Oldschl400

Newb here hoping to get some thoughts and opinions. I have a 2000 LS 400 with about 167k on the clock. The car has pretty much been trouble free until recently. I just took it to my mechanic and had the timing belt, motor mounts and all seals replaced in the motor. Once I got it back, the car was running smooth as glass. About a week after all the maintenance was done, I was driving in some rain and gassed it to pass another car and the back wheels spun and engine revved up pretty high. Nothing out of the ordinary, just lost traction. No CEL came on or anything at that specific point and time. However, later that day I started the car and all of the sudden the CEL and VSC off lights came on. I tried turning the car on and off several times and disconnecting the battery but the lights would return. Car still ran smooth and really showed no signs of any issue. No weird sounds or smells or driveability issues, just the lights. I took it to get it checked out and it was an OCV sensor code on bank 1. I took it to the mechanic who did the work hoping maybe the sensor was loose or there was something else he could find. He replaced the sensor with a used one he had laying around but this did not correct the issue. He asked me to drive the car for a week or so and see if it cleared or got worse. Well, things got worse. After driving the car around for a while, it would begin to run rough in spots and at red lights it would idle rough and the CEL and VSC lights would begin to flash. So we decided to get a brand new OCV for that bank to see if that would correct the issue. Doing that brought on even more issues. We began getting the same OCV code and now a misfire on cylinder 6. All of these issues were all on the passenger side of the motor. Running through the diagnostic manual, he ruled out pretty much everything except for the ECU or the Cam actuator. We decided to have the ECU repaired. I shipped it off to lscowboyls and got it back in a couple of days. After reinstalling the ECU, the car began misfiring on several cylinders on bank 1 and continued to throw the OCV code. So the last part to throw at this was the Cam actuator. Sourced a new one from a Lexus dealer and installed it. The car started up and ran fine for a few minutes and then began to,surge and the mechanic shut it off to check the codes. Now he cannot pull any codes and the car will not crank at all. He said it just turns over but that's it. I am pretty much at wits end with what to do. This seems to be electrical or ECU related to me. I am hoping someone has possibly gone through something of this nature and can give me some good advice. I wonder if I need to try and locate a mechanic who knows these cars really,well. The mechanic I am using is a Toyota Master mechanic so I'm not sure changing mechanics will benefit me. But sometimes a second opinion is what you need. He is pretty sure the ECU is the culprit and it's hard for me to disagree. But the car never had any weird ECU issues in the past. I've owned the car for 8 years and my dad had it before me. The car is really in excellent shape motor wise, except for the gremlins that have now crept in Even the mechanic is saying it is very well taken care of. All the internals look brand new. Anyway, if anyone has thoughts or opinions on what else I can do, I would very much appreciate it. I love this car, but I am having a hell of a time trying to get it back running good.

Moarpower

Unfortunately it is as you say, a gremlin. It could be the ecu or thing between it and the source that the trouble codes lead you too. To be honest all you can do is start at the cheapest thing and work your way up hoping that you don't replace the whole car in the process.

Start by sourcing a used working ecu and seeing if it works. Head to a junk yard and see if you can try before you buy.

fixmiester

It may be a huge coincidence, but the only pattern I see here is that every time your mechanic touches the car, more problems pop up. That can happen with older cars that have brittle wiring, corroded connectors, etc., but yours seems to be an extreme case. May be time for a different "expert mechanic". Someone with a scope needs to look at the ECU signals, at a minimum.

Oldschl400

Yeah I sort of have the same feeling. I am starting to think I might need a second opinion. I still hope some more folks chime in on this. Thanks for the replies.

YODAONE

How do you know the OCV the mechanic had "laying around" was any good?? A defective part from another car? (Does it rattle when you shake iy?)

Did the used OCV alleviate the trouble code?

Suggest OEM OCV's be replaced in pairs.

The mechanic may also have fractured wiring.

If able, Check with voltmeter/ohm meter.

Also check cam position sensor, crank position sensor and wiring...

Some mechanics tend to rip at wiring when frustrated..

check all related components disrupted by timing belt change for resistance and wiring for continuity.

Make sure the crank position sensor wiring was properly routed and clamped so not abraded by serpentine belt.

The ECU probably was not the problem

Oldschl400

How do you know the OCV the mechanic had "laying around" was any good?? A defective part from another car? (Does it rattle when you shake it? He made sure it wasn't seized and also ran 12 volts through it to manually test the action. The original part as well as the spare part both exhibited proper behavior.

Did the used OCV alleviate the trouble code? No

Suggest OEM OCV's be replaced in pairs. A brand new OEM part was installed on the bank with the issue. Do I need to get one for the other side too?

timmy0tool

iTrader: (7)

whenever I get misfires from Toyota motors I always replace the spark plugs first. it would be worth a quick check to see if all the plug wires are properly seated as well.

dicer

So what could rain get on or in to make it run badly? Maybe something electrical is not tight or a ground is a bit corroded and just picked this time to mess things up.
2000LS ? CAN system, the tech that works on the car needs a top of the line scan tool and with that he or she could have checked that part that was replaced before condemning it. The scan tool is going to find the problem or at least get the tech very close to it. Toyota master tech? The tech should know its not the old "I think its this" world anymore, its connect the computer and start looking for the problem world now.

Yamae

I worry that those 2 problems are often caused by a skipped timing belt. I'd check the timing belt properly aligned and has proper tension.

dicer

I kinda thought that as well, but he said it was smooth after the work. Unless the tensioner was not released or ?

Oldschl400

The motor runs smooth as glass intermittently. For example, when he replaced the Cam actuator, it ran perfect for about 5-10 min. Then threw a code, and now we cannot get the motor to start. It only turns over. Additionally we cannot get a code from the scan tool. This seems to indicate the ECU is problematic.

Oldschl400

By the way, how involved is sourcing a used ECU and transferring it to my car?

lexslexus

Not sure if you're in the Atlanta area but if so, I highly recommend ToyoTechs on Clairmont Road for a second opinion. They know how to fix the type of issue that you're running into. Diagnosis is free so it couldn't hurt to give them a try.

dicer

The newer cars ECU's have to be programmed to the system and keys etc. You WILL NOT BE LOOKING FOR A CODE, WHEN USING A SCAN TOOL.
Your looking for data and looking to control things that can be controlled with the tool, ie testing them, and signals.
If all that is being done is looking for codes, then you do not have a proper scan tool, nor the proper person using it. A true high end scan tool does way more than just read codes. Reading codes can be done with a $30. code reader, a good scan tool starts at about $1000. and goes up to $20,000 or more. So which one does he or you have?
Your not going to guess what is going on with the CAN system, you need someone that knows that stuff and has the proper tools for it.

Oldschl400

Thanks for the info. I will look them up for sure.