So i have been searching and cannot find any information on this. My wife has an 08 fit sport automatic and it gets poor mileage and has poor power. We have also had to replaced the plugs every 30k due to cyl 4 running hot. I was wondering if the 09 and up upper intake manifold is a direct bolt on and if its design would help with any or all of these issues.

Thanks!

 

It is NOT a direct bolt-on.

How many miles are on the vehicle? It sounds like you are having some serious problems with the engine. I've never heard of those types of issues before.

 

Just over 60k, if she isn't driving it in sport mode and controlling the shift points it only gets 23-25mpg with a good bit of her driving being highway...

 

If only #4 is running hot, you may have a valve clearance issue.

What other steps have you taken to address this issue?

Do you replace the plugs at 30K if misfires begin? Are you using Iridium plugs?

 

Cant troubleshoot any engine the ignition is weak.

Plugs (Stock)
Coils (If they have near or over 80K
Valve Adjust.

Then troubleshoot.

FYI MY 07 Sport Auto around town gets about 28 at best.
I run in the 25MPG range a lot as well.

 

First impression of valve adjustment needed. I would have it done first.

 

OP:
What makes you to conclude that the cylinder one runs hot (perhaps white spark plug)?
The cool idea is to hookup OBD-2 scanner and check the live data as engine runs!
If engine has normal valve clearance and no cylinder specific misfire, I would take a look on the EGR valve too (not closing completely and causing "higher than normal load" MAP reading)