Mechanic says its not a transmission issue...

[Dalmus]

I originally posted this as a transmission problem, but after checking it out, my mechanic friend is 99.99% positive its not a transmission issue.

Here's the issue:

On Friday, everything was normal. On Saturday, I hooked up a boat and trailer (under 2,000 lbs total) and headed up north. I found that I wasn't able to maintain 65 mph on average inclines on the highway, something I've never had problems with before. I turned around, dropped the trailer at home, figuring between the slightly heavier load than normal and the strong headwind, I just hit a wall with the ol' girl.
Much to my distress, I found that I had the exact same lack of power even with NO load. Through more careful observation, I found that under 2,500 RPMs, I seemed to have normal power. As the RPMS go above that point, the power goes down.
There are no unusual engine sounds... No stuttering or missing, no bogging. The gears shift normally on the way up as long as I don't exceed 2,500 RPMS. The engine downshifts as normal at highway speeds when I press the gas pedal (to attempt to pass another vehicle, for example), and there is no revving up the engine.
No check engine light, no blinking O/D light.

I checked the air filter, its fine.
I disconnected the battery and let it sit for 2 hours to force the computers to reboots... No change.

My mechanic buddy:
Checked the fuel pressure... its normal.
Checked and cleaned the MAF sensor... no change.
Ran a test with the ODB II computer that said one of the rear O2 sensors was getting unusual readings that might indicate a problem with one of the cats, but there is no indication of exhaust backflow from a bad cat to explain the loss of power.

He's going to talk to another of his mechanic buddies that used to work for Ford, but for now he's stumped.

I DO have either a bad rear ABS sensor (or possibly just the VSS) that, from what I've seen here, can cause a whole host of seemingly unrelated problems, but he insists that it shouldn't be related to power issues.

Has anyone else encountered anything like this? Any ideas of the next thing to check?

 

[mr2fix2it]

sounds like a clogged catalitic converter you can check by dropping y pipes at engine and driving except for the noise it should have power back or get an exhaust back pressure gauge and check at front o2 sensor anything over 2 pounds of pressure under a load is bad.Its easier to drop pipes.

 

[rileyrs]

check for a clogged cat first, move on from there if that isnt it.

 

[Dalmus]

He did suggest dropping the pipes and driving it that way, but he said he'd need the car for several hours for the system to cool down enough to have reasonable chance of not breaking the bolts. I'll suggest doing that this weekend.

So, just casually pricing stuff out on different auto part sites, I've found myself a bit confused (I'm a wiring and sensors guy, not a hardware guy!)... There seem to be two very different styles that NAPA and Advanced Auto say are for my vehicle. As a reference, Advance Auto part numbers 53500 and 50545 that have the exact same description. Why the two difference systems for the same vehicle?

 

[Dalmus]

sounds like a clogged catalitic converter you can check by dropping y pipes at engine and driving except for the noise it should have power back or get an exhaust back pressure gauge and check at front o2 sensor anything over 2 pounds of pressure under a load is bad.Its easier to drop pipes.

After talking with some mechanic friends of his, he agrees with the clogged cat theory...and guestimates $1,500 - $2,000 to replace all three cats. Ouch! He said that with the age of the vehicle, he recommends using Ford parts (why would that be?).

Is there any chance that the O2 sensor could be the culprit? $60 for an O2 sensor (I can replace that myself) is sure a lot better than $2,000.

If not, is there any reason I can't insist to just cut out the bad cat (I assume it would be the cat directly in front of the O2 sensor with the unusual reading) and weld in a universal? Or does the Y-piping pretty much force me to at least replace the the back two cats?

 

[bamnq6]

What kind of emission testing does Wisconsin do??

I'd check and see if magnflow makes direct bolt-in for your truck. I can't believe that it's 2000 for ford parts... OYE!

Also, what's your mileage? If you're under 100k, ford may havta replace the cats (not 100% sure on that thou)

 

[Dalmus]

What kind of emission testing does Wisconsin do??

I'd check and see if magnflow makes direct bolt-in for your truck. I can't believe that it's 2000 for ford parts... OYE!

Also, what's your mileage? If you're under 100k, ford may havta replace the cats (not 100% sure on that thou)

Wisconsin basically just plugs into the ODB II port and runs the computer test to see if any faults are reported. They don't physically sniff the exhaust anymore.

Unfortunately, I'm at 117K... otherwise I'd be covered by the federal 7 year/100K warranty, I think.

Looks like Magnaflow does sell the front half and the back half of the cat system seperately. Since its only the left bank O2 sensor that's throwing the trouble, might I get away with only replacing the rear section?

 

[Dalmus]

Update...

Ford wants $1,800 for the Y-pipe system. Mechanic said he could get an aftermarket for $1,200.

He told me he'd be happy to install something I find myself, as long as I understand that I would have to deal with whoever else for hardware warranty issues...

So I found the entire Y-pipe at discountconverter.com for $479.00 shipped... They say all their parts are new, and covered by the 5 year/50,000 warranty.

I assume I should replace the O2 sensor that reported the fault, too, just to be sure I don't toast my new converter?

 

[bamnq6]

If you've never replace any of them, I'd replace the whole shebang.

When I replace the whole lot on my former Merc, I picked up 2 mpg (18 to 20).

 

[Explorer Junky]

After talking with some mechanic friends of his, he agrees with the clogged cat theory...and guestimates $1,500 - $2,000 to replace all three cats. Ouch! He said that with the age of the vehicle, he recommends using Ford parts (why would that be?).

Is there any chance that the O2 sensor could be the culprit? $60 for an O2 sensor (I can replace that myself) is sure a lot better than $2,000.

If not, is there any reason I can't insist to just cut out the bad cat (I assume it would be the cat directly in front of the O2 sensor with the unusual reading) and weld in a universal? Or does the Y-piping pretty much force me to at least replace the the back two cats?

He maybe a friend, but, I would just go to Summits
website and order universal replacements. Even there direct fit ones will be cheaper than that!
http://www.summitracing.com/parts/M...ear|1994|Make|FORD|Model|EXPLORER&prefilter=1
1500-2000 !! WOW you could almost rebuild your engine for that!

 

[03silversvt]

My brothers old dodge ram had the same problem with his cats. We removed them from the truck and gutted them. Ram them with a steel bar or something till it all falls out. Guess what, the truck passed emissions too. Exhaust note was a tiny bit deeper but nothing really too noticeable as he still had stock muffler. Just some food for thought and wont cost u a dime but your time

 

[Dalmus]

He maybe a friend, but, I would just go to Summits
website and order universal replacements. Even there direct fit ones will be cheaper than that!
http://www.summitracing.com/parts/M...ear|1994|Make|FORD|Model|EXPLORER&prefilter=1
1500-2000 !! WOW you could almost rebuild your engine for that!

The O2 sensor that failed was pre-cat, I would think it would be more likely that the bank 1 cat would be bad... and if I have to spend $350 for the front half of the assembly (2 cats), I might as well spend $100 more and replace all three right away.

I would love to just pull them off and ram them clear like 03silversvt suggested... I don't know if I would have the luck to pass emissions after that though. Wouldn't the rear O2 sensors tattle?

 

[onetimer13541]

Wow. Those prices are crazy. I was out trying to find a vacuum leak on my newly acquired 5.0 liter Explorer. I revved it up a few times smelled some smoke. Took a look under the engine and saw the cat on fire. looks like it has a minor rear main seal leak that's dripping on the converter and that vacuum leak is probably from the clogged converter. first time I've ever seen that. Its a shame because the engine and trans seem to run good. but in my experience breaking out the insides of a catalytic converter is the best performance upgrade you can get for cheap. And as far as i know they quit testing emissions in my state. Good luck with yours. Mine i think is on its way to the junkyard. now I know why I'm a Chevy guy