Throttle Body Clean --> gas pedal vibration

[zzyzx]

I've got a 2013 Tahoe and decided to clean the throttle body last weekend. I took the TB fully off for a full clean and reinstalled. Plenty of gunk to clean out. Everything seemed to go smoothly including a quick clean of the MAF.

The idle seems to be fine, no issues with performance. But I now have a funny vibration in the gas pedal. It's most apparent at lower (1-2k) rpm. The vibration is like hair clippers under your foot. Not as strong and no sound, but similar feel. I also installed a catch can while I had the hood up, but but I can't imagine this vibration is related to that.

No codes thrown, no strange sounds with the hood up. It's more noticeable when in gear. In park, not much if any vibration. Any ideas why this started all of a sudden?

 

[zzyzx]

Quick update after spending a little time with the truck this weekend. The vibration is strongest at 700 and 1200 rpm, a little weaker in between 700 and 1200, and non-existent above 1200 rpm.

I was wrong about park. It's just as strong in park and in motion, cruising or accelerating. You can feel it in the brake pedal as well as the gas pedal, but not as much. No noticeable performance issues, but I'm going to keep an eye on gas mileage to see if that shows a change.

 

[Dank Denali]

I know when I was researching TB cleaning there is reset process that may be worth trying....google it, something like turning key to on for 60 seconds, off for 30, on for 60.

 

[zzyzx]

I know when I was researching TB cleaning there is reset process that may be worth trying....google it, something like turning key to on for 60 seconds, off for 30, on for 60.

Thanks. I'd considered that. The vibration has decreased over time, but is still there. It may be part of the relearn process, but after a month is still there. Gas mileage doesn't seem to be affected. I may try a full relearn and report back whether that shows any improvement.

 

[Jason_S]

Hate to point out the obvious, but these trucks are "drive by wire". There is no direct connection between the throttle body and the gas pedal for vibration to be transferred.

Vibration in park, vibration in drive. First thought is that it sounds like an engine mounts. Do you also have a vibration in reverse?

 

[ivin74]

Did you move anything by the fuel injectors? Sounds to me like it could me something not plugged in correctly. How many miles do you have on you truck?

 

[zzyzx]

Hate to point out the obvious, but these trucks are "drive by wire". There is no direct connection between the throttle body and the gas pedal for vibration to be transferred.

Vibration in park, vibration in drive. First thought is that it sounds like an engine mounts. Do you also have a vibration in reverse?

A valid point, but the vibration began immediately after the TB clean. Might just be coincidence but it seems related. I'll check reverse and see if that points to a motor mount instead. It seems like it's dying away slowly, but might be that I'm just getting used to it.

The first time I did the TB, I didn't replace the gasket, so I reopened and installed a new gasket thinking that maybe had something to do with it. The vibration had lessened a little by that time, but after replacing the gasket it came back full strength again.

Did you move anything by the fuel injectors? Sounds to me like it could me something not plugged in correctly. How many miles do you have on you truck?

75000 miles. When I did the TB clean I also did the MAF and installed a catch can. Maybe I bumped something loose with all that fumbling around in there. I'll double check any obvious connections (hopefully without knocking something else off).

 

[Jason_S]

Usually, vibration from bad mounts is more pronounced in drive, and sometimes reverse, and clears up some when in park.

A vacuum leak could give those symptoms, but would be accompanied by a CEL if it were that bad. The codes causing the CEL would be fuel trim codes for lean conditions, I forget the exact number and verbiage though. A bad enough air/vacuum leak can also cause a MAF or MAP code to be stored also.

There is also a relearn procedure for the TB. Sometimes the TB is sensitive about having it's position manually changed.

 

[zzyzx]

Usually, vibration from bad mounts is more pronounced in drive, and sometimes reverse, and clears up some when in park.

A vacuum leak could give those symptoms, but would be accompanied by a CEL if it were that bad. The codes causing the CEL would be fuel trim codes for lean conditions, I forget the exact number and verbiage though. A bad enough air/vacuum leak can also cause a MAF or MAP code to be stored also.

There is also a relearn procedure for the TB. Sometimes the TB is sensitive about having it's position manually changed.

Thanks for the insights. There is vibration in reverse, but also in park (but less) and even in the brake pedal. It's most pronounced when AFM kicks in on the freeway, still only at certain RPM. Maybe time to have someone look at mounts.

I considered a potential vacuum leak with the catch can but everything seems ok and no check engine light. I still need to do a thorough check through the area this weekend. It's only slightly annoying. My concern is that it's a symptom of something important.

 

[08grey]

I just put in my old intake and the same thing happened to me. I didn't touch the throttle body though.

 

[zzyzx]

Success! - vibration is 90% gone. Finally had some time to work on the Tahoe this past weekend. I removed the intake and unbolted the throttle body again, and checked around for any loose connections around the engine and found nothing.

I'm pretty sure I overtightened the TB bolts originally. I got a torque wrench and properly tightened them. I also noticed the TB was sagging a bit on the bolt points. This time I held it in place while retightening rather than let it rest on the bottom bolts. After putting everything back together, the vibration reduced significantly, and after a day or so was pretty much gone. It's still there if you really feel for it, but that's probably just normal.

I don't know if it was the bolts or something else related to taking it all off and putting back on again, but happy that annoyance is gone. Hope this helps anyone else with a related issue. Maybe overtightened bolts, sagging TB, or just jiggling a few things like you know what you're doing and put it all back together. Worked for me.

 

[zzyzx]

I just put in my old intake and the same thing happened to me. I didn't touch the throttle body though.

Makes me wonder if just reattaching the intake did it and nothing to do with the throttle body. Very possible.

 

[KenC58]

I am confused how tb problems would cause vibration in gas pedal which is electric. I have just developed vibration through gas pedal when under easy acceleration, typically at 35/40 mph.
2wd 2004 GMC Sierra. No symptoms in park/idle.
Feels like a cell phone on vibrate through my foot.

 

[Doubeleive]

I am confused how tb problems would cause vibration in gas pedal which is electric. I have just developed vibration through gas pedal when under easy acceleration, typically at 35/40 mph.
2wd 2004 GMC Sierra. No symptoms in park/idle.
Feels like a cell phone on vibrate through my foot.

highly unlikely to have anything to do with the throttle body-unless it was still dirty and causing some issue at certain rpm's therefore causing the vibrations felt in the pedal, could also be a dirty maf, dirty air filter, air sucking in the intake somewhere, or being in need of a tune-up, bad motor mount/s.
anything felt in the pedal is just like a rectifier feedback, the pedal is going to be stagnant otherwise it has no part in it that would make it vibrate.