Stroked250r
May 5th, 2015, 04:02 PM
For a little background my vehicle is a 2008 5.3 and is supercharged with a tvs 1900 blower and has a higher stall converter. I fine tuned the idle using hymey's guide and had it pretty spot on since last year...this weekend I cleaned my air filter (K&N, made sure not to drench it in oil) and also the throttle body. The truck has 125,000 miles on it and the TB was pretty gunked up with carbon and oil deposits on the back side, so I cleaned it really well, using CARB cleaner which I have since read is a big no-no on these GM throttle bodies due to a coating. :doh2:
I put the intake back together, started the truck, and noticed the throttle was extremely sensitive, as in a slight blip of the throttle gave a larger rise in rpm than I'm used to seeing and it took longer to settle back down to idle. As I drove the truck around, I noticed the idle speed in parking lots was about 1100 where before it was under 800 rpm.
I disconnected the MAF, TB, reconnected everything, no change. I sprayed carb cleaner around the intake piping and throttle body and didn't notice any change in idle speed, so I don't think it is a vacuum leak.
When above 2mph and 0% APP, the truck idles quite high and doesn't settle down as before. I got to thinking, since I cleaned the carbon deposits from the throat of the TB, more air is probably entering the engine than before, so I tried to tweak the tune again using my idle tweaking tune from before but I could not get the TP% to drop below 23.9% (no air or spark corrections enabled). I'm really scratching my head here, did I mess up the TB using carb cleaner?
Attached are the tune I have been running with no changes, idle tuning tune, and some logs showing how the idle is really slow to return to 650 rpm. Timing is doing it's job as it is pulling -17 degrees to get the engine idle in check, and the TP PI controller eventually trims the TP% down to where it needs to be, I just can't get the TP% to fall below 23.9% with no corrections via tweaking B1650, B1651, B1652.
I basically need to get the max idle area (B1651 & B1652) low enough so that the engine rpm falls just above idle speed and allows the ECM to correct small idle errors, but I can't get it to respond as expected. Please help!!
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-Keith
I put the intake back together, started the truck, and noticed the throttle was extremely sensitive, as in a slight blip of the throttle gave a larger rise in rpm than I'm used to seeing and it took longer to settle back down to idle. As I drove the truck around, I noticed the idle speed in parking lots was about 1100 where before it was under 800 rpm.
I disconnected the MAF, TB, reconnected everything, no change. I sprayed carb cleaner around the intake piping and throttle body and didn't notice any change in idle speed, so I don't think it is a vacuum leak.
When above 2mph and 0% APP, the truck idles quite high and doesn't settle down as before. I got to thinking, since I cleaned the carbon deposits from the throat of the TB, more air is probably entering the engine than before, so I tried to tweak the tune again using my idle tweaking tune from before but I could not get the TP% to drop below 23.9% (no air or spark corrections enabled). I'm really scratching my head here, did I mess up the TB using carb cleaner?
Attached are the tune I have been running with no changes, idle tuning tune, and some logs showing how the idle is really slow to return to 650 rpm. Timing is doing it's job as it is pulling -17 degrees to get the engine idle in check, and the TP PI controller eventually trims the TP% down to where it needs to be, I just can't get the TP% to fall below 23.9% with no corrections via tweaking B1650, B1651, B1652.
I basically need to get the max idle area (B1651 & B1652) low enough so that the engine rpm falls just above idle speed and allows the ECM to correct small idle errors, but I can't get it to respond as expected. Please help!!
18337
18338
18339
18340
18341
18342
18343
-Keith