1uz wiring question

[motoracer47]

this is from Phil Bradshaws 1uz Q&A:

The 90-92 LS400/SC400 ECUs seem to be a problem child for some reason – these have 4 x two-row grey plugs and I have had about a 30% success rate with them so far. They all start and idle ok, but for some reason many won’t rev beyond about 2800 RPM. I do not know hwy this is – it makes no difference whether the loom was cut or intact, whether the auto trans is there or not. I wonder if the missing traction control is part of the problem, but it doesn’t affect any other ECU.

Noting that this style of ECU was only used for ~2 years, I wonder if it is a design fault where they are prone to failure. Diagnostics has not been of any help either. Ironically reconfiguring the ECU pins to suit a Crown computer has resulted in a 100% success rate, without changing anything else.

Note that ordinarily redline is around 6500 RPM with the rev limiter cutting in at around 675......................

Is this still considered good info? I purchased a 94 LS400 engine mainly because of this. However, Ive noticed that the vast majority of wiring schematics and diagrams are for the 90-92 ecus? So you CAN get these ecu's to work?(90-92)
In the Specs and info section (http://www.lextreme.com/misc.htm)
it shows ecu diagrams for 92-95 sc400, but according to the above mentioned article, 92 should not be the same as 93-94!? (and atleast in the states, it would appear that 95 was the switch to obd2, so I would think that ecu is vastly different? Is this an issue of: this info is only for non-usa vehicles?

I really really hope this doesnt come off as a jackass...but the more I research, the more conflicting information I find out..needless to say, it just keeps getting more confusing.

To sum up:
I bought a 94 LS400 1UZFE with fully intact wiring harness because above article said that 90-92 does not work. I cannot find any wiring diagrams or schematics on here for the 94 OBD1 LS400 ecu, but plenty for the 90-92 ecu's that "dont work"

Does anyone have usa based 94 LS400 diagrams/schematics? Has anyone wired up a 94 usa based? Is the usa 94 ls400 wiring the same as non-usa?
Did everyone else switch to obd2 in 95, or just usa? Is the sky blue? (just checking you are paying attention


thanks for any help

 

[cribbj]

Brad, since you're swapping this into a BMW, do you really need/want an OEM ECU? Wouldn't you rather have a more contemporary unit that can give you true sequential injection, and either waste spark or sequential ignition that is crank triggered? Or are you pretty content to stay with a stock motor and keep it NA?

In the US, you would be well advised to contact Doc Tweak of Phoenix Tuning to give you a hand with the wiring. That or hookup with Sideshow over in Oz, as he's probably forgotten more than most of us will ever know about getting swaps wired up to run with OEM ECU's and other variations.

 

[motoracer47]

gonna respond on PM

 

[sideshow]

ive never had a 1uz that i could not fix with a 2000 to 3000 rev problem in over 80 1uzs

if its wired correct then that wont cause it
the problem witht he 4 row ecus is that there is very minor differences between models
and without proper diagrams in the past ive had to power everythig up and hook up a scanner and read live data as i test each of the left over pins

to have about 30% of these ecus causing this problem definately points to a wiring problem as you would not get that many with faulty ecus or sensors

another thing is u cannot beat a factory ecu if you plan to keep it plain and simple
going aftermarket depending what ecu u get u will definately have minor cold stasrt problems and transmission issues if u keep it auto

 

[sideshow]

another thing i tell everyone to do is
if u bought a bitsa engine and wiring and ecu sell it and buy a complete set

these ecus all have a main plug or 2 or 3
then the last plug of 2 which goes up to the dash
now when i wire up these 1uzs its best to have the correct dash plugs on the ecu as this will give u a bum steer

PAY THE EXTRA MONEY AND BUY THE KIT FROM SOMEONE WHO KNOWS THEIR STUFF
DONT BUY IT IN BITS JUST TO SAVE AFEW BUCKS
DONT BE BLOODY TIGHT ASSSSSSS

way too many times being tight normally turns out to be expensive
trust me i know and i do charge extra especially if the customer has supplied me a box full of chocolate assortments heheheheh

 

[motoracer47]

slideshow,

Yea, if it would have been an option for me, I would have bought a complete setup, but unfortunately everything local I could find was already pulled engines without ecus, I just went for the one that had the compete wiring harness. My harness is not cut anywhere, so I would assume I have all the plugs.(?) Ive since found some more info, and I think I will be able to figure it out, just going to have to get the ls400 wiring supplement for 94 usa cars.

lol...I do tend to be a tightass, just ask my girl!

 

[motoracer47]

Anodyne,

thanks, im sure those will come in handy!..

let me ask this...as the sensors are all the same for the obd1 engines...lets say I'm going to build a custom harness, and could pick any obd1 ecu, but it had to be USA based, which would be the best to go with? This limits me to 89-94 ls400 and sc400.

 

[misaelmelchor]

so is the wiring ecu diagram/harness different from 90-94 and 95 and up? i have 95LS400 im swapping in my s13...

 

[motoracer47]

finally back...

Im not completely sure, but I would assume they are quite different. From my research, here in the US, 95 was the year Toyota switched the 1UZ to ODB2, so im thinking that they are quite different. (94 and earlier that is)

 

[sideshow]

94 95 is the change over period for most 1uzs
Sc400 and ucf10 goes to ucf21
If the ecu plugs are similar then changes won't be to great
I'm not sure what u mean by obd2 or if u know what it means
But I have not seen any 1uz looms with an obd2 diagnostic
Plug until after 97 98 models
And before that Toyota don't call it obd1 like they do in the USA
Anyway as u can see there is about 6 or 8 different looms from the
90 s some are similar with minor changes
Some change drastically once they design a new ecu
Finding what the fiddly wires do that makes the job work perfect is
The hard thing and sometimes I plug a diagnostic scanner to the ecu
So I can see what these extra wires do

 

[motoracer47]

sideshow.....sorry, should have clarified, Im in the USA, so I was referring to USA cars. Again while im not entirely sure of the year, it had to be by 1996 at the latest, as any new car sold in USA starting in 96 had to be OBD2 compliant per federal regulations.

Unless we are talking about something else called OBD...On Board Diagnostics...all USA cars from 1996 onward had to support this communication protocol, and all USA cars 96 onwards have the same diagnostic port, and all cars must have the port under the drivers side dash, able to be accessed pretty easily.

Im guessing that OBD protocols may be different for other countries, if they use it at all. Im also assuming the plugs could be different as well. I can grab a pic of this plug if you would like. I have no idea if the factory diagnostic tools use this plug, or some plug in the engine bay. All OBD2 compliant readers only use this plug.

 

[sideshow]

Ok cool
Yea USA diags have obd2 from 05 or 06
I have all USA based diagrams and they are slightly diff to my jap ones

 

[motoracer47]

no worries, and again, my bad, should have mentioned I was talking about US spec.

got a question that im going to send you a pm about.