Open or Closed Loop Mode?

Kyle F

Addicted to Boost
What would cause the computer to switch from Closed to Open Loop once it has warmed up, the O2 sensor is working and coolant temp is at about 170-180?

I am trying to chase down a knock problem(you can refer to my other post for all the crazy trouble codes and what not...


I have eliminated the ground probelm as I have cleaned and checked everyone.
If you have the Thrasher chip in there, it's more than likely normal. If I remember correctly, the Thrasher goes into closed loop at idle and cruise, then goes open loop when you goose the throttle.

IOts completely random. sometimes it fall into open when you are setting at a light and when you are on the road, didn't really look at WOT, but it struck me as odd that it was doing it while setting at a stop light.
Have you checked the connections of the 2 wire harnesses going into the ECM yet? No corrosion or broken pins?

I believe that the Thrasher is always open loop at idle. Should be closed loop driving and not under heavy throttle.

Thrasher really likes tps and iac adjusted correctly.

If you are still seeing a variety of odd values and malf codes then I would still suspect one or more bad connections. Could be chafed wires or bad power. A spare ECM is good to have, but would take a few days to get. You might try having your alternator checked, but I don't know if they can test for high levels of noise.

You can run T-link with key on and engine off and monitor tps while pressing the accelerator. Look for dead spots or big jumps. You could probably try wiggling wires to check for loose connections and see if Tlink starts recording wierd TPS, IAC, MAT, MAF or other values.

Originally posted by RareT
Have you checked the connections of the 2 wire harnesses going into the ECM yet? No corrosion or broken pins?


Yup, pulled out the ECM and cleaned the contacts with rubbing alcohol. Checked all the pins, one was a little out of line, strightened it out and everything plugged back in fine. No other corrosion anywhere... only 45,000 miles on the clock.

Oh and idle is great. TPS Voltages check out and so does IAC counts. I would liek to see them a little lower, but I wont complain because they are within spec.

What I cant figure is why all this crap is happening... I think that onl the computer will be left soon.

Anythign else?
Yea, I feel I have pretty much Eliminated the chip being the problem.

Any Ideas on the Error codes and why I am getting so much KNock?
I'll take a look at your T-link files if you want to email them to me.

Are you just down to having knock, or are you still throwing boocoo codes after checking wires,etc?

Still having the Codes as far as I know.

I would be happy to email them to you, but the laptop has no internet access, and I am not 100% sure how to get them off of there. Never even thought about it. Heck come to think of it, I dont even know how to delete them.

I would be happy to pay you a visit if you would like and don't mind and let you look at the car and the laptop.

My brother seems to think that a ignigtion wire was the culprit, but well you would have to see it to understand.

Anyone know where to get a nice custom set of wires for the TTA?