rpms increase in gear idle?

[Dan636]

07 tahoe e38 ecm stage 2 btr 212/218 .480 lift shaft, been dailing in part throttle vve due to email tune being crap. i've gotten that sorted, adjusted a few things here and there since. i've noticed at random times when stopped at a light, i will hear and feel a slight bump in rpms. sometimes it happens a lot on same drive cycle, sometimes it happens once a week. finally happened while i was logging. between 4 mins and 4mins 5 secs rpm "bumps" its not a lunge, just a small enough bump to hear and feel, not really enough to make gauge move, hard to find in the log. when the event happens, i've noticed spark dropping - throttle closing, cylairmass barely moves. i'm not really sure what causes this issue, any advice for a new guy? braf table?? spark adaptives? roll it off a cliff?

[blindsquirrel]

No cats or downstream O2s (guessing, from the disabled DTCs), but Catalyst Test & Post O2 Test still enabled?

[Dan636]

No cats or downstream O2s (guessing, from the disabled DTCs), but Catalyst Test & Post O2 Test still enabled?

cats and rear o2s still installed stock everything except cam and lifters. recently stuck wide band in b1s2 position(can't weld) haven't had a chance to take it somewhere to get its on bung welded on. don't have access to the special stuff to turn off rear o2s right now, so couldn't turn code off when pulled stock sensor. so i just plugged it back in and zip tied it in the cross member out the way... i know i know not the best practice, but when you had to work late, then convince shop manager to stay later with you on a friday night well after closing time... you do what you gotta do lol

[blindsquirrel]

That explanation does not jive with what I see in your tune file.

(compared to stock 2007 Tahoe LMG file)
screenshot.30-01-2024 19.48.11.png

The Cat/Post O2 tests that are still active are here, been removed in recent versions of the editor:
screenshot.30-01-2024 19.48.44.png

[Dan636]

That explanation does not jive with what I see in your tune file.

(compared to stock 2007 Tahoe LMG file)
screenshot.30-01-2024 19.48.11.png

The Cat/Post O2 tests that are still active are here, been removed in recent versions of the editor:
screenshot.30-01-2024 19.48.44.png

okay i get it now, yes most of the common codes have been turned off. the code it keeps throwing p2a01 o2 sensor range/performance bank 1 sensor 2(greyed out can't modifiy for me). along with the typical chevy codes and aftermarket radio codes. and my editor doesn't show me those things under engine diag tab. i can see lean/rich thresholds but can't modify them. cats are still on vehicle and full evap on vehicle - the tune file that i started with is what a company left me with (a company that posts here on this forum). are you saying this could be the cause??


i've reached out to them a few times, and was assured tune was okay. so i decided to take things into my own ands and welll here i am

sorry image is sideways
20240129_175048.jpg

[gtstorey]

System to lean/rich codes being off bother me.

[Dan636]

System to lean/rich codes being off bother me.

it bothers me that they are off as well...bothers me a lot of them are off... bothers me that i paid 550 bucks to be left with it. tbh i'm afraid to turn them back on...afraid i'll get a bunch of codes and not know where to start about going to fix them.

but thats why i'm here to learn from all of you who are clearly smarter than i!

@blindsquirrel i get that you're saying the codes are turned off but the tests are still on to make the ecm look for codes, are you saying this is whats causing my issue? i have noticed that right before it sets that p2a code, wide band will read 1.10-1.12 for a bit, then drop down to .98 - .83 then the light pops up and then wide band hangs out around 1.02 or so. so i can see that its running its test trying to get the rear o2 reading to change. but this occured randomly before my wideband install...tho less random than now. forgive my ignorance please!

[LS ROB]

it bothers me that they are off as well...bothers me a lot of them are off... bothers me that i paid 550 bucks to be left with it. tbh i'm afraid to turn them back on...afraid i'll get a bunch of codes and not know where to start about going to fix them.

but thats why i'm here to learn from all of you who are clearly smarter than i!

@blindsquirrel i get that you're saying the codes are turned off but the tests are still on to make the ecm look for codes, are you saying this is whats causing my issue? i have noticed that right before it sets that p2a code, wide band will read 1.10-1.12 for a bit, then drop down to .98 - .83 then the light pops up and then wide band hangs out around 1.02 or so. so i can see that its running its test trying to get the rear o2 reading to change. but this occured randomly before my wideband install...tho less random than now. forgive my ignorance please!

Turning them on would probably the best route to take right now and let diagnostics do its thing. Then address them 1 by 1. Just a thought.

[Dan636]

Turning them on would probably the best route to take right now and let diagnostics do its thing. Then address them 1 by 1. Just a thought.

you're probably right, i'm gonna have to do the thing and spend the money to gain access to changing the emissions stuffs to change some of them tho.

[LS ROB]

You should be able to take the emissions training that will unlock those features. I don't think it should cost anything other than the credits for your vehicle unless you were talking about something else.

[Dan636]

You should be able to take the emissions training that will unlock those features. I don't think it should cost anything other than the credits for your vehicle unless you were talking about something else.

may have been confusing it with another feature thing you can unlock i will look into it and



edit to add:

the training was free i had it confused with the add your own stuff if we didn't add it feature.

[Dan636]

That explanation does not jive with what I see in your tune file.

(compared to stock 2007 Tahoe LMG file)
screenshot.30-01-2024 19.48.11.png

The Cat/Post O2 tests that are still active are here, been removed in recent versions of the editor:
screenshot.30-01-2024 19.48.44.png

i don't want to turn the cat tests off as they are still installed on vehicle - tho i can locate an older version from a local guy here in town and turn them off. i completed the training last night to be able to turn the o2 codes and all back on. i'm basically trying to make sense of what the email tuner left me with limited knowledge on the subject. i apologize if i'm being painful and an annoying noob....but at least i'm not stirring up stuff like the other guy on a recent thread....lol