Long term fuel trim reset

[kcabpilot]

The other day I got a SES light with codes P0174 and P0150. Using Torque I could see that both short and long term fuel trims for bank 2 were way out of whack. I found the connector for the forward RH side O2 sensor oil soaked, cleaned it and now the short term trim reads normal but long term is still high. Is there a way to reset it or do I even need to worry about that?

 

[discostew]

It should slowly come back.

 

[ERover82]

Mine never reset even after many months.

See here: https://discoweb.org/forums/showthread.php?t=92885

 

[kcabpilot]

I suppose there is ultimately a way to reset it but I guess my question is "do I need to?" I'm not really sure I understand what "adaptive values" are to be honest. Are they simply records to be viewed by a person doing diagnostics? Meaning they don't have any effect over what the ECU does to run the engine.

 

[number9]

I'm not really sure I understand what "adaptive values" are to be honest.

Would suggest you spend some time to read and digest the information available in the Workshop Manual. Engine Mgt. section gives a fairly straight forward explanation and some procedures for those having a bit of of technical sense.
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[leftlanetruckin]

You need to reset them using some Rover specific kit.
TekPro, Faultmate, etc, can reset adaptive values.

Martin

 

[ptschram]

You will want to reset them after making such a repair as the engine management system is now using learned data to feed the engine and you've corrected the issue that was causing the fuel trims to be off.

No, it won't hurt anything, but you may as well start at baseline.

 

[number9]

No, it won't hurt anything, but you may as well start at baseline.

LSS, more difficult to teach old dog new tricks. Closely following some "drive cycles" called out for in manual will possibly shorten the learning curve. Obviously easier/less time to reset and one reason techs suggest doing so.
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[ptschram]

lss, more difficult to teach old dog new tricks. Closely following some "drive cycles" called out for in manual will possibly shorten the learning curve. Obviously easier/less time to reset and one reason techs suggest doing so.
......

lss?

 

[kcabpilot]

Well it came back pretty close to normal fairly quickly after a short drive. BTW it wasn't caused by contamination of the connector. I thought it was fixed when I saw the short term trim at zero but it wasn't moving, it was just switching between zero and +25 (max) the O2 sensor was dead so I had to replace it. Kind of odd because I replaced both upstream sensors about six or seven years ago, maybe 50,000 miles. I've never had to replace the downstream sensors (yet)

 

[number9]

lss?

Long story short.
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[jymmiejamz]

Well it came back pretty close to normal fairly quickly after a short drive. BTW it wasn't caused by contamination of the connector. I thought it was fixed when I saw the short term trim at zero but it wasn't moving, it was just switching between zero and +25 (max) the O2 sensor was dead so I had to replace it. Kind of odd because I replaced both upstream sensors about six or seven years ago, maybe 50,000 miles. I've never had to replace the downstream sensors (yet)

Did you pull the white piece out of the connector and clean behind that?

 

[discostew]

Gems trucks do wierd shit with fuel trim. I had a truck not to long ago somebody switched the rear o2 sensor connectors side to side somehow. One bank short trim was pos 25% the other short term was neg 25% and long term fuel trim was 0 % all the time. Never seen that before cause it's really really hard to switch those back ones. Once I figured it out all the fuel trim was coming back on its own but I reset adaptions cause I had the T4 hooked up. But I figure it would have been all straightened out after 20 miles or so.

 

[ptschram]

Gems trucks do wierd shit with fuel trim. I had a truck not to long ago somebody switched the rear o2 sensor connectors side to side somehow. One bank short trim was pos 25% the other short term was neg 25% and long term fuel trim was 0 % all the time. Never seen that before cause it's really really hard to switch those back ones. Once I figured it out all the fuel trim was coming back on its own but I reset adaptions cause I had the T4 hooked up. But I figure it would have been all straightened out after 20 miles or so.

I've switched them around frequently to try to determine if there was an issue with the cats, sensors or ECU.