AFM Delete and California Smog

[Dustin Jackson]

Last summer I mechanically removed the AFM from my motor and used Black Bear to tune out the AFM from the computer but I haven’t actually had to smog it yet but I assume it will be next year or so. I took it to my smog guy and told him what I had done to my tahoe (he’s a Chevy guy and is aware of the AFM delete scene) and asked him if he thought it would smog, he plugged in a OBD tester and I think he looked at the engine monitors and said “it should pass no problem”

Out of curiosity I stopped by an auto shop at the edge of my neighborhood with a couple chevys in the lot and a jasper engine sign out front.

So I stop in and find a couple mechanics and I shoot the shit with them for a bit and ask them about AFM deletes and how to navigate smog and they told me the only way I can smog it would be to buy a new PCM and reprogram my keys to it and then buy a Diablo tuner and use that to tune AFM out.

Following with their logic I asked them if I could just flash my factory tune back onto my ECU and then buy the Diablo tuner and turn off AFM that way to pass smog but they were pretty adamant that my ECU is not usable anymore and if I tried to smog with my ECU that I would get flagged and all kinds of bad shit would happen.

One mechanic was saying that the Diablo tune doesn’t flash the ECU he said “it just goes in and flips AFM off” so that the smog shop doesn’t detect the ECU has been modified.

In my situation I tuned my Tahoe with a black bear autocal and in this tune I have more modifications other than turning AFM off, I have raised the RPM a little bit and more throttle response. I don’t know how to check if the ECU has been modified but I imagine if someone checked it would show that it’s been modified.

Now I don’t fully understand how an ECU works in this context to understand what those guys were saying entirely, could you guys shed some light on the subject here? I’ve got my smog guy telling me I should be good but now I have these guys saying I’ll basically go to prison if I try to smog it.

 

[swathdiver]

Last summer I mechanically removed the AFM from my motor and used Black Bear to tune out the AFM from the computer but I haven’t actually had to smog it yet but I assume it will be next year or so. I took it to my smog guy and told him what I had done to my tahoe (he’s a Chevy guy and is aware of the AFM delete scene) and asked him if he thought it would smog, he plugged in a OBD tester and I think he looked at the engine monitors and said “it should pass no problem”

@BlackBearPerf says that their changes are not detectable.

 

[Marky Dissod]

STOP WORRYING.
If Black Bear says their changes / tunes are undetectable, I believe them - specifically because the checksums and CheckSum Verification Numbers are always addressed by a proper tune. (Go ask a mathematician what a checksum / CVN is; I get it, but my explanation will likely be inadequate.)
If this were not the case, hundreds of thousands of 'tunes' would have already been flagged by Kalephonyuh's CARB.

I'd be more concerned about passing the butt-sniffer test.
Even so, a proper tune should have enough DFCO to slide under the HC / CO / NOx thresholds.

 

[Dustin Jackson]

I see, so basically when the software is inspected it looks unmodified?

My smog guy said he doesn't even sniff the tailpipes on vehicles this "new" he would just check for check engine lights and making sure the emission monitors are set, which both pass and even he tested it himself. Also I haven't done any modifications to affect the emission systems.

I just assumed there had to be more involved in a smog check than checking for codes and emission monitors.

 

[Marky Dissod]

... when the software is inspected it looks unmodified?

When you say 'the software', you mean the state emissions inspection software?
Yes, it looks unmodified, because it was modified in such a way as to appear unmodified to a gov't computer that only checks 'Check Engine' codes and emissions readiness states.

Those arses rolling coal, on the other hand, called way too much attention upon themselves.
Yet even so, gov't computers are only - presently - verifying checksums & checksum verification numbers (besides codes and monitors).
Luckily, proper tuning software also 'tunes' checksums and checksum verification numbers so as to be undetectable.

How do you think VolksWagen Aktiengesellschaft got away with OE tunes that knew the difference between vehicular treadmills and actual roads for so many years?
Emissions inspectors are not perusing each vehicle's tune with HPTuna or EFit'salive ... yet ...

 

[petethepug]

Just have a smog shop do the test offline. You’ll know right away and no one else will be the wiser.

Good thinking on being preemptive though.

 

[Airman68]

Just the fact that the government is looking at your ECU program would be enough for me to get the heck out of there! Seriously... WTH is it their business? if you pass, who cares how you did it.

 

[Marky Dissod]

Just the fact that the government is looking at your ECU program ...

The gubbamint only looks at checksums and checksum verification numbers - and THEN ONLY of vehicles suspected by the CARB or the EPA.
They are most certainly NOT looking at entire programs - just checksums & CVNs.

 

[BlackBearPerf]

While we cannot comment on any smog testing really, we do recommend the same as if you were taking the vehicle back to the dealer. We recommend using your AutoCal to go back to factory settings and put a few miles of driving in before your inspection. We used to live in California (we have since escaped!) and of course, had our vehicles tuned and we had no issues. Without going into detail, we use every effort to ensure that there is no trace of the tune when returned back to stock.

 

[Geotrash]

While we cannot comment on any smog testing really, we do recommend the same as if you were taking the vehicle back to the dealer. We recommend using your AutoCal to go back to factory settings and put a few miles of driving in before your inspection. We used to live in California (we have since escaped!) and of course, had our vehicles tuned and we had no issues. Without going into detail, we use every effort to ensure that there is no trace of the tune when returned back to stock.

Spot on, but that strategy won't work if one has an aftermarket cam - especially one that deletes DoD and VVT. Restoring the factory tune in that scenario could cause real problems with drivability and may not even run.

I love my BB tune though and am grateful to live in a non-emission test area of a state that hasn't signed on to CARB standards.

My sense of what people are wondering is whether a BB tuned engine with an aftermarket DoD-delete cam would pass a CARB test that uses a checksum of some kind to determine the originality of the tune. My research suggests that it would fail the checksum test, even if none of the ignition and timing parameters were changed. But then again, nothing I've read is really conclusive. Some say that the tune would only fail the test if the checksum falls out of a range of acceptable values, indicating a really significant change, such as an EGR delete on a diesel for rolling coal. But I can't find anything more conclusive.