The coolant temp sensor is new and the O2 sensor is faily new...i did the little ALDL thing to see if i was in closed loop...nope..open..now i know where my gas mileage is going..sooooooo why??? lol

I don't have a scan tool or anything...i do have a Stage 2 fastchip but never had a problem with that until now...any advice/opinions would be appreciated

thanks



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did happen to put a low temp thermastat(160*)I've heard that this can be linked to keeping them in open loop.since it keeps it from reaching the correct operating temp for closed loop.

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yeah but with the stage 2 chip they told me to use a 160 thermo...i just got back i AM running a bit too cool..so i'm gonna wire each fan to a switch so i can run a bit warmer

 

use a 180 degree therm, its just right

 

So how exactly have you determined that you are not going into closed loop? Did you take the car for a 10-15 minute drive and then test it?

There are so many situations where you can be going into closed loop but by the time you test it as a "snap shot", you can easily be in open loop.

When you first start the engine, it can take 3-5 minutes on its own. But, prolonged idling or long deceleration down a hill can make you go temporarily into open loop.

The best and most reliable way to confirm your car is going into to close loop is with a scan tool connected and doing 10-15 minutes of real world driving. And not "stop n go" traffic either. The scan tool will confirm if you are going into closed loop, how long it is taking and what criteria is causing it to fall into open loop.

If you remained in open loop for an extended time, you should be getting an SES code.

Also, while there is a minimum temp for ECM to go into closed loop, it is a fairly high number (around 40-45*C or 115-125*F). So if the 160* T-stat is functioning properly, it should not prevent you from going into closed loop.

Lastly, if you have an automatic, there is a separate control for locking the TCC based on temperature too. It is a little higher than the control for Closed Loop. So if you can feel your TCC lock, then you can be assured that the ECM is detecting suffient coolant temp to put you into closed loop.

 

As Glenn said, you need to test the vehicle in real world driving. I had a similar situation. My car would never go into closed loop and would set off the SES light on the highway. When I checked to codes, it was the O2 sensor(forgot which code number). After replacing the sensor and checking the contunuity of the wire, the problem still persisted. It ended up being the computer itself. The computer was not reading the 02 sensor and the break in the circuit was within the ECM.
But before you to buy a new ECM, check everything that could make the system not go into closed loop mode.

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