Help: MPG drop after T-belt, WP, t-stat, etc.
 

Just did my timing belt, tensioner, idler pulleys, water pump, thermostat, drive belts, crank bolt, etc...put it all back together and I'm seeing a decrease of 2 mpg over the last several tanks. I was getting ~16 mpg before doing all the work now I'm at just 14.

I considered the timing could be off but I was pretty careful when I did it and checked the marks several times...plus it runs fine (no loss of power or wierd sounds).

I did do the deckplate mod before putting everything back together and ran it with the plate off. But it is back ON now and has been for the past several weeks. Still seeing a signifcant drop in MPG http://audiokarma.org/forums/images/smilies/wtf.gif

Any help and/or troubleshooting insight would be appreciated. thanks

...should also note that coolant was flushed (toyota red) and oil was changed (cheap 5w-30)

Don't drive like an angry school girl :think:

Are you sure your coolant level is correct? (Not low). Sure that the thermostat is in the correct orientation? I'm just getting at the fact that the ECM adjusts mixture due to temperature and it could be getting thrown off by anything done to the cooling system. Doubtful but you never know.

Is your engine revving a little higher? Did you check all the vacuum hoses?

It may also be the gas you're buying. Winter gas has been known to drop MGPs.

Ok, I didn't really take this seriously because you're claiming a 2mg drop and you drive a stick, so there are many variables just within driving. I wouldn't really be concerned unless it dropped more, and it is winter time which will take more fuel at cold start to get it going.

I'm suprised you're getting 16 to begin with. Before I put my 32"s on I was getting about 18 sometimes close to 20 if I didn't drive like a pissed off teenager.

Coolant level looks fine. My gauge is kinda vague but it appears to be running at a normal temp. I installed the T-stat jiggle valve at 12 o'clock...not sure if thats correct b/c some FSM say 6 o'clock others say 12

Seems to idle the same as before, ~700 rpm. Haven't thoroughly checked vacuum hoses but from a cursory look everything appears to be securely attached. I'll do a further check this weekend...

i wouldn't be as concerned if this had happened over time or at the onset of winter gas. Seeing as my mileage dropped right after getting everything put back togehter makes me think it was something I did.

I'm making a return at the parts store tomorrow so I'll pick up some of that MAF cleaner and see if that helps

Did install the same temp thermostat as original ? A cooler one might cause it to run richer.

No change in idle quality or acceleration? If so, maybe the t-belt is off 1 tooth which would affect engine efficiency and MPG . . .

Just checked the box it came out of: 82 C (~180 F)..does that sound about right?

I have 285/75 MT's with a 3" lift and factory roof rack so 16-17 mpg doesn't seem to out of the ordinary. Will probably be going back to 265's for the next set.

I cleaned out the MAF sensor last night so we'll see if this helps...I also changed the rear end fluid (not that I expect that to help a whole lot).

Well now I know what I have to look forward to getting when I get home and put my 3" lift and rr on.

Cleaned MAF, changed fuel filter, regreased drivelines and still no change. I'm lucky to get 200 miles per tank. Now I'm at the end of the line of things to try...

I even filled up with super last tank...didn't help at all.
So I may just have to wait it out til summer gas comes around to see if thats the problem

Curious. If you might have accidently changed your cam timing. Maybe advanced it a little and it sucking a little more fuel. Don't know.