00 Explorer Limited 5.0 possible Cat problem?

[smcmoran]

I am stumped and need opinions - I think I have clogged cat(s) but not sure.

I have a 2000 explorer 5.0 with 192k. for some time it seemed like it was starving for fuel at high RPM and I started getting diagnostic codes. Started with the p0174 and later p0171. I checked the normal things for leaks, replaced the fuel and air filters, MAF and the IAC. there was always a telltail harmonic hum the air intake at cold low idle. Still ran pretty good, until the other day while backing into a driveway, I went over the curb(had too) pretty hard. When leaving, it didn't want to start easily. Sounded flooded and missing but I revved it and cleared it out. When we started driving, it had no acceleration past half throttle. seemed to idle pretty good but couldn't push the pedal too hard or it would fall on its face.

Double checked for vacuum leaks and finally decided to replace the upper intake gaskets. While off I either broke or it was broken, the PCV T under the manifold plenum. Gaskets looked good, but replaced them, cleaned everything back up, installed all new rubber hoses under the manifiold and reassembled.

Still falls on its face when I punch it, It also is very hard to start. Its trying and barely catches and then you have to rev it an clear it to get it to idle. Once you do, it idles great.

So should my next step be cat's and if so where to start since there are 4 or fuel pressure? My wife loves her truck and I really want to keep it going for her so any help is appreciated.

thanks all!!

 

[my98nnj]

When the cats start to fail they usually allow the truck to run ok cold, then as things heat up you lose power when you get into the gas. Is that what's happening?
You can see poor air flow through the motor if you watch the MAF sensor readings with a scanner, that should help diagnose clogged cats.

 

[SoHK_alumni]

There are test ports available to install a pressure gauge in the O2 bungs. Makes it easy to check for excessive back pressure.

I made one using a spark plug non-fouling adapter but test kits ars commonly available.

 

[smcmoran]

Thanks for the input all.

So its not running well cold and getting worse at it heats up. If anything, its somewhat the opposite. Its very hard to start(doesn't want to catch) when cold but starts better when its warm and the acceleration is about the same in both cases.

I like the idea of the back pressure gauges but its impossible to get to three of the four O2 sensor bungs. I'm wondering if I can get to them from up top, beneath the console.

Any other thoughts?

 

[istroo]

Fuel pump

Check your fuel pressure, the port is under the plastic throttle body/accel cable shield at the fuel rail. I would definitely check that before messing with the cats.

 

[Turdle]

Thanks for the input all.

So its not running well cold and getting worse at it heats up. If anything, its somewhat the opposite. Its very hard to start(doesn't want to catch) when cold but starts better when its warm and the acceleration is about the same in both cases.

I like the idea of the back pressure gauges but its impossible to get to three of the four O2 sensor bungs. I'm wondering if I can get to them from up top, beneath the console.

Any other thoughts?

Well, I can help with removal of the console

http://www.explorerforum.com/forums/showthread.php?t=209770&highlight=remove+center+console

It might not hurt to check the cats out just for elimination. Let us know what you find please!

Does the check engine light illuminate and then go out once the engine is running or does it stay on?

My head cannot get away from the bump while backing. I feel something let loose--

 

[smcmoran]

The light only goes out when I erase the codes....and it comes back pretty quick. Usually after idling and staring a couple of times, Teh freeze frame shows that the lean condition is with RPM's below 600 and the vehicle speed at 0 so I am assuming its when I'm starting.

I'll try and get a good connection on the pressure valve and see what I get. Anyone have clues to the standard pressure with key on, starting and idle?

Turdle, Thanks for the console info and I will check the Catsd after the fuel pressure. I have a fuel pressure guage set so it might be easier for that check first.....

I'll keep you all informed

 

[Turdle]

Oh, lean codes?

Check the PCV valve grommet and line.

Also--sometimes the vacuum assist brake booster will leak internally. Unless the fuel pressure is very weak, you have a vacuum leak somewhere. were the codes p0171 and p0174 still coming up?

Any other displayed codes will help to troubleshoot this.

 

[smcmoran]

yup, the infamous p0171 and p0174. Still come up after replacing the PCV valve, all the hoses and the grommet(for the heck of it), I did not pull a test on the vacuum booster, other than letting it sit for a couple hours and then pulling the check valve - still had vacuum in it.

Seems like I've been over it top to bottom and the codes don't change....lean both banks

 

[smcmoran]

For the record, it was a weak electric fuel pump. dropped tank, new pump, runs great and no more code

 

[XLTrunner]

I think I speak for most on here when I say "thanks" for updating us with your solution. Any and all information regarding the resolution of a problem is bound to be of help to the next owner who encounters similar problems. Glad you fixed the problem.