4.0 with no power

[mmoenter]

Here's my dilema...I have a 96 Ranger STX 4x4 with a 4.0 automatic. Mileage is around 140k. When I first got it, I was averaging about 18mpg on the highway. A while back I went through and did a tune up to it (Autolite plugs double plat, duralast wires), oil change (Fram filter I believe), and new air filter. Shortly after this (not right away) I noticed my fuel economy was garbage (16 highway MAYBE, 13 city if I'm lucky). At that same time I noticed my 4wd was acting up so we fixed that problem but the economy was still garbage. It also seems like there's really no "grunt" to the truck...whether it be around the city or getting on it on the highway. We also gutted the cats thinking that would solve something but it didn't. I had our mechanics at work pull the codes and there was one for the canister purge valve and one for the o2 sensor. I changed the valve and unplugged the o2 sensor with no positive results. Lately I acquired an old 15' fiberglass boat and when backing it in our driveway I had to give it almost 100% throttle to get the boat to start up our driveway. I does seem to have a small miss when its idling. I had the mechanic check fuel pressure and I don't recall what he said it was but he said it was within normal range. It's been squeaking lately which at first I thought was maybe the belt but seems to be coming from the back of the engine (cam position synch.?). I'm pulling my hair out trying to figure this thing out and I need to get it in better shape before spring since we've already upgraded to a much newer 18' boat. Thanks and sorry for the long story!

 

[Earl43P]

"mechanics at work pull the codes and there was one for the canister purge valve and one for the o2 sensor. I changed the valve and unplugged the o2 sensor with no positive results."


I'd have to say replace that upstream O2 sensor. They have a dramatic effect on fuel mileage, engine efficiency and POWER. You need new mechanics.


Welcome to The Ranger Station.

 

[Big Jim M]

Welcome Moe Have you put new tires on that truck? What size are you running? Change out the 02 as said above.
Big JIm

 

[Ranger44]

The plugs gapped correctly? With feeler gauges.

I'd replace ALL the O2 sensors. If one is going, their all bound to be going soon.

Also, that EVAP system is finicky and problematic. Keep an eye on that.

 

[Tony Raine]

your truck will run like crap with a gutted cat. the o2 sensors are picking up a problem with the cat (its not there), and maybe throwing the truck into limp mode.

get a universal cat welded in (cheaper than direct replacement), and that should help

 

[Ranger44]

That will happen on a 96'. That 3rd HO2S watches the efficiency of the catalytic converter. Your gonna get all kinds of stuff happening.