No speed sensor signal= ?

[JORAMI17]

The car:

1991 Supra Originally 7MGTE Automatic
Now 2JZGTE Aristo with a R154
Single T67
Factory ECU
Factory Injectors
USDM Cams
Factory 7MGTE Fuel Pump

If there is no speed sensor signal from the cluster speed sensor to the ECU what or how would the car behave?

 

[hvyman]

Are you getting a code? If the speed sensor is not hooked up to the Ecu you should be fine. It's used for speed cut.

 

[JORAMI17]

Are you getting a code? If the speed sensor is not hooked up to the Ecu you should be fine. It's used for speed cut.

I am getting code 42.

 

[JORAMI17]

Anybody else? Any other possible symptoms?

 

[ifyouaint1sturlast]

Car should behave fine unless you were automatic, my speed cable failed when I was R154 and it made no difference.

 

[Poodles]

Auto isn't going to shift right.

 

[JORAMI17]

This is a R154 car. This thing does not want to rev at 100% throttle but if I back off then it goes.

 

[hvyman]

If the speedo works I wouldn't worry about it.

 

[JORAMI17]

If the speedo works I wouldn't worry about it.

Ok...so my speedo didn't work before and so I replaced my speedo cable last night and it definetely feels a lot better. It still feels like it pulls back during WOT but not as bad as it was. I think now is leaning out and pulling timing, the sound of the car under WOT is completely different now and now I'm hitting fuel cut almost on every pull. BTW, I did hit speed cut this morning on my way to work and almost crapped my pants, not used to that.

 

[JORAMI17]

Ok...so my speedo didn't work before and so I replaced my speedo cable last night and it definetely feels a lot better. It still feels like it pulls back during WOT but not as bad as it was. I think now is leaning out and pulling timing, the sound of the car under WOT is completely different now and now I'm hitting fuel cut almost on every pull. BTW, I did hit speed cut this morning on my way to work and almost crapped my pants, not used to that.

I think this whole statement is BS! I'm calling myself out!

I finally figured it out and it was the silliest crap, I had heard about the "12v mod" but never looked into it. I guess whatever makes the fuel pump switch from low voltage to high is not present so I jumped the fuel pump resistor box to get constant high voltage to the pump. The difference is incredible, it's like I'm driving different car.

 

[3p141592654]

Speed signal is used for many ECU calculations, including idle, trailing throttle fuel cut, and mixture control. You may not notice any gross effects of no speed signal, but there are plenty of subtle ones.

 

[A70BoosTFienD]

^just about to say that^ when i had my speedo cable break the car idled real low and shitty like 450 400 rpm but i got to 152mph lol. you might want to check your tps just to make sure cause that made a ridiculous difference in my car. ive been running 12 volt for a while so i cant imagine how terrible wot was lol