Originally Posted by zukikat

Hi Tach,
I've got what I think is a failing ECU on a 94 LS400 I bought last week from a car lot.
I test drove it 2 days in a row and the CEL came on during decel or stopped condition but went back off within moments after accelerating again every time so I checked for codes and it reported only an AFM code, which I have a spare of from my 1992 Turbo Supra and decided that was a non-issue since the car seemed totally drivable anyway, so aside from being at a major service interval (timing belt/water pump needed since there's 184k miles on the car and a totally unknown service history) and there was also some overall general maintenance needed and really horribly warped rotors, but the car seemed to idle normal and run smooth and drive properly so I bought it on day 3 and handed it off to a buddy for a timing belt/water pump and overall check-out and some other basic tlc because I'm a long-time 5M/7M/2JZ Supra fan whose never tried a timing belt job on a V motor. before and didn't have time to figure it out.

The LS made the 2.5 hour trip to my buddy's place for servicing and made it back home again a few days later with no real issues to speak of but now occasionally it acts like I've begun switching the key off/on/off/on/off/on rapidly, tach actually falls to zero and it's NOT a problem with the tach it's actually like the engine has been shut down and recovers just as quickly. The CEL comes on when the tach falls and goes back out when the car jumps back to life and back and forth in less than 1/2 second intervals, it's that fast, and eventually it will either jump back to normal or flat out stall if I'm at low speeds and trying to turn, and when I put the jumper it for checking diagnostic codes it just flashes "all good", no codes at all.

That's one of the two nasty gremlins.

The other really nasty gremlin is that it will stumble momentarily, lose all power, go absurdly rich (exhaust makes your eyes water!), light the CEL, pretty much stop managing the tranny at all, and put the car in "limp it home" mode, making it fling gravel and "burn out" in reverse but a bicycle can accelerate faster in Drive and it's undrivable and completely unsafe in that condition...
Oh, and it will NOT acknowledge insertion of the TE1 to E1 jumper into the diagnostic block at all for 10-20 minutes, when it finally does think about recognizing the inserted jumper it randomly decides to flash "all good" or go back to ignoring the jumper, and another 10-15 minutes later it'll mostly just flash "all good" with the occasional stumble of the flashes (both the CEL and O/D Off light stumble together when that happens) PLUS the ECU will NOT reset at all that whole time.

So at this point I've concluded that either I have a major electrical problem (harness/wiring fault) or the ECU is in the process of failing, which explains why the lady got rid of this otherwise really nice overall car that's really clean inside and out with clean/clear carfax and auto-check after the 12 years she had it as owner #2 and why it passed through 5 used car lots in one month, so I discovered when the lot I got it from handed me the title...

Although it did have power steering leaks I'm giving the alternator the benefit of the doubt because the battery warning light is good but not showing any problems and everything electric seems to work as it should including headlights, security, etc, and even with the factory security system armed the battery holds a charge for days and days without the car being driven so it's apparently charging normally as far as I know...

NOTE: When I got the car back home from the timing belt (and other) servicing by my buddy I did replace the AFM sensor module (bolts/screws to the AFM housing) with another identical one (same P/N) off a 7M-GTE powered Supra and reset the ECU and drove about 25 miles of mixed interstate and city stop-n-go and the CEL on decel and Code 31 seem to have been resolved but it was on that test drive as I was satisfied that the problem was fixed and got off the interstate that the on/off/on/off/on issue first appeared for me and the next day was when the car went into "limp it home" mode.

We were originally hoping that the random drivability issues with stumbling/stalling and hesitation and running really rich when the CEL was on were possibly the result of the AFM code that kept appearing on decel as that's about what a 7M-GTE Supra does when the Karman Vortex AFM sensor gets screwed up or goes bad, but the AFM code issue being seemingly resolved after the AFM sensor swap and all the other symptoms still remaining PLUS the ECU not responding to the diag jumper for long periods after it goes into "limp it home" mode makes me believe the ECU is dying.

So my two questions are....

1. Does my conclusion seem feasible and reasonable based on symptoms?
2. Does anyone on this forums repair failed ECU's and/or send advance swap-outs with like a core charge so I can get back to driving this car ASAP?

I bought this LS400 because the car I'm commuting in now is borrowed and the owner wants his car back ASAP so I need this LS400 to be stable and highway worthy asap.
It's totally "serviced" and good to go, but it's not usable with those two problems because I can't afford to be stranded on the interstate along my 50 mile commute in the middle of the night or have it decide not to be drivable when I get an emergency call from work.

Thanks in advance for any help you can provide!

Originally Posted by 2jzosht

Hi Tach,

I have 92 sc300 5spd and over the last month the radiator fan runs constantly while the car is on, it sounds like I am driving a bus. I'm not running hot, where and what should I check first?
Thanks

Originally Posted by Bocatrip

Hi Tach, My 2001 LS430 with 103,000 miles seems to have a very slight coolant leak which more than likely is coming from the coolant expansion tank. I've noticed that the tank is integrated into the fan shroud assembly as one entire unit. The cost is fairly reasonable at around $125-$150 for the tank. What would you estimate is the amount of labor to replace one? Have you heard of these tanks going on the LS430? Thanks very much for your help.

Originally Posted by entryspeed

Mr Tach, I want to thank you for your time in advance. So here it is I just did the timing belt, tensioner, idlers, crank seal, cam seals, water pump, and valve cover seals on my 99-gs400. I cleaned every thing put it back together and it ran perfect BUT. the left f-ing OCV-vvti actuator is clacking on the left side. SO knowing the filter was under the front cam cap. I took 80% of the **** back apart to pull the cap off and clean the oil passages and filter etc. I also took out the OCV itself and took the piston out and cleaned it and tested the selinoid with 12v to see it activate. I put everything back together again she fires right up but still CLACKING like a diesel on that side. It is definetly the ocv valve as I scoped the noise etc. The engine runs smooth and I broke in the timing belt with 20 easy miles then I let her rip and it has a crap load of power but still clacking like there is no oil. I did do an oil test while it was apart I disabled the ignition and turned motor over. The oilpassages filled up with in 5 sec and where pumping oil out in a good manner. The ocv valve never made this noise prior so why now after I did all this work. Do I need a new one? Thanks again

Originally Posted by msdelexus

Hi Tach,

I do hear a squeak coming from my steering wheel. The noise is intermittent and somewhat faint but noticeable. Is there a special lubricant to fix this and which specific part of the steering wheel should it be applied to?
Thanks.

Originally Posted by bmwboyee

Tach,
Thanks for everything you do for the lexus community.

I have a 1999 RX 300 with a P0171 code that is thrown. I have cleaned the MAF and air filter. I have not replaced the MAF or any thing else. Was thinking of replacing the O2. Would any O2 sensors from Advance Auto parts work? the reason I ask is they have some really good coupon codes, up to 40% off and would love to take advantage of that.

Not sure if this link will work:
http://shop.advanceautoparts.com/web...p2HomeClicked=

Thanks again.

Originally Posted by al-ex-us

Hello Tach Motor - I have a couple questions about my 98GS4.

About 100 miles ago, I got an error code indicating the throttle control motor w/magnetic clutch isn't working properly (error code - 1126). My mechanic tells me it's about 370.00 dollars for the part alone, but it could be resolved with a simple cleaning of the throttle body, throttle body sensor, or M. A. F. sensor with the right cleaner(s). Since I am not that mechanically inclined, I could use some clear instruction on how to do so without messing anything up. If possible, submit a diagram or picture so that I can "see" what you are explaining.

Thanks in advance~

Originally Posted by TACH_MOTOR

You can get some grease, Toyota/Lexus sells the steering shaft grease its a yellowish color. You put it on the steering shaft down low.

Originally Posted by msdelexus

Hi Tach,

When you say apply the steering shaft grease on the steering shaft down low, do you mean way down outside the under carriage of the car where the main shaft meets the other steering components or it just the steering column from the inside of the car? Pardon my ignorance as to where it is specifically located. Hoping you can guide me to it.
Again, thanks for all the helpful advises you have provided us members on this wonderful forum.