Stromtroop

Before I start this thread I would like to ask that we stay on topic of this particular topic because I think its important. Specifically I want to focus on the ECU and determine exactly what the ECU does and how failed components within the ECU may effect the performance of the car. Please reframe from throwing random suggestions at me like changing the MAF, O2, Fuel Pressure sensor etc. I am totally aware of these potential issues but a recent scenario I was involved in leads to believe people have possible inadvertently ruled out the ECU as the culprit and moved on... I will elaborate in a minute.

Over the past 3-4 weeks I have read so many threads where LS 400 owners have tried to solve there LS400 "Issues" (Engine light on, Trac Control light on, stalling etc... by swapping out or fixing the ECU with new capacitors only to discover that there problems still exist and have moved on in there diagnostic adventure... changing there MAF, O2 new spark plugs, new leads and have still not been able to solve there problem. My theory is that the ECU (even after capacitor repairs are done) should not be ruled out.

Background: I recently purchased a 1993 LS400 with 140,000 km (86,000 miles) that had been sitting for approx. 5 years. It was absolutely immaculate, however had a thick later of dust, 4 flat tires, dead battery etc. With a new battery, air in the tires it fired right up and I drove it home. The cluster didn't come to life until it was warm, however there were no warning lights on and the car drove perfectly, it didn't stall, it didn't sputter, the transmission was smooth etc. But as I got a feel for the car I realized it lacked power and acceleration. I hadn't initially noticed because I had not really given the car any hard driving. When I started to focus on that, it became very apparent something was wrong. If I pressed on the gas pedal it would only lumber up to speed - And as day 1 day turned into day 3, I noticed something else - I had emptied a full tank of premium gas and had only gone 200 km. (125 miles).

It was at this point in time I started to read about Lexus LS400 (on this forum) and the leaky capacitor issues that have plagued these cars. My car was not experiencing the problems described by many. I did not have a service engine light on, Trac control light, my car wasn't stalling etc. It was just under performing.

After removing my ECU and observing several leaking capacitors I opted to obtain a refurbished one instead of sending mine for repairs. I ordered an ECU from Flagship 1 and upon receiving it I couldn't help myself but to break the warranty seal to examine the inside. I observed that every capacitor had been replaced and the solder joints looked great, I also noticed the remnants of brown capacitor fluid that had been cleaned from the board. After my inspection of the unit I installed it on my car and drove it around the block. Within 100 feet of driving my service engine light came on, Trac light came on, the car started to stall and sputter. I limped it home and Immediately put my old ECU back in. It ran just as "good" as it had before.

I thought this was very interesting, I was able to determine that a professionally refurbished ECU with brand new capacitors was faulty. And I couldn't help but to think how many people have gone down this path. How many LS400 owners have installed a refurbished ECU and have experienced no change in there car's performance. These owners may come to one of two conclusions.

1. The refurbished ECU was bad and I still need to examine this issues, or;
2. Since I have installed a refurbished ECU and I still have issues, it must be something else.

When the latter is concluded more money is then spent on trying to fix all of sorts of other components that most likely do not need to be fixed or replaced.

I would like to stick with conclusion 1. a refurbished or repaired ECU can still be bad. So here is what I would like to know, what do each of the components do - what do the capacitors do, what do the micro chips do etc. How does the failure of any one of the capacitor effect the performance, or cause the problems that they do. (AND PLEASE FOR THE PURPOSE OF THIS DISCUSION, LETS ASSUME THE REST OF THE COMPONENTS OF THE CAR ARE FINE).

I welcome your thoughts and opinions. By promoting an ECU specific discussion I'm hoping to educate myself on how the ECU functions in its relationship to the car's performance and faults, and possibly help someone get there old LS400 running again. (50 years ago I would be promoting discussion about a specific component of a new fancy carburetor... but here I am trying to understand 27 year old computer technology instead)

One last comment - I am aware of the threads related to Flagship 1, and I'm not posting this thread to engage in a discussion on how bad, good or neutral the feedback is. I was aware of all feedback when I opted to purchase from them. This was an informed decision that I made because I didn't want to send out my one and only ECU . But more to my point, even after refurbishment (new caps) it still failed - and this is precisely why I'm starting this thread.

Yamae

You should have checked this before the action.
https://www.sitejabber.com/reviews/fs1inc.com

It says as follows.
Flagship One Inc has a consumer rating of 2.05 stars from 253 reviews indicating that most customers are generally dissatisfied with their purchases. Consumers complaining about Flagship One Inc most frequently mention customer service, account manager and tracking number problems. Flagship One Inc ranks 171st among Auto Parts sites.

My only recommendation is to be refurbished by Denso or do it all by yourself.

YODAONE

What is P.N. of original and replacement ECU?

Stored codes?

Why was vehicle "stored"?

RA40

iTrader: (6)

What were the CEL codes? I would also be curious why a well running car would go into storage mode. That often indicates some difficult to resolve issue that the owner will come back to later. Later doesn't come though.

Were the capacitors the proper spec? The PCB on the refurbished units may still be bad causing similar problems even if the capacitors have been replaced. Getting the ECU working right is a starting point. Many of them have age related issues to deal with like other aged sensors that the ECU relies on. One other external factor may be rodent damage if they've munched on wiring insulators.

Stromtroop

First things first... sorry for the incorrect reply to YODAONE, I'm new to this forum format and erroneously sent entire initial threat as my reply.

And for you RA40, the car was in dry storage due to an estate situation. It had all service records for every oil change since leaving the showroom, and by reading all records (in the glove box) I confirmed it had only been driven 5,000 km (3000 miles) per year. There was also a receipt from Costco showing the tires were installed in 2010 and the odometer was recorded by Costco as 125,000. The oil change sticker in the window read 146,900 or Dec 10 2015. At the time of my purchase the odometer read 146,500. So I believe the car was parked Late 2015. It was a time capsule, paper maps were in the doors, and the tape deck was still playing Johnny Cash! It is my opinion that the car was simply not driven due to the estate / probate period and had nothing to do with the vehicle. No codes were ever obtained by me as my mechanic does not have an old enough tester. I have only had the car for 1 month... and I can confirm that no rodents have chewed any wires. I have had the car on a hoist and looked over everything.

I hope my next comments don't come off as argumentative or rude (I sincerely don't mean to). I don't disagree that my refurbished board still has problems, and I am confident (hopeful) that sending my original ECU to a very reputable Lexus ECU engineer will solve my problems. (I'll add the ECU number later, they are not handy at the moments) I also totally agree that getting the ECU working right is the starting point having. You are also correct when you say that as the ECU ages they experience age related issues. This is precisely the point I want to explore.

By now we can all agree that over time, Lexus ECU's will have leaky capacitors. But what else does age effect within the ECU and how do all of these cumulative problems ultimately affect performance. Please continue this thread with these questions in mind.

How does age effect ALL of the components of the ECU. With respect to the caps, we can all agree that over time they will leak. For my car, I would like to know how did (does) those leaking capacitors effect the performance of the car over time. When they started to leak, the capacitance of each capacitor would have changed ever so slowly over time, and I'll bet so too did the performance, however I suspect so unremarkably slow that the previous owner did not notice over the 22 years he drove his car. And while all of these changes were occurring, the sensors would have been providing feedback in a loop back to the ECU and electrical components would have compensated to keep the car running... correct? However eventually the capacitance will change to such a marked degree that other components can not compensate enough and the car will eventually stall and exhibit other issues... correct? The obvious solution to this problem is to remove and replace leaky bad caps with new ones.

But (for discussion) what happens when new (proper spec) capacitors are installed (correctly) and the problems still exist. I think its erroneous to simply conclude that the job was done wrong, or that replacement caps were the wrong spec, etc. There just as many people with success stories as there are with continues problems. What else can we look at within the ECU as a potential casualty of time?

If it the consensus of the forum participants that the only bad part of the LS400 ECU'S are the capacitors, and when replaced correctly the ECU's will operate perfectly then I will stand down. But if anyone agrees that we should be looking at other components (and any examples with success stories) then I would love this thread to continue.

RA40

iTrader: (6)

Good, sounds like they cared for this one.

This may be of interest:
https://www.clublexus.com/forums/ls-...read-this.html
https://www.clublexus.com/forums/ls-...ange-pics.html

mrmox

I learned in school there are just 4 types of components: R, L, C, and let's say T for transistors (mostly inside chips).
R,L and T have NO WEAR MECHANISMS to speak of (they are subject to differential thermal expansion hazards but I do not think of that as a wear mechanism).
C however, if they contain a liquid electrolyte, will be used up over time by doing their job (smoothing voltage mostly).
If the electrolyte is DEFECTIVE the C will fail quicker, as happened in the case of the stolen incomplete formula you can read about on Wikipedia.
At least that's the way I remember it!

Yamae

I found that the OP Stromtroop concluded posting this writing,"It became clear to me that bad capacitors in the ECU were a likely culprit. I never would have thought to consider this!". Just like as mrmox wrote,"If the electrolyte is DEFECTIVE the C will fail quicker". LS400s and Celsiors up to UCF20/21 use those infamous electrolytic capacitors that contain quaternary ammonium salt. Those fail faster than conventional electrolytic capacitors, I must add.