Well, I was inspired by mdxforever's post, and since I was tired of getting 17-18mpg averages (dropped suddenly from 21-22mpg), I decided to go ahead and clean my intake as well. Mine actually looked worse than his! Several of the grooves were completely blocked, and all of the intake holes were 50-90% blocked with carbon and sludge residue.
- Reminds me of what plaque buildup in arteries must look like...
I basically sprayed some throttle body cleaner on each part, and let it soak. What was remaining, I scraped off with a screwdriver, and sucked up as much as I could with a shop vac. I used paper towels to soak up the pools of oil on top of the intake ports.
I also took the time to check the EGR valve (which seemed fine, as the plunger worked freely, and there was not much carbon buildup at all), as well as replace the PCV valve. The old had quite a bit of oily junk on the plunger, and just looked tired. I figured, for a $4 part, I might as well just change it out. The replacement had a bit different angle on the end (a 90 degree bend, vs. the 45 degree bend that the stock one had), but it didn't seem to make a difference, other than the fact that the hose had to bend a bit more to connect.
During this entire process, I disconnected the negative battery terminal to reset the ECM. Someone here mentioned that once the battery was reconnected, that you should allow the computer to set the idle speed by letting the car idle without load (no AC) until the radiator fans kick on twice. I did this, and then took it for a drive.
My MPG average for the same daily drive route climbed back up to 21mpg! Not only that, but the car runs SO much stronger now. No more surging during heavy acceleration, and it seems to have it's "oomph" back. I guess I should not be surprised, considering what the intake looked like... it was like the engine was trying to breath through pinholes... I think that the mpg may even get better, considering the ECM may need some time to learn my driving habits all over again.
The MDX currently has 96K on it, and it seems stronger than when we bought it at 45K... Not bad!
Thanks for the great thread!