It's been awhile since I posted about the problems I was having with my '94 Ranger. The truck was getting bad fuel mileage, idle was eractic, and the truck would from time to time bog down and lose power. I posted here as well as othe Ranger forums trying to figure out the problem. I read A LOT of posts searching for a clue. I had just bought the truck, so I knew little of its past.

At first it was hardly noticeable, then got worse exponentionaly. The first things I did:

Replaced the fuel filter, air filter, PCV, and cleaned the MAF and IAC. These were basic maintenance items, so they would had to have been done anyway. I also replaced the belt tensioner and belt because both were bad.

The truck would not warm up, so I replaced the thermostat which was stuck open. Then I checked all the vacuum lines and replaced the plugs and wires. All parts were motorcraft. There was no change in the symtoms, CEL did not work.

Then I needed a new clutch, so I had a mechanic friend change that for me while I pulled off the intake. The VC gaskets were puking pretty good so I replaced them and the upper and lower intake gaskets and put on a new CTS since it was already torn apart. Also at this time I checked the TPS with a multimeter and found it was faulty near the WOT position, replaced it. We checked the fuel pressure and found it to be within spec.

Then checked for any codes. Got a code for the EGR flow being insufficent and a O2 sensor reading lean, tested the DPFE sensor. Voltage was off, so I replaced thatand BOTH codes went away. It ran well for about a week, then the problem returned with a vengence. However, during this week I would frequently put the vacuum hose back on the REF side of the DPFE sensor, it kept coming off.

I took it to another mechanic and had him test the entire truck out. He called me and told me that the DPFE sensor was bad and that he was getting greater than 3 lbs of back pressure @ 35mph on a test drive. He said at one point the engine blew off the fitting for his pressure gauge. I told him that I had just replaced the DPFE sensor and that the vacuum line kept coming off.

That is when he said that he was almost 100% sure the cat was faulty. Probably a piece had broken loose inside and was blocking the flow of the exhaust until I stomped on the gas. It would also cause the DPFE sensor to go bad.

I week later I replaced the cat, both O2 sensors (it was obvious they had seen many miles), DPFE sensor, and put on a Magnaflow muffler. Since then the truck has run better than ever and I picked up ~5mpg on my daily commute. I also fixed the CEL (light bulb blown).

Just thought I would share what I had done to my truck and how the problem was finally solved. I was quite aggravating at times.

 

Hi 77300i6,

Just to concur: A most definate back-pressure problem you had!

And it's worth mentioning time over that it's the feed back, from the many here @ FTE is what keeps her running...hopefully forever!!