my 98 explorer 4.0 sohc had been idling really rough. changed spark plugs and wires didn't help. today i noticed it smelled very hot but not the motor it was the exhaust then i found the egr valve positioning sensor (which has two small hoses on it) had been basically melted on the outgoing hose. Someone mentioned the catalytic converter may be clogged up causing a lot of heat and back pressure. has anyone had this problem or know if this sounds like it could be the problem

 

Isn't the check engine light on? sound like its running rich.

 

well at first it didn't but i finally got one and the code was a po175 (system too rich right bank) i have tried several things since then but nothing helped, i also cleared the code and it hasn't come back again. i did go and have the back pressure checked on the catalytic converters today but they were fine. can somebody please help me

 

Does the engine run fine at higher RPMs? If you have a scan tool you can check the o2 sensor voltage, make sure it move inbetween .1v and .9v. Also check the pulsewidth of the injectors. Have you check the EGR valve if its open slittly causing the rough idleing?

 

There's information on the web that indicates that the code P0175 is usually due to a problem with either the oxygen sensor on that bank or the mass air flow sensor. You might want to clean the MAF, particularly if you use any air filter that requires the addition of oil.