urgent help needed 2004 running bad,won't rev or move.

[cjben]

Need the vehicle running before Monday if possible. It's a 2004 4wd 4.6 v8 with 140,000 miles. My wife was driving around town today and had to park it at her daughter's house because even if you floor it,the engine will only rev to about 1500-1800 rpm's and idles really low,maybe 600 rpm. she said right before it started running bad,there was a bad smell. Also there is a humming/rattling noise that sounds like it's coming from the upper intake/throttle body area. I went and looked at it,tried to pull codes. The check engine light isn't on and there are no codes stored in the computer. A couple of days ago,there was code po420 (Catalyst System Efficiency Below Threshold (Bank 1)and the check engine light was on. Engine was running fine. I cleared the code,and it never came back. I am not sure this is related,just trying to give all info possible. Thanks for any help!!

 

[Hugh Janus]

Need the vehicle running before Monday if possible. It's a 2004 4wd 4.6 v8 with 140,000 miles. My wife was driving around town today and had to park it at her daughter's house because even if you floor it,the engine will only rev to about 1500-1800 rpm's and idles really low,maybe 600 rpm. she said right before it started running bad,there was a bad smell. Also there is a humming/rattling noise that sounds like it's coming from the upper intake/throttle body area. I went and looked at it,tried to pull codes. The check engine light isn't on and there are no codes stored in the computer. A couple of days ago,there was code po420 (Catalyst System Efficiency Below Threshold (Bank 1)and the check engine light was on. Engine was running fine. I cleared the code,and it never came back. I am not sure this is related,just trying to give all info possible. Thanks for any help!!

Disconnect the negative terminal on the battery. Wait 30 seconds and reconnect. Your ECU went into limp mode because your cat died.

 

[cjben]

I did disconnect the negative terminal just out of curiosity. no change in the way it ran. I put my hand over the exhaust pipe when it was running,and the engine never pulled down or changed speed at all. Would this indicate a plugged cat? I guess what has me stumped is the noise it is making,the humming/rattling noise. Would that be from the exhaust gases trying to get out somewhere else because the cat is blocked?

 

[kryhavoc]

if your cat crumbled... pull a bank 2 (either one after the primary cat further from the engine) o2 sensor out (temporarily) and crank it again... if it runs better then you blew a cat up and plugged something downstream. Do not run it long this way, as you are ejecting exhaust under the body... not good for anything but a quick test to see if it helps. The humming in the intake is probably the EGR releasing excess pressure if the exhaust is blocked.

 

[cjben]

Is the o2 sensor the standard socket size? I have a socket if it is,but the vehicle isn't here for me to check

 

[kryhavoc]

7/8's wrench.. not a socket unless you have a special one that is split to let the wiring out.

 

[cjben]

Yes,I meant standard o2 sensor size. I do have the special one for o2 sensors,just didn't know if they made different sizes.

 

[Number Twelve]

Your ECU went into limp mode because your cat died.

The car commits suicide for a catalytic converter failure? Thanks. I did not know that.
I'm just glad Ford enforces a legal requirement on behalf of our government.

 

[dunner]

hey cjben,

Im kinda having the same issue. Does the engine idle like sh8t and bog down when you hit the accelerator? Ive changed numerous things and am starting to think its my CATS

 

[kryhavoc]

Mine did... the drivers side primary cat blew up.... the parts and pieces of it then clogged the secondary downstream cat. When i pulled a O2 sensor the motor ran 90% better which gave me the clue the exhaust was plugged. I removed the secondary cat by unbolting it and cleaned it liberally with water and compressed air... i reinstalled it and it works for now. Saving up the money to get another system.

This is what it looked like in front of the secondary cat.

 

[cjben]

hey cjben,

Im kinda having the same issue. Does the engine idle like sh8t and bog down when you hit the accelerator? Ive changed numerous things and am starting to think its my CATS

yes,it idles about 600 rpm and will not rev past 1800,not even close to being driveable unless you want to idle at about 2 mph

 

[imp]

The car commits suicide for a catalytic converter failure? Thanks. I did not know that.
I'm just glad Ford enforces a legal requirement on behalf of our government.

Hell, it's worse than that! Maybe you looked at my miserable mess about ABS, Module died, threw P2106, Forced Limited Power, then Forced Limited Idle! They're push the credibility limits! And, to date, I've found no way to defeat the G.D. ABS! imp

 

[cjben]

would a bad egr valve cause this?

 

[imp]

would a bad egr valve cause this?

I wish I knew what-all symptoms Ford included in allowing "Limp Mode". But, EGR valve "bad" means it is not opening and closing, stuck open or closed, and there is a movement sensor on it which sends Valve Position info to PCM, so, if valve fails to move when PCM tells it to, a DTC is thrown calling out EGR Valve Position Sensor. A Check Engine light would be the alert to look for codes. Possible that if the vehicle is driven a long time, say miles and miles, the PCM MIGHT be programmed to cause "limp mode". imp

 

[cjben]

that's what is so hard about figuring this out. No codes in the computer at all.

 

[imp]

Mine did... the drivers side primary cat blew up.... the parts and pieces of it then clogged the secondary downstream cat. When i pulled a O2 sensor the motor ran 90% better which gave me the clue the exhaust was plugged. I removed the secondary cat by unbolting it and cleaned it liberally with water and compressed air... i reinstalled it and it works for now. Saving up the money to get another system.

This is what it looked like in front of the secondary cat.

Not meaning to find fault, but mine (4.0L 2004 XLT) does not have an Upstream and Downstream cat. There is one cat for each bank of cylinders, and their outlets come together into the tailpipe. imp