I've been doing some work to this poor old machine of mine, 93 SC400, 254k miles
I have most recently done the timing belt - https://www.clublexus.com/forums/per...ion-sc400.html

It still won't start
So thinking its an electrical issue (most of the time it has been), I checked the cam and crank sensors
they're good and in the middle of the spec
I checked for coil fire - they're firing
I know its getting fuel because I can smell it and the plugs are wet - I pulled them to do a compression check
The cams and crank are still in alignment
Here's the strange part I don't get -
Back in Nov of 14, when this problem happened, I did a compression check
I got between 190 to 200 bls across all cylinders - no big deal
The vehicle has sat ever since - I haven't had it near me to work on it until recently

Today the compression check yields 110 to 120 lbs on the left bank
0 on the right bank - nothing, nada, zilch - on all 4 cylinders - the guage didn't even bounce


I pulled the right valve cover, all appears normal - no signs of damage, wiped cams or destroyed gears
The cams rotate with rotation of the crank
The lifters move up and down like they should
With all the plugs removed, I feel the cylinders moving air when turning the starter

What's going on here?

Just some back story - when this 'problem' occurred, I had put some gas in it, was pulling away from the pump and the car lurched, sputtered and died - I got it started and back to the house, it was running like garbage - In the process of working this problem, I have replaced all the ignition components from rotors to plugs with new - It was running before I did the timing belt, but wasn't firing on cylinders 2, 3 & 5 (driven from the right dist) - I verified this when I pulled the new plugs to do the compression check back in Nov of 14
Before this problem happened, it was running like a damn champ
I wouldn't hesitate to put it up next a rustang GT
It would put you back in the seat by simply putting the pedal to the floor

Help!?

 

ECU probably crapped itself. Do a search for "ecu capacitors" as it's a common problem.

 

according to your other thread, the cams were 90 degrees out of alignment, is this when you did the first compression test where you got 190? or was it after you had fixed the cams you got 190? or was the 190 entirely before all of that? I cant figure it out

if its before you fixed it then fixing it could have caused it to not show compression now. if someone messed it up that bad, maybe they messed up the alignment of the intake cam and exhaust cam gears inside the valvecover also... either that or your motor is the kind that is interference but you said its original so lets assume its not... the chances of having 4 valves go bad at once or a blown headgasket showing all 4 as zero is low, so I think its a cam issue or alignment issue, are you sure you aligned it right, as in the crank is at TDC with the cams aligned cause its possible to have the crank 1 rotation out and if you were misaligned in the first place you are likely to have it wrong if you don't physically check cylinder 1 is at tdc. You might be able to confirm on a distributor car that the rotor for plug 1 is pointing at plug 1 since its non adjustable on that car, that might give you an idea although I am not 100% on that.

 

If the ECU went south, it wouldn't be firing

 

Q1 - Yes, the cams were about 90deg out from the crank, they were still lined up with each other, they both lagged the crank
Q2 - After I changed the timing belt, I got half compression on the d/s, 0 on the p/s
Q3 - before this happened, it ran like a damn champ

I've been thinking about this for a week now
Its got to be a mechanical timing issue - like the crank gear to the timing belt
nothing else would give these results i've gotten
Yes, this is one of the clearance motors, original 93 - thank God
I'll be tearing back into it this week

 

if it was running like a champ before then I would think that it was actually not out of alignment, its hard to jump teeth on these motors unless the tensioner has fully failed.
there are also a few lines on the crank pulley, and I want to say 2 notches on the block or lining up, one is actually tdc, and one is the service position where the valves are not pushing against the cam so you can release the intake and exhaust cams together safely without them springing up at you, and also how you install them. if not paying attention its easy to line this motor up incorrectly. go back through it with the manual and check all the dots. also the lines on the belt itself only work for the first time you install the belt, the first turn of the motor the lines on the belt will not align up again until many many revolutions, so you have to go by the marks on the block for the crank and the marks on the covers for the cams... the correct marks, I think there is a notch and a "T" mark for the cams. I did it on a 2uz before but I think the 1uz is very similar.

 

I'm thinking that's exactly what happened - the belt I've removed with only 10k on it came in a kit that didn't have one in it - DUH on me

Yea, I noticed that

 

Just to update in case anyone else has these problems -

I was aligning the cams incorrectly
I was lining up the cams using the tabs on the BACK of the cam gears
The correct cam gear marks to use are on the FRONT of the cam gears, marks I cant say I remember last time
Once I did this, the rotors aligned with some marks on the dist cap/cam sensor housings

Other than a high idle issue, she's back to running like a champ again!

 

Where are you in MS? Might be able to share notes, etc if you are close. Message me if you would rather.

 

Hernando - right close to Memphis Tn