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I have an oo excursion 7.3 4x4, 6" lift, 33" tires, 4" exhaust wit 6" tip, and just recently switched to the napa gold 6637 air filter. I think that is about everything aftermarket I have on it. I also faithfully keep it maintained as well as the fuel filter every 4000 miles and I have 217000 on the truck. I was getting faithfully 15 mpg even pulling my boat and would only lower to 10 mpg when I towed my toyhauler. Now all of a sudden I am only getting at best 10 or 12 mpg. Anybody got any suggestions I could look into?
Ditch the lift and tires for a stock size and you will gain huge. Could have boost leaks. Look for soot around up pipe areas. Boot leaks. Could borrow a scanner and do some injector testing. Your mileage is getting close to injector time. Many things can cause loss of mileage. Usually boost related, or tired injectors.
what kind of scanner slould i look for. i have a regular obii reader, but i am sure that is no what you are talking about. i checked for leaks around all he boots and they where all good.
Ditch the lift and tires for a stock size and you will gain huge. Could have boost leaks. Look for soot around up pipe areas. Boot leaks. Could borrow a scanner and do some injector testing. Your mileage is getting close to injector time. Many things can cause loss of mileage. Usually boost related, or tired injectors.
He only has 33" tires.....Not much larger than stock. EBP and tube, I'd check that first.
I have cleaned the tube several times, but maybe it is time to change that sensor and even put a new tube in. As far as the scanner goes, I do have access to one but I am just a back yard mechanic ( or youtube might be a better up-to-date name).It is kind of Greek to me unless I could watch a video on it or some one explain it to me.
Ok, read the thread, have yet to see mention of the blow by test, has it been done yet, might reveal more to us, get the truck warmed up then put the oil cap upside down and see if it moves, hovers or putters off...
Also do the same thing with the individual wheel shafts with the hubs unlocked. If they spin, no problem. If they don't, that can be worth about .3-.5 mpg
OK, I did the oil cap and it didn't move hardly at all. So what does that mean? And the tranny and torque converter I replaced around 50,000 miles ago.
The theory on the "oil cap test" is that you put the oil cap on top of the fill tube upside down to check for "piston ring blow-by". This test is intended to be an indication of the health of the rings on your pistons, and how well they are keeping the compressed gasses from escaping past the rings. Lots of blow-by through wore out piston rings will affect your gas mileage (among other things). Problem with the test is it is not accurate or even very scientific. I would not rely on it AT ALL. You should check compression on each cylinder to determine the health of the piston rings and valves if you truly want to know if your compression numbers are good. These are good things to know at this stage of your engine's life anyway. I do have the proper tools to check for engine blow-by through the oil fill tube, but I am far from you.