point and some help would really be appreciated. This car is my daily and without it I am screwed so any help at all will be help.

 

Check all leads for spark. Also double check the connection to your ignition coils. If you are getting smoke you have fuel so it sounds ignition related.

 

Could there still be something wrong with timing. Distributors worked fine before removal. But I could be wrong. Something is very wrong for it to be shooting flames out the ignition.

 

Ignition Timing is off.
I don't know this engine but if it has a dizzy you have to time it properly so that while at TDC, the rotor and cap point to cyl#1 plug wire(s).
i.e. engine on TDC #1 (All valves for that hole closed and that hole is building compression), now as you drop the dizzy in, confirm the rotor is pointed to cylinder #1 electrode on the cap and that lead goes to cylinder #1.
If the distributor can be adjusted (rotated) try advancing it as it sounds to be firing so late the intake valves are open and the piston is headed down the bore.

Good luck...

Usually the dizzy driver is

 

Did you put the rotor back to the shaft properly? I imagine that it's 180 degrees off.

 

If flames are coming out the intake then it's timing. It means that a combustion isn't sealed and it's exploding before compression. Either timing belt or a cap and rotor is on wrong

 

Thanks for all the advice. I was looking on Lexls.com to check the rotors going on the right way but I could be wrong I will make sure i would feel real dumb if they were facing 180 degrees. I will make sure they are pointed to the first firing wire on each dustributor cap. Is there a way to check which position the piston is in to make sure it's firing in the right spot.

 

Also is there a way that the camshafts could be on the wrong rotation for the crank. The crank goes 2 revolutions around every time both the camshafts line up. So is it possible they could be on the wrong rotation of the crank. Maybe this would cause it all to be on the wrong rotation even with them all on TDC. Maybe I'm wrong just a guess.

 

You probably know better than we do about what exactly you moved on the car. I agree it sounds like ignition is out of sync, which could easily be done by installing the rotors wrong.

The cams, crank, and ignition all need to be synched. Easy to do, but also easy to do wrong. ;-) The good thing in your favor is having the Gen1 non-interference engine so you're not going to be causing engine damage if the cam-crank timing is off.

 

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did some more researching what I could have done wrong and I had been using Lexls.com tutorial on timing belt and on the pictures for the rotors that is shows the metal on the ignition rotor on drivers side cam is facing towards plug 6 on distributor when that is 180 degrees from 1. If this is the case these pictures are misleading because it looks all lined up at top dead center. Will take a look on my own car later to see if this is the problem.

 

I am with Yamae, backfire means MISfire

 

UPDATE: car is running great now. The ignition rotors were one 180 degrees. This was for sure the problem causing the no start and backfire. Thanks for all the help guys. And it seems to be the case the tutorial for timing belt on Lexls.com has the rotors on the wrong way, hopefully nobody else uses them and makes the same mistake I did. Everything else on there is very helpful and seems to be correct. Thanks guys, back to driving my Lexus again.

 

Thanks for the update. I'm glad that you succeeded to fix it.