Bypass 2JZ-GTE VVTI speed sensor?

[zolpix]

Hows it going everyone, Im putting a 2JZ-GTE VVTI motor from a JZS161 Aristo in my 1990 GA70 Supra. Ready to drop in once engine mounts arrive from japan. Have been going over the wiring side of things and have a question i'd like some input on. I will be running a W58 gearbox without a speed sensor, My dash gets speed from a cable that goes through a speed sensor behind the dash as it is a digital dash, This sensor is 20 pulses per rev. Can i run the ecu with out the speed signal? I've noticed that idle control is run though a speed sensor, so what will happen without the sensor and could i compensate the signal if needed with my speed sensor behind the dash or will this make idle at too much rpm?. Any help is much appreciated.

Cheers

[wilbo666]

In my first hand experience the factory JZS161 engine ECU will throw an error without the speed sensor.

Personally I tried generating the 3 wire (R154 in my case) speed sensor and this caused a very low speed, speed cut, the only thing I can think of is that this was related to the traction control and lack of these speed inputs...

I'm not sure what you mean by "I've noticed that idle control is run though a speed sensor"... yes the speed sensor plays some part in the idle control, but in general not having a speed sensor will only have very slight effects on the idle. The fact the the engine has a "fly by wire" throttle doesn't really effect how the speed sensor effects the idle.


In other thoughts I suspect you will also have a number of error codes from the missing auto trans and the missing body ECU.... I was always planning to install an aftermarket engine ECU, but regardless I never managed to get the factory JZS161 or JZA80 VVTi auto engine ECU to run the engine to what felt like its true potential...(it felt like limp mode).

Cheers
Wilbo

[zolpix]

Yes after thinking about it, at idle the speed sensor should be sensing no speed at all? correct?. I would like to retain the factory ecu at this point as i plan on keeping the factory turbo's, after all is just a street car. By true potential do you mean factory power output? If i tell the ecu it's in neutral and run the W58 without the speed senor input am i to expect problems? I was aware the ecu will throw codes with the manual trans, as far as i know there was a manual ecu for the jza80 but very rare...just what I've read on the internet though. Do you know why the ecu won't "play nice" in conversions? I remember reading a gs300 article about the ecu being a daisy chain type although i don't fully understand how that works.

Cheers

[wilbo666]

I can only give you my first hand experiance, and that was that it felt like the timing was being retarded and the engine wasn't making the power it should. However I didn't have the factory turbos on, but that was still my feelings.

I do not know why exactly the engine ecu does not easily 'play nice', like I said I spent quite some time faking the auto trans signals, speed signals etc and wasn't able to make the engine ecu happy (in my opinion). You might have more luck

Yes there were manual jza80 vvti, yes the engine ecus are rare

The factory jzs161 engine ecu uses what Toyota call the 'multiplex' network for communications. I.e the engine coolant temperature signal is sent from the engine ecu to the dash, there isn't a seperate coolant sensor for the dash as on earlier engines

Cheers
Wilbo

[dumbass]

daisy chain is canbus system
ive worked on a supra mk4 with 2jvvti and manual box
went good but i had elect spd signal from dash
yr speedo is digital but i think the speedo is stil a cable to orig gbox
u need speedo to work anyway its no use going into this without worryign about getting speedo to work
so yr best of trying to find a way of fitting a speedo drive in box
like is there a different rear housing u can use

[zolpix]

I guess i can just try running the ecu without the speed sensor and see if it all goes well, else i might have to run a speedo signal converter or something. dumbass: my speedo does work, it runs a speedo cable from my gearbox that goes into a speed sensor that converts a digital signal for my dash only.

Cheers

[dumbass]

ok then split that speed signal and run it to ecu aswell
if the motor feels dull
I've also use injector pulse to ive a fake speedo signal
before which does help when u have low rev limits due to
no speed signal

[wilbo666]

Just a note, the jzs161 engine ecu is expecting 12 reluctor (2 wire) pulses per auto trans gearbox output shaft revolution.

I think that your suggestion of trying it without a speed signal hooked up to the jzs161 engine edu and then evaluating from there is a good idea

Cheers
Wilbo

[dumbass]

u loose the auto speed sensor when u go manual which is sp2
but isnt there a wire like the sp1 that comes from dash speedo which also does cruise control and other stuff
so just get a signal into that pin if u have issues
ive seen afew diags with that wire

[wilbo666]

but isnt there a wire like the sp1 that comes from dash speedo which also does cruise control and other stuff

No.

On 2JZ-GTE VVTi from JZS161 my understanding is that the speed signal is sent via the multiplex network (also multiplex is not canbus, they are different ) to the dash. I think there maybe a speed signal to the radio however...

FYI, on 2JZ-GTE VVTi from JZA80 the engine ecu has a speed signal OUTPUT to the dash. The engine ECU takes the 2 wire auto speed sensor (SP2) and uses an output pin on the engine ECU to send an appropriate 'SP1' style signal TO the dash. This is how they got around the VVTi autos only having the SP2 sensor and no SP1.


Cruise control is done inside the engine ECU for JZS161 and JZA80 via the fly by wire throttle (one of the reasons FBW is good for car manufactures as it does idle control, traction control, cruise control, etc without separate discrete components and wiring so I'm pretty sure FBW ends up being a cost saving for the car manufacture).

Cheers
Wilbo

[dumbass]

ok cool
on my info there was a wire that went from ecu to speedo
had funny name rfd or something but it did start with r and was 3 letters
ill get books out later
i wired a 2jvvti jzx161 into jzx80 supra over xmas and this car had a manual gbox
it started straight away and everything worked ok
the book i have doesnt give good info on the speed input or output signal
so not sure how that pins works
maybe ill look up info on what the pin labell means
so if its an output to dash engine still drove ok so it mustnt really need that if u go manual

[dumbass]

just checked my books
pin 25 which on yr diags is called spd and looks liek it does have speed sensor
somewhere and sends signal to dash and ecu at same time

my diags that pin is called rfc

and there is also pin rfc2
not sure where they go as has bad explaination
but voltages on that pin says it changes when a/c is on

[wilbo666]

I'll have to look more closely at it one day

I'm sure of the JZA80 VVTi auto setup tho

Cheers
Wilbo

[George]

zolpix
in case of running manual box you don't ever need to feed speed signal to ecu. Just fool it so it would always think you're in parking or neutral. I can't recall right now 2jzgte's stock pulses per rev, if you still need it I'll find the info for you.

[dumbass]

U don't have to fool ecu
Last one I did I just pulled all auto
wires out and just ran correct start
signal and it ran good