Stuck in "Open Loop"

[4'running'26]

Hello everyone.

I recently purchased, and am now running, my Scangauge II and it is great! One thing I noticed, however, is that I seem to be in open loop at all times, never reaching closed loop operation.

I recently replaced my O2 sensor after throwing the code P0125. My fuel mileage went up right away by quite a bit (from 17/18 to 20, mixed HWY and City) so I figured the problem was fixed. I am not getting the code on the Scangauge's scanner, but, as I said before, I am staying in open loop.

Maybe the scangauge just is giving me faulty information, but if not, I don't know why I am still stuck in open loop. Maybe the thermostat is stuck? Any ideas?

Thanks.

JT

 

[jgue467]

How many miles have you driven at a sustained 50mph+? Read up in the FSM, it can take 50+ miles at highway speed before the ECU thinks enough distance/speed has elapsed to 'close' the loop.

http://www.toyota-4runner.org/3rd-g...faq-tutorials-documentation-reference-v2.html

 

[4'running'26]

How many miles have you driven at a sustained 50mph+? Read up in the FSM, it can take 50+ miles at highway speed before the ECU thinks enough distance/speed has elapsed to 'close' the loop.

http://www.toyota-4runner.org/3rd-g...faq-tutorials-documentation-reference-v2.html

Interesting. I probably get about 20 miles of interstate per day. I'll be doing about 180 miles, uninterrupted, on the interstate here in a week or so. I'll monitor it then and report back.

Thanks.

 

[4'running'26]

Dang. I spoke too soon. The code did pop up on the scanner. Same code. P0125.

So, if it isn't an O2 sensor issue (unless I messed something up on the install) than is it most likely a thermostat issue?

 

[Smog-guy707]

One very common issue i have personally experienced, is if a vehicle does not reach proper operating temp, it will stay in open loop (thermostat opening too soon) P0125= Insufficient Coolant Temperature For Closed Loop Fuel Control.

9 times out of ten it is a simple thermostat issue, i would start there if i were you. pretty easy to do yourself.

hope that helps

 

[4'running'26]

One very common issue i have personally experienced, is if a vehicle does not reach proper operating temp, it will stay in open loop (thermostat opening too soon) P0125= Insufficient Coolant Temperature For Closed Loop Fuel Control.

9 times out of ten it is a simple thermostat issue, i would start there if i were you. pretty easy to do yourself.

hope that helps

So, do you think the thermostat is sticking? How exactly should I go about checking/fixing the problem? I don't mind getting in there myself, but don't have any experience with the thermostat.

I bought all the OEM parts from AirCabinMan (on EBay) and had the dealer install water pump, timing belt, drive belts, and the thermostat in February. Maybe the issue is stemming from this work somehow?

Thank you very much for the info.

 

[SilverRidgeRunner1]

check the OHMS on your coolant temp sensor, I can't recall if there is a code that trips if the coolant temp completely goes out but if your at one end of the threshold of the coolant temp sensor and it hasn't quite died on u yet(causing a code 125 i think) could be getting ready to... Another thing when u start up in the morning let it warm up to temp do you see if the RPM drop? typically when they do the ECU recognizes that the coolant temp as reached temp.. ECU reads from the info typically between the o2's and the coolant temp...

 

[19963.4lsr5]

My Saturn goes to closed loop as soon as the PCM starts seeing a valid signal from the O2 sensor.

Once in closed loop (usually about 3 min after engine run) it adjusts the Air-Fuel ratio depending on engine temp to complete the warm up.

What brand sensor did you buy. And where did you put it?

 

[4'running'26]

Things seem to warm up quite quickly and the RPMs drop to around 600 at idle.

The O2 sensor is a Denso and I put it upstream. I have a non-Cali spec, so only 1 cat. I bought the sensor off of Amazon.

 

[jgue467]

Have you read thru this and followed the diagnostic procedures within?

http://tacoma.site40.net/4Runner_96...2rmsour/2002/024runne/di/eg5vzfe/cip0125o.pdf

If you want to solve this, follow the FSM procedures - it is what a toyo tech would do and so should you. Luck buddy! :^)

 

[SilverRidgeRunner1]

Have you read thru this and followed the diagnostic procedures within?

http://tacoma.site40.net/4Runner_96...2rmsour/2002/024runne/di/eg5vzfe/cip0125o.pdf

If you want to solve this, follow the FSM procedures - it is what a toyo tech would do and so should you. Luck buddy! :^)

Oh the wonderful pin point test ! Done it a many of times.

 

[4'running'26]

Have you read thru this and followed the diagnostic procedures within?

http://tacoma.site40.net/4Runner_96...2rmsour/2002/024runne/di/eg5vzfe/cip0125o.pdf

If you want to solve this, follow the FSM procedures - it is what a toyo tech would do and so should you. Luck buddy! :^)

Maybe I just don't know enough about it, but I don't know if the Scangauge II has the capabilities to tell me all that it needs to tell me about the conditions when the code was thrown. Am I wrong there?

 

[19963.4lsr5]

My 4runner idling at 185 degrees after a warm 120 degree start stayed in open loop at idle.

I gave it high idle, and within 30 to 60 seconds I started to see the O2 bank 1 sensor 1 start to read something. It went close loop and I let it idle and it stayed closed