I just bought a 00 Scab 4x4 4.6 auto. It has 93,000 on it but only 4,000 in the last year. I've got a feeling that the cats may be clogged. Idles fine but seems like it could have more power at the top end. Also seems to really hunt for the gear it's trying to find at the top end. Is there a definitive test to decide if the cats are bad? I had read about drilling holes and doing pressure drops but I don't have anyway to weld them up.
Thanks,
matt

 

A local muffler shop can do a backpressure test for you. I think it cost me $15 and about 20 minutes of my time when I had it done a while back.

 

Thanks for the reply! I'll get it in tomorrow and see what they say.

matt

 

Double post....love this laptop!

matt

 

haha, got any news to report now? my '01 at 83k cats are fine

 

Nothing concrete. I did find that the only way to test the cats positively is using a 5 gas analyzer. I called several places...most wanted between $60 and $80. I found one guy that would check it for $30 but is on vacation until after Halloween. I'm going to wait and have him do it.

Something funny...I called my local Ford dealer and asked them about checking it. They told me that they would take the truck for a test drive. Then take the exhaust off and take it for another test drive and see if there was a difference!! Talk about Seat-of-the-pants engineering!

I'll update this when I have them tested!!

 

i tested mine in 2nd gear from idle to 5400 rpms with a magnahelic gauge ran from in the cab to a fitting that went into the 02 sensor bung via tubing- where do you live?-phil

 

I live in Cincinnati, OH.

They may not be bad. Just feels like the power is restricted...especially at higher speeds (35-70mph). Feels to me like it should "open up" a little more. Most companies that I talked to didn't want to give me a price to analyze the problem only to switch out the cats!

 

You may want to check the baro function of your MAF.
A mechanic's scan tool can check it quickly.

Also, are you sure that the maintenance schedule was observed by the previous owner?
Things like old plugs, restrictive fuel and/or air filter can cause sluggishness.

If there are no codes, I suggest checking the simple stuff first before you start replacing things.
Throwing parts at a problem can get expensive.

Has your truck slowed down, or is it just slower than you think it should be?
A 4x4 SCAB is quite heavy, not really all that fast with a 5.4 let alone with a 4.6...

 

I don't know if the previous owner followed the recommended maintenance schedule (has 93k). That said, the truck is very clean. No runs, drips or anything underneath. I bought it about a month ago. After I bought it, I put in new plugs, air filter, fresh oil, filter, stuff like that. The other day I got a "slow response O2 sensor" code. It hasn't come back since Autozone cleared it. I'll be changing the fuel filter next. The truck hasn't really been driven over the last year.

Since I just got the truck, I can't tell if it's slowed down. What I notice mostly is that it seems to struggle to move through the higher gears for the tranny to shift. It shifts smoothly just really feels like it struggles to get there. Seems like the pedal has to pushed way down and the rpm's really get low before it downshifts at highway speeds. Could be a tranny thing but I don't think so.

matt

 

My F150 is the same, then it gets to the point where I have it floored then it roars to 5500 and speeds up quick, I think it just needs a tune, and the overdrive is what keeps it from speeding up at highway speeds, Fords overdrive is designed to always be on, the transmission has 4 gears, but when you feel that 5th drone down thats the overdrive working to save you fuel