I noticed a diminished idle the past few months, tried premium gas and that seemed to help somewhat. Today I decided to check the Map sensors - it has 3. The ones in from of the throttle body were in pretty good shape, but the one at the back of the intake looked like this:

Rather oil soaked for 44k miles. Cleaned and put back in and idle seems much improved now.

 

Clean the throttle body as well. They negatively affect idle when they are dirty. Pay special attention to the butterfly, edges of the butterfly, back side of the butterfly, and the throttle body where the two meet. Best way I have found to do it is saturate a lint free rag and wipe everything down until it's clean.

 

Is there a way to keep the Butterly from getting out of sync or mis-configured? I'm sure it's messy as well, need to study up on how best to clean & what to clean it with. thx

 

I've never had an issue when just moving the butterfly manually. That's on GM, Ford, Dodge, Honda, and Subaru. You can buy some CRC aerosol throttle body cleaner but in my experience, the alcohol saturated rag works way better and way faster.

 

Thats interesting, what engine ya got there.

 

I wonder if this doesn't make a case for an oil separator canister ?

 

2021 3.5 Ecoboost/Powerboost, 44k miles. This isn't unique to the Ecoboost, my prior GMC 6.2 throttle body was oil soaked as well prior to adding a catch can. What may be additive here is the way the Ecoboost uses the 3 Map sensors for engine management? I can for sure say the idle has smoothed out after cleaning this intake Map sensor, much better. Still might clean the throttle body, but need to make sure it won't need recalibrated if the butterfly moves during the clean.

 

The manifold MAP gets the most buildup due to the heat. That is a bright color when new. I believe orange, I clean mine a couple times a year and keep a new spare replacement. I think its condition has more to do with short drives and condensation.


The throttle MAP gets wet but not burnt,

The one by the airbox seldom gets dirty at all,

My throttle is still quite clean after 60000 miles,


I never installed a catch can, looked at them and researched them, my own conclusion is they are a waste of money and a potential source of problems. KM

 

Good to know, I plan to snag another sensor and rotate like you mentioned! Is that the input side of the throttle body? I'd guess the back side is mucky and oil/residue soaked but would need to verify.

 

I did check the back and that was clean and dry also. I just slowly/carefully opened it with my finger to inspect. No harm, but did an idle relearn after just to be complete. KM