Range AFM Delete and Emissions

[Sparksalot]

I’ve seen other people comment about AFM engaging while cruising at highway speed while towing.

I did notice while in manual mode, that AFM was inhibited in 1-5, but would still come on crushing in 6. That was the reason I splurged for a device in each of the twins.

 

[89Suburban]

I have been driving around with tow mode, while the Range device is out, to force V8 mode (poor man's AFM disable). I was hoping I could complete the ECU's Trip criteria and get the readiness flags that appear to be set when I remove the Range dongle, to understand how much driving I actually have to do to ready the car for emissions testing, all the while, not running in AFM mode.

Today I had a kind of disheartening occurrence as while in two mode, I glanced down and the AFM system was functioning like normal, switching between V4 and V8 mode! Somehow, it seems the ECU got confused about tow mode and didn't disable AFM mode.

I looks like it won't be a reliable strategy for forcing AFM disable while driving the trip criteria miles before an emissions test.

I haven't had the opportunity to do the exact GM Trip test, but so far, around town and a tiny bit of freeway driving, 25 miles and counting, the flags are still set.

Kick ass thread!!!!! Bill, if you can try to set your trip odometer to see how many miles until it clears if you remember. Great job here! Let me know if you need me to guinea pig anything to back your guys tests. I don't have the scan tools but I can to some driving tests if you need.

I am curious about your AFM kicking in during tow/haul mode, I might check mine out tonight to see if it does that on mine. I would assume it would if yours did. I just never noticed if it did but I never did tow/haul without the dongle before.

 

[wsteele]

Kick ass thread!!!!! Bill, if you can try to set your trip odometer to see how many miles until it clears if you remember. Great job here! Let me know if you need me to guinea pig anything to back your guys tests. I don't have the scan tools but I can to some driving tests if you need.

I am curious about your AFM kicking in during tow/haul mode, I might check mine out tonight to see if it does that on mine. I would assume it would if yours did. I just never noticed if it did but I never did tow/haul without the dongle before.

I had set the trip odometer the last time I pulled it, so I will know how many miles it takes (if they actually do reset one of these days... :0). I know there are a lot more criteria than just miles, so I have a little pad and am noting start cycles to full temp, how much time on the freeway, etc.

After this one is complete and they are all reset, and when I have clear day when I can do the exact GM Trip cycle, I will test it to see if it will clear them in one trip. The document says the prescribed test should only take 15 minutes of driving. We shall see.

I was pretty disappointed that Tow Mode didn't seem to be reliable as a disable. I had tried it on two previous short trips and it seemed to work reliably (I actually did multiple foot off the gas cycles on each trip to assure I would be triggering V4 mode, if it was going to kick in and it never did). It was just this morning, after a short stop, I started it up, pushed tow mode, had the the little trailer light on in the cluster and drove off. Maybe 3 minutes later, as I was slowing for a stop sign, I looked down and the instantaneous display showed V4! Ack!. I then watched it shift from V4 to V8 mode and back, just like AFM was running normally. I have no explanation for why it decided to use AFM mode while in Tow Mode.

Any tests you decide to do to contribute to the experience DB would be welcome. For me, I know the puzzle will always have some pieces missing, but I would just like to get as many pieces in the puzzle as possible. Right now, I don't think I even have all the edge pieces in.

 

[iamdub]

AFM is primarily load-based. Tow mode or not, if the engine isn't under X amount of load, AFM is gonna engage. All tow/haul does is alter the transmission's shifting RPM and shift firmness. Maybe shift speed as well.

 

[wsteele]

AFM is primarily load-based. Tow mode or not, if the engine isn't under X amount of load, AFM is gonna engage. All tow/haul does is alter the transmission's shifting RPM and shift firmness. Maybe shift speed as well.

I had read somewhere on the interwebs that tow mode disengaged AFM. I knew it had to be true, so I tested it...

The funny thing was in a few short trips, with the tow mode engaged, even on a flat stretch, lifting off the gas, it stayed in V8 mode. I did this quite a few times and it never shifted to V4.

Today, things didn’t work that way.

 

[wsteele]

So, just an update. I got a chance to do the prescribed GM Universal Trip, described in post #6. I drove it pretty much exactly as spelled out, including annoying someone behind me when I was doing the brake off deceleration parts, even with the emergency blinkers on, on a 6 lane freeway, in the right lane, this guys was extremely annoyed I was slowing in front of him. Zero traffic, so passing me would have been a breeze. Geesch.

Anyway, results are the readiness flags are still not clear. The trip description does spell out that if the cats are weak or the battery disconnected, it may take up to five driving cycles to clear the flags. I know the battery wasn't disconnected (but maybe the Range device sets a flag that says it was, probably will never know if that is the case), so I am assuming my cats are weak (given they are originals, not a reach to conclude that) and will keep doing the driving cycles for a few more days and see if they clear.

An update to the Tow Mode effect on AFM. I can now say with authority, Tow Mode does not shut AFM off. The error of my previous tests that made me conclude it did (other than a very authoritative post on the internet that it did shut it off, and maybe some confirmation bias on my own part, wanting it to be true) was that AFM works only in 3rd and 4th gear (for sure in tow and likely always), with this transmission. My tests that misled me were around town in Tow Mode where I never got out of 2nd gear (like 30 mph and below), hence V4 was never engaged when letting off the throttle. In Tow Mode and clearly in regular mode, lifting the throttle in 3rd or 4th engages AFM. A tiny bit of clarity on a cloudy day.

 

[89Suburban]

So, just an update. I got a chance to do the prescribed GM Universal Trip, described in post #6. I drove it pretty much exactly as spelled out, including annoying someone behind me when I was doing the brake off deceleration parts, even with the emergency blinkers on, on a 6 lane freeway, in the right lane, this guys was extremely annoyed I was slowing in front of him. Zero traffic, so passing me would have been a breeze. Geesch.

Anyway, results are the readiness flags are still not clear. The trip description does spell out that if the cats are weak or the battery disconnected, it may take up to five driving cycles to clear the flags. I know the battery wasn't disconnected (but maybe the Range device sets a flag that says it was, probably will never know if that is the case), so I am assuming my cats are weak (given they are originals, not a reach to conclude that) and will keep doing the driving cycles for a few more days and see if they clear.

An update to the Tow Mode effect on AFM. I can now say with authority, Tow Mode does not shut AFM off. The error of my previous tests that made me conclude it did (other than a very authoritative post on the internet that it did shut it off, and maybe some confirmation bias on my own part, wanting it to be true) was that AFM works only in 3rd and 4th gear (for sure in tow and likely always), with this transmission. My tests that misled me were around town in Tow Mode where I never got out of 2nd gear (like 30 mph and below), hence V4 was never engaged when letting off the throttle. In Tow Mode and clearly in regular mode, lifting the throttle in 3rd or 4th engages AFM. A tiny bit of clarity on a cloudy day.

Good job boss keep it up.

 

[PG01]

So, just an update. I got a chance to do the prescribed GM Universal Trip, described in post #6. I drove it pretty much exactly as spelled out, including annoying someone behind me when I was doing the brake off deceleration parts, even with the emergency blinkers on, on a 6 lane freeway, in the right lane, this guys was extremely annoyed I was slowing in front of him. Zero traffic, so passing me would have been a breeze. Geesch.

Anyway, results are the readiness flags are still not clear. The trip description does spell out that if the cats are weak or the battery disconnected, it may take up to five driving cycles to clear the flags. I know the battery wasn't disconnected (but maybe the Range device sets a flag that says it was, probably will never know if that is the case), so I am assuming my cats are weak (given they are originals, not a reach to conclude that) and will keep doing the driving cycles for a few more days and see if they clear.

An update to the Tow Mode effect on AFM. I can now say with authority, Tow Mode does not shut AFM off. The error of my previous tests that made me conclude it did (other than a very authoritative post on the internet that it did shut it off, and maybe some confirmation bias on my own part, wanting it to be true) was that AFM works only in 3rd and 4th gear (for sure in tow and likely always), with this transmission. My tests that misled me were around town in Tow Mode where I never got out of 2nd gear (like 30 mph and below), hence V4 was never engaged when letting off the throttle. In Tow Mode and clearly in regular mode, lifting the throttle in 3rd or 4th engages AFM. A tiny bit of clarity on a cloudy day.

Don’t think about your cats, they’re fine. That monitor takes the longest to reset. All those steps are just a suggestion, normal driving for a few days to a week will put the vehicle in all of those ‘parameters’.
It will reset, give a few more days of drive cycles. Drive cycle meaning cold start and take a normal drive.

When I originally put my range on my 13 I never thought about it causing a fail inspection and pulled it right before I went for an inspection.
Realizing I’m a moron, I drove around for another week without it and got it passed.

Not sure if it was mentioned but NY you can have 1 (or 2??) monitors not ready and pass.

I went through this with my fil’s pos 02 suzuki aerio just last summer because I let the battery die. I drove around for 4 days before work, got them all ready except 1 or 2 and went and passed.

good luck on your ‘quest’

 

[89Suburban]

Don’t think about your cats, they’re fine. That monitor takes the longest to reset. All those steps are just a suggestion, normal driving for a few days to a week will put the vehicle in all of those ‘parameters’.
It will reset, give a few more days of drive cycles. Drive cycle meaning cold start and take a normal drive.

When I originally put my range on my 13 I never thought about it causing a fail inspection and pulled it right before I went for an inspection.
Realizing I’m a moron, I drove around for another week without it and got it passed.

Not sure if it was mentioned but NY you can have 1 (or 2??) monitors not ready and pass.

I went through this with my fil’s pos 02 suzuki aerio just last summer because I let the battery die. I drove around for 4 days before work, got them all ready except 1 or 2 and went and passed.

good luck on your ‘quest’

Thanks PG01.

 

[PG01]

Thanks PG01.