BobSmith00

EDIT: Thank you to whoever moved the block of posts out of the main ecu thread into my own.

Ok here is some more backstory for those following along at home and were sort lost and confused...

I have a 1996 LS400. Its been a quality car for the about 14 months I've owned it, but granted for 2 of those 14 months, the car has not moved under its own power. I've pushed it, pulled it, towed it, wenched it the only ground it has traveled since Late-Mid May.

Well Let me run down a few things, and see if anyone agrees the ECU Leaking Capacitors could be to blame...
1) Sometimes the speedometer hangs out at zero when starting car, a brief but brisk tapping action would make it come to life, other times it came up on its own. Not sure if I've ever noticed it with the tachometer.
2) At times when first starting car, would go into Reverse and move back as expected, but any forward gear would just not go, and just hang out for a few brief to longer moments before going.
3) Headlights Dimming sometimes at night, a bit of a flicker to them.
4) Battery not charging, but alternator testing good at partshouse.
5) Car starts but dies instantly due to no fuel.

Here is a little more on whats going on. I drove to town about 14 miles a couple weekends ago, car did fine.. Went to start the car up after shopping, car seemed to be only at like half power, then I noticed the AC wasn't blowing all that hard, and then dash lights were dimming before going dark, and the car died. I hit the battery with a multimeter and saw it was way low. Let it sit a bit, it got back up to 12.58 V, and car started up just fine. But a check of the battery with the meter saw the battery steadily going down. Until it reached a voltage too low to operate the car. Got it back to the house, took off the alternator since well that is what I thought was the issue. Had it checked twice, both times it said it passed.

Put that alternator back on, tried a different battery. Car was strong and seemed to be doing fine. But after driving a bit it started losing power, but I had a spare battery with me so I got back home.
Talked to a wise older fella that said it likely was still the alternator, so I picked up a rebuilt alternator. Went to get the car up on the ramps to do the work. And as I was lining up the car with the ramps, it went dead. I thought at first it was just the battery was getting drained so I let it sit a bit, and tried again. It starts but dies instantly, I suspect because it is not getting any gas. That was yesterday, it was storming a good bit of the day today so I didn't get to mess with it, but I tried to source information

No sort of catastrophic thing happened that I'm aware, I drove the car about 200 Miles, then it set for a couple days, I drove it about 14 miles and that is when it went dead the first time. Oil got changed a few days before I drove it the 200ish miles. Filled up the tank on my travels, and I still have 3/4ths of a tank, but as best I can tell none is getting to where it needs to be.

At this point I purchased and ODBII reader, and of course had no codes because if you pull the battery for awhile the codes magically vanish like cookies it seems.

Here is a video of what it is doing, ignore my umbrella, ella, ella, a
I pulled my ecu, and found I have version number
Attachment 499689

And then the below happened. So now you should be caught up.


Well I decided at best to cover the bases and make sure it wasn't something simple as a relay or the fuel pump, or maf, etc.

So I've tested lots, and everything checks out. Replaced the MAF, replaced the Alternator, Replaced Relays, Took out the backseat to check voltage at the Fuel Pump, etc etc.

Everything I've done comes back as should work.
So Later today the cap work will be done, and I'll be at my wits end if the car doesn't come to life afterwards.

LScowboyLS

double check polarity and cap values/placement on all installed caps (you did use the exact ones in my links, right?)

make sure the negative battery cable is disconnected when you go to reconnect the ECU connections

after installing ECU and reconnecting negative battery cable, put key in an don't start vehicle yet, but just turn ignition to RUN position for at least a minute, to give the new caps time to charge up and get to know their new home!

BobSmith00

Got the Right Caps from DigiKey.
Will Make sure the solderer is aware to be mindful of the +/- and Location.

Battery Cable was removed prior to removal.

Will do the hold pattern on Run for a few minutes before attempting to crank.

Good Luck to me.

Will hopefully report back later tonight.

LScowboyLS

I don't mean to imply that you or your solderer are not very sharp or competent, but even the best guys in the world can have a momentary lapse and let a capacitor slip into place backwards polarity, or accidentally get the wrong cap in the wrong spot - it is not a paint by numbers set, there is no "the 47uf one goes here" printed on the circuit board, so very easy to make a little boo-boo!

I sit back and quadruple check everything after finishing a project like this, it even helps to get a second opinion from someone who has not been staring at it for 2 hours!

BobSmith00

Ok, I need some info right quick...
I have a 96.
First post says
Then Says:
Which I ordered 2 of.
Now I ordered this one vs the 63v, is this a failure on my part, because I read "the best is the" and ordered it vs the actual 63v.


Same with
I got that one vs an actual 10v as was in the ecu, but looking at the list of recommended, I dont see a 10v. So I'm guessing its ok if the V is higher?


Same with the last one.

So Did I screw up buying the ones with the V being different than the stock ones?

LScowboyLS

any of the caps listed using the link in my recommended section are great capacitors

most are higher voltage than the originals (the original values are in the list of the 6 caps from the factory)

higher voltage ratings are a GOOD thing! - it enables us to get an even lower ESR and a higher ripple rejection than the original!

sounds like you get an A+ on your ordering!

you must have ordered this a while back, it is my favorite in 47uF and currently sold out until mid September!

BobSmith00

Well Bad news/Good news.

1) Good news is got the caps changed, out, work looked good. Got it put back in the car, and then reconnected the battery. Turned the key to run for a few minutes.

2) Bad news: It's doing the same thing as it was in that video I posted.

I've taken the battery out, to put in the charger thinking maybe it got too weak, but I doubt that.
It seems like my demon is elsewhere.
I feel pretty defeated.

LScowboyLS

you are not defeated at all - this job needed to be done proactively, to head off all of the nightmare intermittent issues that so many other people are having here on Club Lexus!

you just have an additional issue we need to pin down, and these cars are just not that complex really, so we will get to the bottom of it!

disconnect the negative battery cable for the night, and then tomorrow reconnect it, get it to crank using starting fluid (a 2 second spray into the intake near the battery), and then drive it if possible and come back and scan for new codes!

any LS issue can be figured out!

(and get some hood lifts at advance auto or online - that umbrella looks ghetto!)

BobSmith00

It won't stay running with starting fluid. It only functions until the starting fluid is burned up.

The hood lifts is on the about 2 page list of things to do to/for/with the car. Along with replace the drivers door, get it repainted etc. But all of those things for now are by the wayside, for the car is currently just a big paperweight.

LScowboyLS

well besides getting a fresh set of codes, how about let's go back to basics:

how old is the gas in this car? days? week? months? - how much gas is in it?
if you pull a spark plug, is there a gassy smell and look, or is it bone dry?

do you happen to have a fuel pressure gauge set? (even Harbor Freight cheapie is fine)

if you were to pulse a steady stream of starting fluid, could you get it to run longer, like run as long as it is getting the blasts of starting fluid? - if so, then it is a fuel delivery issue, and that will really narrow down and help us zero in on the culprit

also, locate some T-pins at a hobby shop or craft store (very cheap, a whole box is like $2)
and then do the test at the 5:53 mark in this video and report back (this will test most of the electricals - parts of the ECU, the coils, the igniters, and associated wiring)

we have to determine if it is quickly losing fuel or quickly losing spark, or if the correct cam/valve timing or ignition timing has become lost

the other diagnostic is that we need to reinspect the timing belt and it's alignment

here is the video for the basic electrical pulsing:

Yamae

I suggest you to bypass the "Circuit Opening Relay " indicated in the circuit diagram here.

The "Circuit Opening Relay " works when the ECU detects something unusual and stops the fuel pump to work. Bypassing it can be done by shot-circuiting the terminal "5" and "3" and this enables the fuel pump to keep running and the engine might runs longer than before.

This is just to check whether the ECU is inhibiting to continue to run the engine or not. So don't bypass the terminal "5" and "3" for too long. The purpose of the bypassing is just to check and confirm that the ECU is detecting something unusual and stops the engine. If the engine keeps running after the bypassing, it simply means that the ECU disables the fuel pump to run.

I wrote the link above when a 98 LS400 was behaving the same symptom as yours. That LS400 caused the problem when the MAF sensor was not connected. Yours is not a 98 and the ECU is different but the fuel pump circuits are just the same. Also the conditions to stop the fuel pump are a bit different.

Anyway try the bypassing and inform me the result.

BobSmith00

Basics I can sorta handle, still not a mechanic and only have limited knowledge and not a stocked shop of tools.


I filled up the car two days before the alternator seemed to go bad, which was may 20thish. Its close to half a tank full

I will do this and report back.

I do, BUT the huge* is that its intended to be used with a schrader valve and as best I can tell these LS400s need some sort of banjo bolt set up? If you know of the correct Harbor Freight one, some direction will be accepted.

I had it going about 7 seconds off a rag doused in gas by the intake , I assume it only stopped due to the richness being too lean, or rather having used up the fumes or whatever

This is another will have to report back on

Speaking of this, I found this just minutes ago via google http://www.justanswer.com/lexus/634i...ill-start.html Sounds maybe promising?

Have watched this video before, will try it out Wed. assuming weather holds out and report back.
Talked to a few Lexus specialists around the country today, and the two ideas that seemed most prevalent:
1) Idle Air Control Valve
2) Throttle Body

That one of them (or both) could be in need of cleaning or replacement.

I am very grateful for the help, I am doing for the most part the best I can, the weather and everything else is not co-operating so much.

BobSmith00

I just have seen your post, I am going outside to try this, and will report back shortly the results. Again thank you for your thoughts.

nismo4life

I know you're probably going to say my issue is my capacitors, but just humor me Cowboy!


The car will do this intermittently. Temperature doesn't seem to effect it, its not bad or old gas, or specific gas because I have put fuel from 3 different stations in it always using 93. I have checked the MAF, coil, CTS, and alternator with a multimeter according to the FSM and all seem to be properly working. For what its worth the car is only running 13.42 volts while idle. My friends told me it should be running at least 14, but we tested the alternator and it is putting out 95 amps (rated 100). The car will do this completely randomly if at all. I haven't driven it too much after the 5spd swap, but for what its worth it was not doing it prior to being parked. I have no check engine light or codes, and the last time I got it to do the issue I let it idle waiting for my buddy to come by to check it out, and it randomly stopped doing it and revved fine. Above 3k the car seems to be fine, though my friend Ben said that's because he thinks the car goes into closed loop. I've ran seafoam through it, changed the fuel filter, car has all new fluids, and there are no vacuum leaks. Any ideas?

LScowboyLS

no, it sounds like someone who knows very little about the LS400


listen to Yamae - he is the world-class expert on LS400