Horrible MPG after having intake valves cleaned....looking for ideas as to why?

[jailer]

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This is from this dudes BMW but seems like he had very good results STAYING AWAY from the walnut cleaner guys:

 

[scherkey52]

I have a 2013 Rspec, I am honestly shocked at everyone's mileage ratings. I own the car for a year. But never had anything combined better than 17mpg.
I will follow this thread, since I could have the same issue. I also have a thread about my shifting issues. If someone can please take a look I would greatly appreciate it.

 

[Cali Gen]

I have a 2013 Rspec, I am honestly shocked at everyone's mileage ratings. I own the car for a year. But never had anything combined better than 17mpg.
I will follow this thread, since I could have the same issue. I also have a thread about my shifting issues. If someone can please take a look I would greatly appreciate it.

Haha I have a 3.8 and I get 15ish combined daily driving but going 80 to 85 on a 2.5 hr trip to san jose I got 28ish.. (I have full cat back exhaust and short ram intake w/ a real functioning heat shield I fabbed up a while back.) Make more power lose mpg

 

[jimmy buoy]

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This is from this dudes BMW but seems like he had very good results STAYING AWAY from the walnut cleaner guys:

Looks like something relatively easy to do myself (as long as the intake manifold isn't a bear to remove). I'm quite curious about the condition of the intake valve stems with my 5.0 GDI engine. Is it really carboned up like the BMW?
Any other members with a 5.0 already remove the intake manifold to see what their intake valves look like??

I definitely see the value of removing the plugs prior to startup to cycle the engine, avoiding possible hydrolock issues should any amount of CRC get past the intake valves and pool on the piston heads!

 

[Cali Gen]

Looks like something relatively easy to do myself (as long as the intake manifold isn't a bear to remove). I'm quite curious about the condition of the intake valve stems with my 5.0 GDI engine. Is it really carboned up like the BMW?
Any other members with a 5.0 already remove the intake manifold to see what their intake valves look like??

I definitely see the value of removing the plugs prior to startup to cycle the engine, avoiding possible hydrolock issues should any amount of CRC get past the intake valves and pool on the piston heads!

Use the seafoam spray with the straw you spray it threw your throttle body

 

[jimmy buoy]

Use the seafoam spray with the straw you spray it threw your throttle body

I’ve seen before and after pics of that method and it doesn’t get close to cleaning like this.

 

[Cali Gen]

I’ve seen before and after pics of that method and it doesn’t get close to cleaning like this.

Its. Not something you do once and forget about you do it before every oil change.

 

[jimmy buoy]

Its. Not something you do once and forget about you do it before every oil change.

That makes sense, but at this point my 5.0 has 45000 miles on it and I have no idea if the valves have major carbon buildup. Do you think that giving it a shot before every oil change now would eventually reduce and eventually eliminate buildup that may be there? It would be easier than the alternative for sure.

 

[Cali Gen]

That makes sense, but at this point my 5.0 has 45000 miles on it and I have no idea if the valves have major carbon buildup. Do you think that giving it a shot before every oil change now would eventually reduce and eventually eliminate buildup that may be there? It would be easier than the alternative for sure.

Absolutely as long as you stay consistent.
And also although premium gas is not required the added detergents defintely play a huge role in keeping carbon build up on the pistons like shell nitro or chevron with tachyon. And then the seafoam takes care of the valves over time. It's what I do and I'm at 92k never had any trouble