ecu part numbers and compatibility?

[the toecutter]

i get no check engine signal from my ecu. i'm looking to price out another (in case it's the ecu at fault), but the previous owner has gone and torn the part number sticker off. marvelous. there seems to be a few variants for my unit. as far as i know, the engine/ecu is from a 1994 us spec (non california model) SC400. which numbers will fit the bill?

http://www.toyodiy.com/parts/p_U_1994_LEXUS_SC300~400_UZZ30L-ACPZKA_8404.2.html

 

[gloverman]

The first one and second one interchange as the second one is a superceded unit. I suspect the Cal spec unit will have air injection outputs so maybe avoid that one. Not sure on the last unit. Over here I interchange any 40/40/40 ECU in manual conversions. We see soarer and crown versions and the main engine inputs and outputs are the same. A/c output is different and a Crown unit will throw a ECT code when fitted to a soarer. I generally get the original unit rebuilt as a first option. Cheers

 

[the toecutter]

thanks, that narrows it down a fair bit. a/c is a non-issue, since i have none. and as far as i know, the only models available here with the 1UZ engine in '94 were the SC and LS 400, and the ecu for these are quite different. the plugs don't even match, so are not easily interchangeable.

much as i would like to have this current unit refurbished, it looks like someone has already done so. in addition to the part # stickers being removed, there are "warranty void if opened" seals around the perimeter.

i would like to keep the downtime to a minimum, so i would probably opt to send a used unit to be refurbished since the current one runs fine (just no cel). but on the other hand, a used unit runs ~$200 + refurbish/reprogram ~$300 = $500. compare that to a stand-alone megasquirt unit for ~$600 (the us$ is pretty strong against the nz dollarydoo, or whatever the unit of currency is called down there), perhaps it's worth the extra $100.

http://www.trademe.co.nz/motors/car...ormance/electronics/auction-462884792.htm#qna

 

[gloverman]

OK. but remember you get what you pay for. Im not willing to say any more about that supplier and the product. Cheers

 

[the toecutter]

that doesn't exactly sound like a ringing endorsement...

 

[the toecutter]

sent the vendor for megasquirt some questions about a week ago, haven't heard back. doesn't inspire a lot of confidence...

be that as it may, i managed to get an ecu #89661-2440 for $100. plugged it in and it seems to work, but at first the engine wanted to idle very low to the point of stalling and being hard to start cold with no throttle. seems to run fine at running temp, test drove through all gears. there is something that looks like a vacuum switch on the top side of the engine that is buzzing, which i don't recall buzzing with the old ecu.

from what little i can find, the main difference between this unit and the 89661-2430(1) is that it is wired a bit different some slight sender/engine improvements and preparing for obdii. it will run a 1994 engine ok, but the cel will not go out. but i still don't get a cel signal from this other ecu (plug A, pin 6, blue with yellow stripe wire).

if it will run ok on this ecu, ill send the one it came with to jet performance for a refurbish. now that i can get a closer look at this unit, it's looking like it is, in fact, a #89661-24230(1). it looks like they changed the colour of the print on the label, and had a second label with a large "30" on it.

 

[George_R]

the buzzing valve must be charcoal canister purge one. try to pull the codes. it's very likely that there's some trouble with sub o2 sensors

 

[the toecutter]

that's my problem. i have no cel signal, ergo no codes. i switched the ecu back to the original, no more buzzing vsv. it looks like that vsv has something to do with the fuel system. be that as it may, i have a used 89661-24230 ecu on its way to have rebuilt/reprogrammed. it seems that the main difference between the '92-'94 (24230) ecu and the '94-'95 (24410) ecu is that the latter does not have a cold-start injector and somehow steps up the fuel system for cold starts instead.

it seems that 1992 through mid-1994 ecus are interchangeable, but the mid-1994 to 1995 is unique to that period and does not flawlessly interchange with any other year.

it's too bad toyota/lexus have become such pricks about having any parts diagrams or technical specifications up on the web anywhere.