High rpms after throttle body cleaning

Jmac0461 · December 23, 2018

Having issues with my 2012 Silverado 5.3 after cleaning throttle body. RPMs are high cause truck to shifting problems and wanting to keep going when you get to a stop. When rev in park rpms will stay high or take forever to return to a normal idle. Need help!

Hillwood · December 23, 2018

You need to do a idle learn after the cleaning..
You need a scan tool that is able to perform it.. Try disconnecting the negative battery terminal for 5 minutes to do a reset..

Sent from my SM-G965U using Tapatalk

Jmac0461 · December 23, 2018

Thanks I’m trying that now. If that doesn’t work I’m assuming I’ll have to take to a dealer to have that done?

Dnt · December 23, 2018

I hate it when that happens. Only a few things that can go wrong right there. Could be as simple as, if you unplugged your MAF sensor assembly to remove the intake box and tube then it may require a few drive cycles to reset itself? When you put everything back together if you have a small leak anywhere in the air intake assembly it will exhibit idle symptoms. I would carefully take everything back apart and check for a cracked plastic or flex hose or ill fitting worm gear clamp, if all good then be sure that everything clamps back on securely. Another possibility is that if you were aggressively pushing the throttle body blade open by hand to do the cleaning then you may have gotten it out of calibration. You have to treat these like what they are "precision air metering devices". I would do a few drive cycles and then if problem persists take everything back apart and double check it for leaks. If throttle body is out of calibration the dealership might be able to stroke it and reset it without having to replace. Another potential problem is the MAF if it was improperly cleaned and or damaged it will also affect the idle. Only you know exactly what was done on your vehicle, hopefully this will lead you down a proper diagnostic path.

Hillwood · December 23, 2018

Thanks I’m trying that now. If that doesn’t work I’m assuming I’ll have to take to a dealer to have that done?

Yes, Unless you know someone who has a bidirectional scanner.

Sent from my SM-G965U using Tapatalk

riverbanks · December 23, 2018

Happens alot if you scan the internet, drive it,it will relearn,you think it would be instantaneous,but it's not a perfect system

Jmac0461 · December 24, 2018

I tried the whole relearn idle procedure unhooking battery for an hour, starting truck let idle for three minutes etc then do a drive cycle above 44mph more than ten miles. I drove the truck about 40 miles today. Seems to run better but when I go to slow down or come to a stop rpms aren’t where they should be and transmission isn’t keeping up with downshifting which feels like the truck wants to keep going once stopped. All I did was clean the throttle body and put back on. I’m sure I’ll have to take it to a mechanic now. Can’t believe cleaning could cause this much issues.

Edited December 24, 2018 by Jmac0461

James Elliott · December 24, 2018

I tried the whole relearn idle procedure unhooking battery for an hour, starting truck let idle for three minutes etc then do a drive cycle above 44mph more than ten miles. I drove the truck about 40 miles today. Seems to run better but when I go to slow down or come to a stop rpms aren’t where they should be and transmission isn’t keeping up with downshifting which feels like the truck wants to keep going once stopped. All I did was clean the throttle body and put back on. I’m sure I’ll have to take it to a mechanic now. Can’t believe cleaning could cause this much issues.

It's a problem with this type of system back then it was good not good now the newer generation stuff is alot quicker to respond to this type of stuff

Sent from my moto e5 cruise using Tapatalk

riverbanks · December 24, 2018

So it's getting better,not all perameters have been met,it takes 3 attempts for a fail or pass,a little longer,it will respond,and merry Christmas

redvett · December 25, 2018

Best way to clean is to turn ign. but not start engine and have someone press throttle to floor while you clean throttle body.

sixty9fordkiller · December 27, 2018

On 12/23/2018 at 10:06 AM, Hillwood said:

You need to do a idle learn after the cleaning..
You need a scan tool that is able to perform it.

^^^This.

Exact same thing happened on my 2010 Camaro SS when I cleaned it. You need to take it to the dealer and have a TECH II do the idle relearn

DBW! ts the world we live in

06SIERRAZ71 · December 28, 2018

Just drive it. My truck done the same thing yours is doing. I can’t remember the exact mileage but she got better each time I drove it. Seems like right around 100-150 miles everything was back to normal.

Jmac0461 · January 12, 2019

So I’ve been driving my 2012 Silverado for a good while now got it to start idling somewhat normal now. Seems to have a bit more power than it did before. The problem is coming to a stop it doesn’t down shift right and the other issue is the truck kinda stumbles and bogs down a bit in 6th gear. If I drop it manually into 5th gear it runs great. Any suggestions on these issues?