Already misdiagnosed it once, bail me out fellas!!

[94Jo]

Lately, my navajo started to be very sluggish. I couldnt get it over 3000 RPMs to save my life. I felt/heard a backfire sort of thing from what sounded like the lower part of my engine/exhaust. And the worst thing is that I now get around 9 or so mpg. It sounded like a dragging rattle can underneath me as well. I assumed I had clogged cats, I had them removed yesterday and my appointment for the ehaust shop is today, but while driving around I can still hear/feel the backfire-ish thing and my power still sucks. It is really my lower rpm torque that makes it studder hard, like going into OD it stumbles and struggles. What is it guys? Sparkplugs? Wires? O2 sensors? These are my top guesses, waht are yours. This site has helped me out a lot, and now my dumbass is cat-less and has to dump money into an incorrect diagnosis. Thanks in advance!!

 

[boggs1227]

i'm going to say plugs and wires ,how many miles on the engine? and is it a backfire or a "ping" your hearing ? bad mpg...is the exhaust real bad sooty ? if so then maybe the "fpr" (fuel pressure regulator) has gone bad as well ,this will give you "real crappy mpg " but all that you described sounds like fuel air management problems.

 

[Premier]

check your fuel pressure

 

[94Jo]

I have already checked my fuel pressure and it was fine, the backfire is like a loud pop that happens as the rpms raise. When I floor it (not that I do it often) the pops are one after another and it feels as though I am tapping the brakes. I guess i will do plugs and wires next. 135K on the motor, any other guesses?

 

[DrtDvl90]

i had a similar problem with my X with 105xxx miles, check your plugs mine were completely shot as soon as i changed them everything was good again

 

[Kamel]

Had a similar problem with my old jeep. The problem with the jeep was a restricted exhaust. I don't know how you'd check, but if there's a way to see if your exhaust is being restricted I'd try that. Despite all of that, it seems like either a basic tune-up is in order, or it is a restriction of intake/exhaust somewhere.

 

[Tbars4]

...Have you tried reading your codes???..How many miles since your last tune-up???:scratch:

 

[Masterd]

Clogged cat?

 

[mikeinri]

Ditto on the codes. If it's fuel management (other than a filter), you could have a bad sensor or electical circuit. I had a similar problem, with black soot, turned out to be the MAF sensor, as well as the O2 sensors.

While plugs and wires are always a good idea, at this point, it might be less expensive (overall) for you to get a professional diagnosis. Ask them to tell you exactly what is wrong (and why), and then you can decide if you want to fix it yourself or let them do the work.

Oh, and regardless of which way you go, use Ford parts for any sensors. Yes, I learned that the hard way.

Hope this helps.

Mike

 

[94Jo]

Turned out to be a sparkplug, the first one I went to change was "gunked" up so there was no gap left. So my engine was half-assedly running on 5 cylinders. I only got around to changing two before it got too late, will finish the rest tomorrow, but man it runs soooo much better already.

 

[Blacksheep Josh]

That'll do it. Mine was the same way, was spittin and sputtering all day long, sounded horrible. I changed one plug out, and man oh man! did it drive and feel different.

Keep on top of it, I change mine out about once a year, gives me something to do and it's not to expensive. You might also want to invest in a new set of spark plug wires as well. Just remember to replace one at a time.