mikebatman

Hello club lexus forums.
I am a new owner of a 1993 ls400.
I love this car. I've had her for approximately 7 months and have had 2 issues hopefully some of you can help shed some light on and advise my best approach.

The first is my mass air flow sensor.
She first began to idle erratically and even stall on me at low rpm a few months of driving.
I used some fuel injector fluid and she was good for a couple months. Acting up again,
I've had the mafs replaced and she is running a lot better. However still fluctuating slightly in park between 600-800 rpm. I paid $300 for this after market part.
I've just found a mafs on ebay for approx $120. The current mafs is still under warranty.
Would any of you advise I buy the mafs for $120, and return the one for $300?
Does model of the mafs make a difference? How difficult is it to calibrate?

The second is my ecu.
At the time of the erratic mafs issue my check engine light and traction off light would come on and off simultaneously at random. Since the mafs was replaced, the lights are now on constantly, and my mechanic says it could be the computer. They say a computer could cost up to $5000.
I've found a rebuilt ecu ecm with a lifetime warranty on ebay for $150. Is this advisable?
How difficult is it to replace the computer myself?
It is my understanding it is behind the glove box?

One more issue relating to these 2 issues regarding gas consumption.
Since these issues have occured, my gas consumption is significantly higher.
Before these issues I was getting 450-550 km (280-340miles) per tank, now I am getting 300-350 km (186-217 miles) per tank.
I live in Toronto, Canada. My ls400 must endure harsh winter conditions.
I'm fairly certain the cold shock is a factor, especially since the vehicle has been accustomed to underground parking until now. And validation of this is greatly appreciated.
As well as any advice and council regarding these issues. Thanks in advance.

By the way my ls400 is currently at 231, 860 km (144, 071 miles)

mikebatman

I look forward to contributing to the forum and sharing my experiences with my new vehicle.
Pictures to follow soon. Body and interior is in great condition.
This is my second vehicle.
My first was a 1996 gmc jimmy sls. Quite an upgrade! LOL

lexxpro

Hello and welcome, I have a 93 ls400 as well. First you will want to diagnose why the cel is on.
This is a great guide to help with that- http://www.lexls.com/tutorials/intro/codereading.html

I would also recommend sending in your ecu to get rebuilt. Mine has about the same amount of mileage as yours and i had to rebuild my ecu with the help of lscowboys thread about 6 months ago. For me it was causing starting issues, flashing check engine light and low mpg.

sam12345

iTrader: (1)

I got an ecu for 80 on eBay as a back up, so far I have not needed to use it. You can also try the club Lexus classified. Get your original ecu and do the solenoid replacement (LScowboy) then put it back in your car. If it works good return your 300 dollar one .

LScowboyLS

yes, it is likely your ECU, and the cause is likely to be sick or leaking ECU capacitors

do not clean a pre-95 MAF sensor with solvents, just gentle compressed air and perhaps a soft chamois

a new computer from the dealshipship could be as much as $2200 or so, but never $5000

junkyard and used ECU's purchased online need to have the correct capacitors installed, regardless of the guarantee, lifetime warranty etc. - I know of no company on earth that is rebuilding Lexus ECU's using the correct premium Japanese low-ESR capacitors, and that is what it takes to make one act right!

LScowboyLS

capacitor replacement

mikebatman

Thank you LScowboy.
This information and the tutorial in your link is incredibly helpful!
I would like to attach the links of the parts I'm looking at on ebay and perhaps you can inform me if the parts are adequate for my needs.

Mafs- http://www.ebay.ca/itm/111038369351?...ht_5875wt_1337

Ecu- http://www.ebay.ca/itm/111038435849?...#ht_1030wt_135

I've contacted the seller to inquire if correct premium Japanese low-ESR capacitors are installed.

LScowboyLS

You can contact the seller and just ask what specific capacitors were replaced (brand & model of each capacitor and how many were replaced, don't even clue him in that they should be low-ESR or what brand, so that you get a truthful answer - if he can't list the brand and model of the new capacitors, then run like hell!

Personally, I prefer to buy an ECU that is a "virgin" from ebay, and then replace the caps properly, rather than some junkyard tech's "hack job"

I have never opened a Lexus ECU that was rebuilt that was done correctly

As far as the MAF, I like original NipponDenso, but yamae would be a better person to ask if the Fuji you found on ebay would work well in your LS400

if you can get an ebay seller to provide you with pics of an ECU opened up, I can tell you whether it is a virgin, or whether it has been rebuilt correctly with the correct parts if the pics are good, but like I said, it would be the first!

mikebatman

The current maf sensor is a fuji and it still fluctuates in park.
Are you saying if I got a maf sensor that you've indicated I would not have these problems?
I am quite capable of taking things apart and putting them back together.
As well as replacing parts.
In the effort of saving money I will be replacing my ecu and maf myself.
The ecu looks like just 3 screws. Is it necessary to calibrate the new one after installing?
And provided the ecu is adequate, how difficult would you say it is to replace myself?

jerryparks

iTrader: (1)

I have a 92LS 400 that is having some of these same problems. Intermitant starved for fuel and surging ) Does the 92 have the same ECU problem?

chicov8

welcome to the club

mikebatman

How long did it take you to rebuild your ecu?
Is the same thread you are talking about the one that lscowboy has linked me to in this thread?

LScowboyLS

all LS400's have the capacitor problem, it is most common on 93-97 but affects all years

you are best to start with an ECU that has never been repaired (a virgin) - post hi resolution pics of the insides of yours here and I can tell you if the caps are original.

please do not deviate from the exact brands and model numbers of capacitors that I linked to in my capacitor replacement guide, or you won't fix the problem, and if you are not good with small meticulous work, you might want to get someone who is an experienced and skilled solderer to do this! - it's not a good "learning to solder well" project