Can no speedo input = running rich?

[Twisted XJ]

I have 94 XJ and since the Tcase was reworked and the speedo cable not hooked back up I have had a loss of power and running rich to the point of my flowmaster catching the carpet on fire. It is running really rough and I can't pinpoint the cause.

 

[dmillion]

Yes, absolutely. The entire engine is computer controlled, and one of the most important inputs used by the computer is vehicle speed. Guess where it gets that from?

 

[XJJack]

Yes, I didn't think it was going to be as bad as it was, but I guess the computer realy has a hard time with out that input. Mine was not working for abaout 4 months and over time it seemed like I had less and less power, so it must be a learned thing. But it was running rich and ovcourse the shift points were all way low, it would up shift at about 3300 instead of being able to run it up to 4800 at WOT. Now it is hooked back up, and after about 100 miles it is picking back up the power.

 

[tealcherokee]

No.... the speedo gear on the tcase will not in any way effect fuel delivery.

The throttle position sensor, intake air temp, coolant temp sensor (on the tstat housing), manifold absolute pressure, and oxygen sensor will...

NOT the speedo gear assembly

 

[XJJack]

I don't know if is suposed to work that way, just posting real history for me.

 

[Blue XJ]

My speedo cable goes right from the tcase to the speedometer, no computer connection anywhere.

 

[lawsoncl]

My speedo cable goes right from the tcase to the speedometer, no computer connection anywhere.

Do you have a Renix (pre-91) XJ?

No.... the speedo gear on the tcase will not in any way effect fuel delivery.

The ECM does use the VSS sensor and throttle position to determine if the vehicle is decelerating. While in deceleration mode, it will use the idle air control motor maintain a set engine vacumn. (Per 1995 FSM, page 14-25). In deceleration mode, the ECM will reduce the injector pulse-width and delivery less fuel (1993-1995 Fuel Injection Manual, page 3).