will my engine cut at 180kmph

[Regan]

im building a 1ggte ae86 and i want to know if i cut the speed line to the ecu will it still cut, what will happen? and if i leave it on how exactly does it pick up how fast im goin, btw i will be runing an a/t ecu on an m/t harness

[Aust162]

from what i've heard, if you cut the wire it will throw a CEL code on your dash. you would be better off fitting a inline switch on the wire so you can flick the when you feel you have to. otherwise your CEL will be flashing at you all the time if you just cut it.

Other option would be to get a hks speed cut device. or full standalone ecu.

[Regan]

an inline switch from the computer to the actual speed system? how does the speed system capture the speed of car

[oldcorollas]

if it's not auto, does it need to know the speed?
for the speedo? (or is it mechanical?)

[Regan]

its an auto ecu on a manual harness on a w58 i want to know if the car is goin to cut 180kmph, i dont know exactly how the speed limiter works on the 1ggte

[SIKTOY]

Regan
The speed cut will not work in you car so don't worry about it

Cheers
Ben

[TA-022]

and it wont throw errors?

cause im the same auto ecu but w58 ...

[CrUZida]

Aust162 is 100% correct.

If the speed input on the ecu is not used, it will throw a code (code 42, assuming you hook up a CEL) as soon as you reach about 3000rpm for 15 seconds or greater (I think those are the conditions?), but you will not speed cut.

If you connect the speed input then it will not throw a code, but the ecu will cut every 2nd fuel pulse when the speedo reaches 180kph.

[JP]

you can install a jaycar digital speedo corrector kit inline with the speed sense wire to the ECU, adjust it down and raise the speed limit.

It's a 4 pulse per revolution signal from the dash cluster to the ECU originally, with the jaycar kit you can halve it if you like.

[CrUZida]

Depends on the ecu JP.

Newer ones are like that (I know JZX100 is), but earlier ones are the opposite way.

The signal goes from the gbox to the dash, then the dash to the ecu.
So you'd need to intercept the wire going from the gbox to the dash.

This is assuming its electronically driven.

[JustCallMeOrlando]

The only other thing the ECU uses the speed sensor wire for was for knowing when you're coming to a stop/idle. That said, mine was never connected for about the year I had a factory ECU, both the Gen2 and Gen3 I had on there.

[Mos]

The AE86 has a glass reed switch inside the speedo assembly, activated by (IIRC) four magnets in the magnetic coupling. From memory one side is grounded and the other goes to the SPD (or SP1 or SP) input of the ECU (which usually has an internal pullup resistor).

As far as I understand, most mechanically driven speedos in toyotas have this switch. Some have an electronic speed sensor inline with the speedo cable.
Aftermarket speed sensors are available that will fit inline with the speedo cable, with various pulse per rev configurations.

Mos.

[JP]

the speed sense signal in my GX81 GT with manual 1GGTE went from the dash to the ECU. The Speed signal output on the back of the actual speedo assembly was screenprinted with "4P"

So if Regan wants no speed sense CEL's, he can wire the output from the AE86 dash (all AE86 speedo's have the reed switch output that MOS described) to the 1G ECU, and put the jaycar kit inline in that wire to modify the speed cut.

[Regan]

k wtf is a jayline inline kit im in peru hehe anyway i can do something here or fabricate it i dont know

[Regan]

i was checking out the diagram and thier is this box that says speed inficator speed limiter turbo indicator exhaust gas temp and chech engine, i can tell this goes to the cluster which i dont have but other then that is thier a seperate box where these things go because if thier is i dont have it either, other then the cel blinking will anything else happen, in the 20 valve 4age the rev limit would go down a couple 100 rpms