Wierd surging issue, follows the O2 sensors swinging like they are overcorrecting

[GrannySShifting]

LTerms are stable, but you can hear and feel in the car surging cruising down the road in time with the oscillation you see from the STrims?

Not sure what you can do to reign in the O2s or the fueling effect they have, or if this file is OEM in the regard or someone had been screwing with switching valvues or other stuff, it was heavily moddified and (and screwy) when I got it. Have most of the issues figured out, on the home stretch now LOL

[GHuggins]

Need to tune in your O2's..........

Proportional multiply by something like .835. Integrator delay multiply by 1.1 or higher until your actual air fuel matches commanded as long as commanded is 14.55 or higher. May have to tweek O2 mv settings to 550mv vs airflow as well... Do all of this while holding ellevated rpm's around 1500 or so. That way your cam doesn't screw with the readings...

[GrannySShifting]

There is no integrator delay...

[GHuggins]

Try the proportional, otherwise you'll need to request they be added via tech assist.

[GrannySShifting]

Try the proportional, otherwise you'll need to request they be added via tech assist.

I have, about 60% now on prop no change

[GrannySShifting]

Any other ideas? Your suggstion on changing the prop values have had 0 effect

[GHuggins]

Have you tried going the other way? Without the delay tables I'm not sure if you can adjust or fix the problem fully.

[GrannySShifting]

Have you tried going the other way? Without the delay tables I'm not sure if you can adjust or fix the problem fully.

Went the other way, tried all the way up to 150% of original value. Still surges. may be SLIGHTLY better, but very noticeable still. Open loop no fucking problem. Dumb truck pcm. Really close to disabling oxygen sensors up until 2000 rpm or so

[will15]

Had the same problem with a ls1 would surge bad around 70km tried every thing for months, then I played with the closed loop vs airflow mode. With yours it is a bit different you have closed loop proportional base vs airflow, with the ls1 I kept reducing the hole table until the problem was gone and now it drives so sweet, as far as I know it has changed the way the computer routines the 02 settings for that particular airflow mode. I put a post about this awhile ago but I don't think any one else had the same problem, I thought it was due to long tube headers and the placement of the 02's.

[GHuggins]

Had the same problem with a ls1 would surge bad around 70km tried every thing for months, then I played with the closed loop vs airflow mode. With yours it is a bit different you have closed loop proportional base vs airflow, with the ls1 I kept reducing the hole table until the problem was gone and now it drives so sweet, as far as I know it has changed the way the computer routines the 02 settings for that particular airflow mode. I put a post about this awhile ago but I don't think any one else had the same problem, I thought it was due to long tube headers and the placement of the 02's.

So you more or less "really" reduced this table? Wondering if you couldn't dang near zero it out for the ones that don't have the integrator delay table to modify?

[will15]

I don't know about zeroing it all out but I would try slowly reducing it and see what happens, if you zero it out the 02's might not switch properly. I am just not 100% sure what the numbers represent in this table. Any thoughts any one else. Give it a crack and let me know.

[Nate007]

Wss going to start another thread to ask/discuss this one, but since the topic is being discussed here, I'll start here first.
I'm having the same issues with my '10 Camaro, and it's got a big cam and a KB 2.8 on it. I can feel the during while cruising down the road -very annoying at times.
I stumbled across this video, but haven't finished it yet. Made it about 10 minutes into it before getting distracted (ie :"squirrel!"), but there was an interesting lesson on proportional fueling and the "why" behind it. The rich/lean switching is for nothing more than to provide the catalytic converters with the chemical reaction they need to operate. (NOx & O2). The rich swing adds the fuel in the exhaust, and the lean adds the oxygen for proper ignition in the cats, and that was it. They're teaching that is purely an emissions thing, and the ecu ignores the switching for normal fueling(engine operation) functions. That was not why I always assumed the 02's switched like that, but this makes perfect sense.
I'm not sure if everyone in this discussion still runs cats on their cars, but I don't, and was wondering about just shutting the proportional fueling off? I have Kooks LT's w/3" exhaust, and literally melted the elements out of the cats when getting the car dyno tuned. Had to cut them apart and dig the chunks out, some if which were lodged in the x pipe.. Now the cats are hollow and I was told by Kooks (even though I'm a dealer for them) that they won't warranty their cats on a supercharged car.... WTF... Had about 300 miles on them.
Anyway.. There's a very informative discussion on this video, but check it out and see if you agree? The part I'm referring to is around the 10:00 mark in the video. Is there any arguments to it's validity? Most all of the LS tuning I do is on non-catalytic equipped cars, and older cars that have LS engines swapped into them. If this is true, I could almost eliminate the proportional fueling and gain better mileage and power, and be easier to tune?


https://youtu.be/oRX2V6_a3dc

[GrannySShifting]

Wss going to start another thread to ask/discuss this one, but since the topic is being discussed here, I'll start here first.
I'm having the same issues with my '10 Camaro, and it's got a big cam and a KB 2.8 on it. I can feel the during while cruising down the road -very annoying at times.
I stumbled across this video, but haven't finished it yet. Made it about 10 minutes into it before getting distracted (ie :"squirrel!"), but there was an interesting lesson on proportional fueling and the "why" behind it. The rich/lean switching is for nothing more than to provide the catalytic converters with the chemical reaction they need to operate. (NOx & O2). The rich swing adds the fuel in the exhaust, and the lean adds the oxygen for proper ignition in the cats, and that was it. They're teaching that is purely an emissions thing, and the ecu ignores the switching for normal fueling(engine operation) functions. That was not why I always assumed the 02's switched like that, but this makes perfect sense.
I'm not sure if everyone in this discussion still runs cats on their cars, but I don't, and was wondering about just shutting the proportional fueling off? I have Kooks LT's w/3" exhaust, and literally melted the elements out of the cats when getting the car dyno tuned. Had to cut them apart and dig the chunks out, some if which were lodged in the x pipe.. Now the cats are hollow and I was told by Kooks (even though I'm a dealer for them) that they won't warranty their cats on a supercharged car.... WTF... Had about 300 miles on them.
Anyway.. There's a very informative discussion on this video, but check it out and see if you agree? The part I'm referring to is around the 10:00 mark in the video. Is there any arguments to it's validity? Most all of the LS tuning I do is on non-catalytic equipped cars, and older cars that have LS engines swapped into them. If this is true, I could almost eliminate the proportional fueling and gain better mileage and power, and be easier to tune?


https://youtu.be/oRX2V6_a3dc

How would you eliminate just the prop part of closed loop operation?

[GHuggins]

This was originally posted by Michael D back in 2013....

(These two tables affect the % fuel needed for proper closed loop response and start the STFT process

Closed Loop Proportional Base vs. Airflow Mode: This table returns the base proportional % fuel change. Proportional base rate table is the primary amount of fuel needed to drive the closed loop fuel control into oscillation. Proportional fuel acts like an on/off switch to keep the fuel moving around the current O2 Rich/Lean vs. Mode table set point. The values on the Proportional Table add or subtract to the base fuel rate depending on the previous fuel condition (i.e. if rich then switch lean, if lean the switch rich). The amount of fuel to add or subtract increases with the airflow mode and should be based on injector size and % fuel switching needed.
Closed Loop Proportional Gain vs. O2 Error: This table returns a multiplier value for the increase/decrease of the base rate table. A multiplier value of 1.000 will have no effect on the proportional base rate. If the difference between the current O2 reading and its desired value from table O2 Rich/Lean vs Mode (the current Fast O2 error) is large the VCM will need to change the proportional fuel a lot. If the error is small, it should change it only a little to continue oscillation without undershoot or overshoot. Undershooting will cause the Closed loop fuel to become sluggish or miss the current O2 Rich/Lean vs. Mode table set point. Overshooting with cause the engine to vary excessively in RPM. )

Going off of this, one would think that all you would need to do is (0) out the proprotional gain table for the O2's to elliminate the O2's ability to add or subtract fuel for "switching"?

[will15]

This was originally posted by Michael D back in 2013....

(These two tables affect the % fuel needed for proper closed loop response and start the STFT process

Closed Loop Proportional Base vs. Airflow Mode: This table returns the base proportional % fuel change. Proportional base rate table is the primary amount of fuel needed to drive the closed loop fuel control into oscillation. Proportional fuel acts like an on/off switch to keep the fuel moving around the current O2 Rich/Lean vs. Mode table set point. The values on the Proportional Table add or subtract to the base fuel rate depending on the previous fuel condition (i.e. if rich then switch lean, if lean the switch rich). The amount of fuel to add or subtract increases with the airflow mode and should be based on injector size and % fuel switching needed.
Closed Loop Proportional Gain vs. O2 Error: This table returns a multiplier value for the increase/decrease of the base rate table. A multiplier value of 1.000 will have no effect on the proportional base rate. If the difference between the current O2 reading and its desired value from table O2 Rich/Lean vs Mode (the current Fast O2 error) is large the VCM will need to change the proportional fuel a lot. If the error is small, it should change it only a little to continue oscillation without undershoot or overshoot. Undershooting will cause the Closed loop fuel to become sluggish or miss the current O2 Rich/Lean vs. Mode table set point. Overshooting with cause the engine to vary excessively in RPM. )

Going off of this, one would think that all you would need to do is (0) out the proprotional gain table for the O2's to elliminate the O2's ability to add or subtract fuel for "switching"?

If you did that wouldn't it stop the rich then lean condition from short term fuel trims that drive the 02's into oscillation, if you wanted to go that way you might as well go open loop tune. I would try reducing the whole closed loop proportional base vs airflow table by a 10-20% and see if it helps, I think what happens the ecu is adding then subtracting to much fuel to drive the 02's into oscillation that's why you can feel the surging from the short term trims.

[will15]

I all so found the closed loop mode vs air flow mode table it is hidden on the left hand side all the way down the bottom, I would just try reducing the hole table like I did. it's worth a shot.

[Michael_D]

Hu? The ECM intentionally adds and cuts fuel to get the O2 sensors to oscillate? What would be the purpose of that?

[schpenxel]

Hu? The ECM intentionally adds and cuts fuel to get the O2 sensors to oscillate? What would be the purpose of that?

Nobody knows!

It's like they have these sensors that are only really useful over and under stoich, and like they have this thing catalytic converter thing that needs some fuel and oxygen to do it's thing or something.

[schpenxel]

In all seriousness.. neither of these tables are available to E40's. I wonder if HPT can add these for me/us? I can feel the oscillations on mine as fuel trims cycle

[Michael_D]

In all seriousness.. neither of these tables are available to E40's. I wonder if HPT can add these for me/us? I can feel the oscillations on mine as fuel trims cycle

You'd have to send support an email asking if they can look into it. You will also need to send them your file, so they can verify whether or not GM included the programming. If GM did not, then HPT cannot add it.... I just went through that exorcise, asking if they could add the "Closed Loop Proportional Gain vs. O2 Error" table to my operating system (E38). The response was "Sorry, we can't add it".