My 02 Dingo (4.7) seems like it is bogging off the line and I notice when I let off the gas the rpms drop abruptly. Recently I replaced the stock champions with new stock champion plugs, the TB is clean, I replaced the IAC motor, and ran some Techron through the tank. I was going to pull the O2 sensors but they are like rusted on so tight I couldnt budge them. Truck has 55k miles on it. Any ideas on what it might be?

 

To get those o2 sensors off use a little pb blaster or wd40. You may want to pull the plugs and take a look at the tips to make sure they aren't fouled up, Other than that I think some new wires, a cap, and rotor are in order.

 

It's a 4.7 so no cap, wires, rotor. It has the coil packs. Do those ever need replacing?

 

Oh I didn't see that part of your post sorry.

 

Coil packs don't usually need replaced but the plugs do. Use the stocker Champions or the same range in the NGKs. My bet it the TPS or a loose TB cable.

IndyDurango

 

When I get a chance I am going to pull a couple of plugs to see what they look like. I was also thinking about the TPS. I might try replacing it to see if it makes a difference.

 

Ok, so here is what I have done. I replaced the TPS, ran the seafoam through the engine, changed the oil, pulled the champion plugs (which looked pretty good) and replaced them with new NGK's, cleaned and re-oiled my air filter and still no noticeable difference. Even after doing all of that and replacing the IAC as well, the idle still seems too low(around 500 rpm at NOT) and the power just isnt like it was. She seems to be fighting herself when accelerating and when I let off the gas the rpms drop suddenly. Any other ideas? Truck has 58K miles, so I wouldnt think it could be an O2 sensor or plugged cat. How can I check those? Any other sensors I should look at? Vacuum leak? When I start the truck and it's cold the idle seems good and the power is there, but after it warms up, not so much.

 

Check to see if you have enough fuel pressure to push the fuel thru the injectors. I seen some users posting something like this can cause power loss as well?

 

Sorry, I am not that gifted mechanically. How would I check the fuel pressure? Also, upon further inspection I just noticed a couple of small holes in the exhaust pipe before the muffler. Would this make an impact on performance?

 

You can purchase a fuel pressure gauge and connect to the fuel rail I think. Otherwise, take it to a reputable mechanic to have the fuel pressure checked.