Lost 5mpg since headgasket replacement...

Hey guys, its been about 6 weeks since you nursed me through my first head gasket change. It has been running great! Here is where the huge BUT comes in. I used to get 18-20 mpg average with mainly city driving and it has dropped to 12-14 and I am not sure why. I know its colder out and I've been starting the truck early in the morning and the winter gas mixture isn't aways the best in the northeast. Any ideas? I changed the fuel filter when I had everthing apart and it doesn't appear to be leaking, nor do I smell gas. I'm going to change the oxygen sensor hoping that it was damaged from the antifreeze cloud that made its way through my exhaust system last month. Wires, air filter, plugs, antifreeze, oil & filter, cap & rotor are all new. Tire pressure is good. Any help would be appreciated!!

 

running the same tires? have u used any fuel injector cleaner through it since the head gasket replacement?

 

One bottle of fuel injector cleaner since the tear down that I ran at a 1/4 tank for max concentration and the tires are the same.

 

i know last winter i would let my truck warm up for about 5 min's, it would get less mpg, but not -5mpg less. now i just let it warm up about 1 min.

 

I let it run anywhere from 5-10 minutes every morning, depending on the temp outside. I'm toying with the idea of upgrading my plugs to the E3's and dropping in a pro dry air filter. I'm also wondering about my fuel injectors being seriously clogged or something wrong with my fuel pressure regulator. I'm not sure what to do, the truck is running great. I hope to have the oxygen sensor in tomorrow. Hopefully that will help. Autozone wanted 120 for the o2 sensor, I got a bosch one off ebay for 35 shipped. Damn autozone!

 

Now this is just a thought. I know after I do a major repair I always think I did something to mess something else up. Is it possible your milage had dropped before this repair?

 

i have an afe pro dry s air filter, & i like it, but its not going to get ya back up to that 20mpg. have u done the deckplate mod? autozone does seem to be a bit steep on some of there parts. Chris4X4 says that the stock (denso K16R-U) r best for the engine, thats what i stick with!

 

Is it possible that one of the vacuum hoses was left disconnected, or some kind of connection was not made when putting things back together?

 

Mileage was always constant at 18-20 mpg. I'm not sure if it would be a vaccum line because it seems to be running just fine, but I'll double check them. I'm hoping that the o2 sensor replacement will get me back to normal....or at least back up to 16 mpg.

 

Keep us posted.

 

I'm not entirely familiar with the 4 cylinders, but did you verify that physical and dizzy timing is perfect? Sometimes you can be slightly off and run fine still as the computer compensates for it, but mileage will suffer.

I think the 96 model has a distributor still so that could be the issue.

Another thing that will kill mileage sometimes is the EGR system. Did you clean and check it out thoroughly during the head gasket replacement?