My 94 xjs 4.0 runs better with TCS unplugged?
replaced: coil, thermostat, TCS, fuel filter, no corrosion on any electrical plug.

if the TCS is plug in the engine is sluggish, unplugged engine is very responsive and fast

what is going on?

 

i think the TCS holds the idle solenoid open for cold starting, and should modulate/close the idle solenoid when up to the desired idle setting

if the sensor is wrong it could be closing the solenoid prematurely or all the time ,

does it run well when fully up to temp even with the sensor plugged in

BB

 

Your engine is staying in open loop, so it's not relying on any of your sensors to fuel the cylinders. You are most likely overfueling the car.

I would replace the $20 sensor.

 

CTS Is new...could i have 2 bad sensors?

 

you have three coolant temp sensors, one for the ECU and one for the idiot gauge in the dash and one for the temp warning light, they are not connected

hope this helps

BB

 

The engine, at warm up temperature, still is sluggish with the CTS plug in, Could it be something with the O2 sensor?

 

You have one coolant temperature sensor. The other two sensors monitor engine oil temperature.

Old oxygen sensors could be lazy and provide you with a sluggish responding car. When was the last time they were changed?

 

Good point, that will be next, thanks

 

Second the o2's

though your engine is different the concept is the same, when I did my o2 sensors it was the difference between slug and sport mode. Now the engine sounds better to.

 

Thanks VancouverXJ6, That sounds like positive results to me

 

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