Checking back in. I finished the job on June 28th. It definitely needed the plugs, wires, cap and rotor. those plugs were shot! May not have been 100% necessary to do the plenum, as there really wasn't any pooling. just quite a bit of oily residue all through the intake. Took a while to get it all cleaned out.

What stinks is I have not seen even an incremental increase in my gas mileage. For how bad the plugs were I would have thought I would have gained a couple decimal points. Barely able to break 12mpg.

My drive back and forth to work is about 13 miles highway with cruise set at 65, I work 5 days a week so that's about 130 highway miles a week. Plus random city driving, probably no more than 20 city miles a week on average.

Any thoughts other things to look into? Or is this a "nature of the beast" type thing?

2001 SLT 4x4 5.9L quad-cab

 

You should be able to do better than that. Did you replace the Pre-Cat O2 sensor?

 

How are you checking the MPG's ? Not by the overhead I hope.

 

Yeah, did the sensor too. Also the 180 deg t-stat from Hughes. Pretty much everything that was recommended with the job.

The t-stat is awesome though. Engine doesn't get nearly as hot as it used to. Used to push 200deg, now much better.

Also, I'm in Iowa so I'm using the 89 octane pump gas with 10% ethanol. Here it is always at least 10 cents/gal cheaper than the regular 87 octane.

Yeah, by the overhead average. Is that not accurate? I know I'm going through the tank fast, it seems accurate.

 

The colder the engine runs , the more fuel it will use. If you had an issue with the temp using the stock 195 Tstat , I'd look into other issues if I were you.

 

just read through this whole thread again. about to rei9nstall the intake with my father. hes worried its gonna be a real bitch to get everythign lined up as we dont see any pins or anythign to line up the gasket or intake. any tricks or suggestions when putting it back in other than take your time?

as for running seafoam through it, i have a half can left, im assuming it would be better to pour it into the throttle body than use a vacuum line?

ALWAYS REMEMBER to make sure all the intake bolts are out. if you miss one at the back then try to pry off the intake, youll do what i did and break the rear corner off the intake. thank god they arent expensive

 

You are using new intake bolts right? Take a couple of the old ones and cut the heads off. Screw them in a little as guides.

 

the cut bolts worked like a charm. great idea. i also cut a slit in the top to fit a slot screwdriver, glad i did. its back on and tightened up. just finishing up the last of the connections. having a hard time figuring out where this one piece mounts on the back drivers side of the intake. thing has an electrical connection and 2 (vacuum?) lines in it. has a bracket, but for the life of me cant remember where it goes.

 

Purge valve. Right at the back of the head on the drivers side.

 

Glad I could help. I made mine long enough to unscrew them with my fingers, but if you make them too short, that slot you cut is golden.