13.5-14 mpg on 4.0 OHV 4x4?

[oldmantruck]

Does it feel sluggish? My cat was plugged made huge difference in mileage and power

 

[chippy_69]

you know i've had that thought keep running through my mind but my buddy is a real mech. (not a driveway warrior like me) and all he sad to that was if it past emissions testing then it cant be plugged......ive yet to feel the power boost i was expecting after going from a 2.3L into my 4.0L

what can be done to further investigate a plugged cat?

 

[oldmantruck]

remove o2 sensor and run it and see of it runs better (other than the roughness from being in open loop mode all the time and the loud exhaust leak) If the sluggisness goes away your cat is probably plugged. some mechanics may have a tap that maches the o2 sensor bung to do an actual pressure check with a gauge or you can drill a small hole up stream of the cat and hook up a guage that way. You will then need to weld up the hole when done checking. I just pulled the sensor and noticed that it started better. They recomend changing 02 sensors with the cat since sluggish 02 sensors make you run rich which is what does the plugging in the first place

 

[fastpakr]

You can check the catalytic by monitoring intake vacuum rather than using the exhaust system.

 

[chippy_69]

i see, that will be worth looking into maybe over the weekend to be sure. i have a miss, nothing serious but it is missing so i would like to find the root of that problem.

 

[darkspork]

i guess when you run the numbers it sounds a little more realistic, i ahve only had it a short time as i said so its hard to tell, but whenever i have a little spare time i have being doing the minor tune up stuff, and noting mild improvements each time (im about 12 mpg now) , the next 2 priorities are fuel filter and PCV so hopefully i can reclaim some economy in those parts.

as for now i will just grin and bare it, i still got a huge 'step up' from my 93 2.3 with 315k, with the mileage, engine size and driving habits i was sitting around 15mpg, if i can get back to that point i will be happy

Let me know how big of a difference the PCV and fuel filter make, I was planning on changing those items when I have time. I'm averaging 13-14.9 allowing the truck time to warm up in the mornings.

 

[dogboy]

Back to the original post, I am REALLY surprised nobody has said anything about the part where he says it won't accelerate under 1000rpms, and doesn;t have power until 1500rpm's... That is REALLLY lugging the engine!! Unless I have been confused all my life, lugging an engine like that will severely lower the fuel mileage as well.



And, with that being said, the last 4 or 5 months, my mileage has been down around 10-12mpg, where it used to upwards of 16-17mpg. It has also had a very odd lack of power. sometimes it will be a very bad lack of power (3500rpm at 45mph on flat ground and it won't accelerate) yet sometimes it is only a slight lack of power.

I tried cleaning the injectors in my autoshop class with the injector cleaning system (NOT sea-foam), that helped slightly, but not much at all. I also noticed at that same time, that the vacuum line going to the fuel pressure regulator was not plugged in. That made more of a difference than the cleaner did. But the problem was still obviously there. So today I snagged the O2 sensors off of my parts Explorer, and stuck them on, and the problem is almost gone ( replacing the passenger's side made more of a difference than the driver's side did). Then I replaced the spark plugs. They are supposed to be gaped at .054", and the ones that were in there (6 months old, MAYBE) were all around .040". I'm going to drive it tomorrow and see if the problem is still there. hopefully the plugs finished off the problem (they were kinda nasty looking anyway)