Hello everyone.

Been testing open loop cruise AFR's and gas mileage. Had 2500~3500 set to open loop. Car seems to run good, but now I need to check what closed loop trims look like.

2 weeks ago, I pulled my Trim Fuse to reset Trims and wasn't thinking, but left my car ignition state on to accessory when I pulled it. It was in the same state when I plugged it back in. Since then, I have no Trims.

I do get 02 Feedback, O2 sensor voltage, but no trims.

One day while logging, with what should be trims activated, my EVOScan completely glitched, and everything logging enabled or not, updated with data that was incorrect. Then on another day, I was cruising and not logging, and when I plugged in my laptop to take a look, I had a Mid Trim, but would not change. Now it is gone again.

I have tried the whole range of tricks that other posts have yielded with no luck.

I have played with the Rear O2 Tephra patch, enable and disabled. Played with resetting and activating the TRIM feature in the periphery bits as well. I have even enabled my Rear 02 bypassing the Tephra 02 Patch. All the time, I get 02 Feedback, and 02 voltage on the front sensor. However, with the patch disabled and actually logging on my rear 02, I get no voltage on logs for rear 02. It was there for a moment, and then disappeared.

I am not sure what to make of any of it.

My 02 Feedback either way says my trims should be close to +/-2.0%. I would love to see, so I can do a little MAF scaling as well with the MAF Adder for areas in cruise.

Can anyone give me an Idea of what circuit the Trims are on, and maybe a fuse besides the engine compartment fuse panel with 20 amp in location 3, that we all know resets learned data?

Edit: Well, I thought I had figured it out. I left the fuse out for about 2 hours, and then plugged it in. Loaded a completely stock map, and started it, to my surprise car idled and ran somewhat ok. Then I reloaded my latest map, with Tephra 02 patch disabled and running on the Rear 02. Started up, and guess what, I got Idle trim to show up. It looked good. Let car warm up and watched it log and change. I also had Rear 02 signal. Took it for a drive, unfortunately no Mid Trim after 30 minutes of driving on the freeway. MAF HZ was fine and below the Mid-High transition HZ. So it should have logged. Pulled over, Idled for 10 minutes, no change in Low Idle Trim. So I loaded completely stock rom again, started, idled for 2 minutes, then reloaded the last known good rom that gave me trims, with Rear 02 Disabled this time, and Tephra Patch on Front 02 Active. No Trims what so ever. Idled for 10, nothing, drove for 20, nothing. In all cases, I had STFT 02 Feedback, Front 02 Voltage, and Rear 02 Voltage. Just no updated trims. Scratching my head now as to why it works for a few seconds then nothing. Random showing in logs, then back to nothing.

Anyone got any ideas?

Edit:
Just found this in another post... https://www.evolutionm.net/forums/ec...l#post10831962
Can anyone comment on this, if it is true or not? If so, I need to update my tuning for Lower Thermostats Thread, This is definitely a need to know answer.

Currently this makes sense. In logs the times I see the Low or Idle trims is in my garage, where ambient temp hits 21 C / 70 F + degrees, Intake temps see 50 C / 120 F, and Water temps sees 81 C / 179 F. But the minute I hit the Highway, or drive outside, ambient air temp is 1.5 C / 35 F, Intake temps while driving average 7 C / 45 F, and water temp is about 75 C / 169 F. This puts it well below the above suggested water temp to trigger trims. ALso makes sense why I see 02 Feedback and 02 Voltage. SO the system is theoretically working, just being disabled by the water temp switch.

Does anyone know which switch the Trims vs. Temps switch is located in the ROMS. This is a must for running a colder Thermostat and tuning for it.

Thanks in advance,

 

Does anyone know of a way to test the ECU circuit like the fuel circuit to see if it is dorked in the ECM?

 

Bump for update in post 1.

 

Double bump. New information and Data learned. Post 1 edited again. Need some help from tuners, Tephra, Merlin, or any disassembly person on this board, would be greatly appreciated.

 

BUMP. WIll Pay for more disassembly on the ROMS, need this temp switch listed in post 1.

 

What temp thermostat are you using to get 75C coolant temps during cruise?

If your CT sensor is reading a tad cold that won't be helping your cause.

It would also be useful to know, as far as searching for what temp thresholds enable/disable the LTFT calculations, whether you can detect whether the trims stop being updated once they start being updated (having gotten to at least 80-81C) and if so what coolant temp that might have happened at.

 

I am using the 76 Degrees C THermostat.

I know you can calibrate within the ROM I am using, just not sure what would be the correct procedure. Prior to the change of Thermostat, it seemed to be acurate, so not sure if calibration is needed just from switching.

Logs just show them start to read at those temps. They changed as well in logs as it idled above those temps. Stops updating once it falls below.

 

There is a min Coolant temp for closed loop setting. Try checking this thread for your ROM https://www.evolutionm.net/forums/ec...p-address.html


EDIT: sorry just noticed you are already aware of and tried this in your other thread. Good luck figuring it out.

 

And it didn't strike you as surprising that you were logging CTs less than the nominal opening temp of your thermostat when the engine should be at operating temp?

If the CT sensor is halfway accurate, I would expect you should be logging CTs at least a couple of degrees over the nominal thermostat opening temp... that has been my experience anyway.

 

In my garage, temps reach 78 C/ 174 F, outside when I have been testing, it has been at 0 C outside, so the car idles at 168 F / 75 C. So in a garage it sees CT where it should be.

Have you had a look at this thread, to see what I have changed? https://www.evolutionm.net/forums/ec...hermostat.html

I have changed all Temp scaling to accommodate the new Thermostat. Supposedly there is a switch in the sub routine of the Trims that will only activate the trims when above 80C. Also, see the bottom of post one for more info on the switch.

Logs show this to be happening. Like I said above, in my garage, where temps aren't freezing, Temp does get hot enough to trigger Idle Trim for a brief time.

 

Well if all else fails, you can always go the hardware route and trick the ecu by messing with the resistance of the actual temp sensor so that the ECU thinks its getting that hot. If you need to raise the resistance you can add a resistor in series, and if you need to lower it, you can add one in parallel.

Edit, looks like typically you want to raise the resistance to simulate hotter temperature, which is good because thats easier then lowering it. Just add a couple ohm resistor in series (in line) with the temp sensor and it will fake a little bit hotter temperature. You will have to do some maths to figure out exactly what ohm resistor to use though to get your desired target temp.

 

I think calibration will do the same thing. Not sure though. I'd rather find the switch. I have offered money to any disassembler to find it, it lies in the Fuel Trims subroutines.

 

Yah if you have the ability to adjust the calibration that would do the same thing. I haven't seen those tables either though, not that i have ever looked for them.

 

I have the calibration tables for the sensor.

What I don't have is the Water Temp Fuel Trims activation switch.

 

Well don't let perfect be the enemy of good. Recalibrating the sensor seems like a good solution at least until you can get the perfect one.