coolant temperature sensor

[CMF_murtle]

Just wondering if anyone has tried to bypass it?
Would it work if I put a 300 ohms resistor across the wires, so it fools the ECU into thinking that the engine is always hot.
How bad would the engine run when cold.? I've already done the 15K resistor mod, and found this really successful. Been through the coldest part of the winter without an issue, so thinking that the cold running of the engine can be even leaner than it is now.
Thought I could wire it with a manual switch as well so if needed the sensor could be connected on demand.
WHat do you think?

 

[CMF_frank2]

mine was closed looping and off coldstart enrichment within 1 mile with 2 sensors wired in parallel during sub zero (usually takes 2 miles +).
but the lambda is,nt heated up and functioning till about a mile anyway, so its pointless bypassing the c/t/s really eh

 

[CMF_murtle]

How do you know when it becomes off the coldstart enrichment, and closed looping? I know how to check the fault codes and check the lambda through this.
Can I take it that the engine will be running closed loop once lambda starts to work? Or is there another way to check the change of loop.

Most of my running is short, and many of my runs are about a mile. My spark plugs get quite black during this running, but after going for a longer run they go a normal clean color. I just have a suspicion that I could have the engine running leaner quicker. I currently use 15K resistor parallel.

Could you please explain the process of 2 sensors wired in parallel. I take it that you have the normal one in the engine, and you have another one the same somewhere else. Is this one in the coolant or the open air?
If it is in the open air another resistor of the value of the sensor cold wired parallel would do the same thing would it not?

Thanks for your help

 

[CMF_frank2]

i use a narrowband a/f/r gauge, but a voltmeter on the lambda middle wire would suffice, and the ecu wont closed loop at light throttle until the engine is warm.
the 2nd sensor is under the dash, and is piggybacked/tapped into the 2 wires (colour to colour)
and i guess a suitable resistor would be ok, but it would,nt compensate for ambient temps tho eh

 

[CMF_murtle]

Would the cold start fast idle be worked from the Coolant temperature sensor? Does yours idle cold at ok speeds with the double sensors?

I've been wondering about the lambda voltmeter test. Is this just testing the point that the voltage starts to fluctuate between 0-1 v. Are you saying that once it is fluctuating around 0.5 volts that the ECU is now closed loop? This would be the same as the engine check light starting to flash in the second stage of the fault code mode I guess? If it is it would save me from having to tap in with a voltmeter.

CHeers

 

[CMF_frank2]

the waxstat on the throttlebody mainly governs the coldstart fast idle murtle, and yes the voltage should fluctuate around .5v @ cruise, and 0v @ lift, and .9v @ acceleration or coldstart enrichment.
here,s my gauge during some leanburn testing with lowered fuel pressure
where its off the scale lean while cruising @ 50 mph, then as i slowly increase the throttle it starts to close loop, then goes off the scale rich when i boot it at the end