Slowing down on the freeway, on the brakes, I have the signature 1200 RPM on the tach. Usually this backs off when you hit the brakes. 1200 - 1500 RPM with slight power while coasting w/o brakes applied and no throttle is normal.
However I have been getting this randomly where it won’t back off until the speed reaches 0. Popping the truck in neutral will get me 1900 – 2000 RPM w/ no throttle that slowly drops down to idle.
So freeway speed to slowing down – drop to N while stopping revs to 1900 RPM, otherwise it is 1200RPM in gear pushing me on.
Stopping with no throttle applied will flare the RPM as the trans downshifts due to speed reduction. (RPM jumps up to ~1500 between the shift.)
Slowing down in 2nd gear on a hill will reach a point where the engine decides to take off – again neutral from second gives me the 1900 RPM. This 2nd gear slowdown and take off is constant, not random.
In all cases it hangs at 1900 RPM and slows down to idle of ~600 after 20 seconds or when I come to a complete stop.
2007 SS is bone stock with 4K on the clock. No codes - No clue at dealer.
At a full stop bring your engine RPM up to 1200 and you will know what I am have to deal with stopping at times.
I had that exact same problem before but it has since been eliminated once I got the truck tuned. I understand your frustration and it pissed me off too, never really figured out what the problem was though. Just wanted to let you know that you were not alone.
"When I say Whoa, I mean WHOA!" Solution to the idle/throttle will not back off issue
Change two tables. This applies to 2007 TBSS, other years are slightly different.
Main difference is by cutting down the Final Idle Airflow Minimum vs. RPM vs. Gear.
Table #1 to change: Final Idle Airflow Minimum vs. RPM vs. Gear (This could use further reduction around 2000 RPM in 2nd gear - but works well enough now.)
Yes this looks nasty on a curve, but it works, the problem is at 1200RPM on up. I cut the entire table and the engine would start to stall at times hitting 535 RPM and having the throttle opened by the stall saver program. So I put in stock values in the idle speed area and smoothed out up to 1000 RPM. Then I broke the kneecaps out of any throttle idle air over 1000 RPM.
Whack the entire table above 600 RPM by 40%. (Select all values and multiply by .6 )
Use 6.30 for the 800 and 1000 RPM rows.
Table #2 Idle Proportional Airflow vs. RPM Error:
Get rid of the zero values in the Idle Proportional Airflow vs. RPM Error: coastdown table from -256 through the -64 RPM
Copy the normal table from -256 to -64 and paste to the Coastdown table.
Select -256 and make it 2. then multiply that value by -1 to make it negative. (I tested -1.5996 and it wasn't enough.) Do not put a "-2" in the other -256 tables like I tried. It will cause your LTFT's to go -17 the second the throttle snaps closed.
This will allow the throttle to snap closed with your foot input. No hang at 1200 RPM and slow down to idle when the PCM feels like it. Rev it in neutral and watch the RPM drop back to 650 RPM immediately.
Test this out by slowing down from 40 MPH in 2nd gear on a slight hill. DFCO will end about 22 MPH and give you a slight bump before finishing the slowdown. Without this 'fix' you will hit 2K RPM and the engine will start to take off. Neutral drop and you get 2K RPM till you stop or 30 seconds pass. With the fix the RPM will drop immediately when shifted to Neutral.
Side effects: You get a driveline 'clunk' when going from no throttle to applying throttle. From engine dragging you down to hitting the other side as you accelerate. Perhaps this clunk elimination is why these tables are so tilted to keeping some engine power on?
Change two tables. This applies to 2007 TBSS, other years are slightly different.
Main difference is by cutting down the Final Idle Airflow Minimum vs. RPM vs. Gear.
Table #1 to change: Final Idle Airflow Minimum vs. RPM vs. Gear (This could use further reduction around 2000 RPM in 2nd gear - but works well enough now.)
Yes this looks nasty on a curve, but it works, the problem is at 1200RPM on up. I cut the entire table and the engine would start to stall at times hitting 535 RPM and having the throttle opened by the stall saver program. So I put in stock values in the idle speed area and smoothed out up to 1000 RPM. Then I broke the kneecaps out of any throttle idle air over 1000 RPM.
Whack the entire table above 600 RPM by 40%. (Select all values and multiply by .6 )
Use 6.30 for the 800 and 1000 RPM rows.
Table #2 Idle Proportional Airflow vs. RPM Error:
Get rid of the zero values in the Idle Proportional Airflow vs. RPM Error: coastdown table from -256 through the -64 RPM
Copy the normal table from -256 to -64 and paste to the Coastdown table.
Select -256 and make it 2. then multiply that value by -1 to make it negative. (I tested -1.5996 and it wasn't enough.) Do not put a "-2" in the other -256 tables like I tried. It will cause your LTFT's to go -17 the second the throttle snaps closed.
This will allow the throttle to snap closed with your foot input. No hang at 1200 RPM and slow down to idle when the PCM feels like it. Rev it in neutral and watch the RPM drop back to 650 RPM immediately.
Test this out by slowing down from 40 MPH in 2nd gear on a slight hill. DFCO will end about 22 MPH and give you a slight bump before finishing the slowdown. Without this 'fix' you will hit 2K RPM and the engine will start to take off. Neutral drop and you get 2K RPM till you stop or 30 seconds pass. With the fix the RPM will drop immediately when shifted to Neutral.
Side effects: You get a driveline 'clunk' when going from no throttle to applying throttle. From engine dragging you down to hitting the other side as you accelerate. Perhaps this clunk elimination is why these tables are so tilted to keeping some engine power on?
Not gonna help, that's the way she works.
Warwagon's first post is a bit scary, I think his truck is slow in responding, but idk.
Looking for an answer to this problem is how I found this site a couple of years ago.
No one has given me a satisfactory answer as to why gm programed it this way (lots of guesses).
I am surprised the brakes last as long as they do. I not surprised that they don't stop as well as they good.
I can't understand how protection agencies would permit this programing.
I have this same problem. I also have the Superchips Porgrammer and it didnt fix it. I read somewhere else it might be there to keep the drivetrain sinched up so you dont get the driveshaft clack if you start to accel after you left off. It is really freaking annoying and has almost cost me to hit someone. My next tune will definately address this issue.
mine is a 07 ss and it does the same thing when coming to a full stop the engine will keep pushing at like about 1000 rpms and it goes down realy slow ,
did any body found a solution for this issue.
This happend tome about a month ago just for one trip (about an hour or so worth) thought it was a sticky throttle body so I had top engine cleaner and cleared it out.. and so far I havn't had any issues. but it has been mentally noted.
mine does that too, and randomly :duh: theres no patren for it, just some tims and suddnly out of the blue the riv will jump to 900-1000rpm and i'll have to JUMP on the brakes ! :bonk:
btw i use to have 450 Kilometeres on a full tank, after my 20's and a new fan clutch i get 350 !!!! what gives ? any ideas ??? :sadcry:
hey thanks for taking some time to answer me pal :tiphat but the thing is i cant :no: it'll cost time and money to get that done, i hardly got my tune done, so thats not an option :worried: not to mention its fine but sometimes does that :duh: thanks any way pal
My 04 envoy xl just started this after i cleaned the trottle body, run the a/c and u'll run a light if ur not on the brakes HARD, same nuetral hits 2000rpms...really sucks this nice of a truck has so may flaws :no:
My 04 envoy xl just started this after i cleaned the trottle body, run the a/c and u'll run a light if ur not on the brakes HARD, same nuetral hits 2000rpms...really sucks this nice of a truck has so may flaws 🇳🇴
well after a 800 mile trip to southern kentuky n back it is a little better, but she still pushes with ac on until u drive about 15 mins around town then it backs off a little, nuetral revs to about 1500 rpm...i know they are programmed to keep the trottle on some with speed to keep up the "slack" in the drive line too but its still a little high....
stays steady...actualy it has never gone past the middle mark yet! it was 90+ today and i ran the ac all day as the fam and i went outta town and it kept pushin the same all day but, once it drops under about 15 mph it seem to back right off....if ur going 25-30 mph its like havin the cruise set :no:
Having similar issue with my '06 SS. Throttle hangs at about 1200 rpm. Seems to be worse since having the tune done. I have found in my case that if I shift to neutral when it hangs it returns to idle quickly but once I put back in gear rpms again go up to 1200. This really sucks because it seems to do it about half the time!!
Ok Mine after you come to a stop and you let it came down to idle just tuch the gas and it gos to 1500 and starts climing to arond 3000 Dont know what to do about it. Just bought it and havent had it for more than 40 miles. Its an 07 5.3. When your going down the road and left off the gas it keeps going like cruse.
Frustrated
It's been a while since a reply on this issue. I'm hoping some new revelation has surfaced. I have these same issues. Tried a lot of solutions to no avail. Anything new?
Newb here trying to revisit this topic.
I just got an '02 Envoy thats kind of doing this. I was hoping someone could tell me if my issues are normal or a different problem.
It won't slow down hardly when i take my foot of the gas while moving and when I put in neutral while moving it idles at 1500 rpm.
When I stop though it feels like it is struggling to keep 500 rpm like the torque converters locked up but maybe these 2 issues aren't related. The weird thing is, I bought this from my brother that said the problem just started about a year ago with 155000 miles on it.
Any insite will help. Thanks
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