Checking for a clogged cat...

[kunar]

well after some recent engine troubles it has been brought to my attention that it may be a clogged cat causing the problems. i was told that a colgged cat will run hotter than normal, anybdoy have any idea of the temp range? i have an IR thermometer i will use tonight to test it after its hot. i have also read that your vacuum at the intake will be low, anybody know what the figures should be there? i'll check that tonight as well.

 

[85_Ranger4x4]

Here is a good site I found researching cats for F-150, it seems like a good site about them.

http://aa1car.com/library/converter.htm

 

[Wicked_Sludge]

temperature is NOT going to tell you anything. true that plugged cats usually run hotter...but temp. depends on too many other factors (like how long the motor has been idling, what speed you've been driving, how well your cooling system is running, how rich/lean your fuel system is, ect) to tell you anything useful.

vacuum is the way to go on this. at idle, you should get a reading of about 20". a plugged exhaust system will cause either a steady low read....or a reading that starts out normal, and slowly drops to low or zero.

unfortunately, there are also a few other things that can cause smiler readings. dont take any one result as 100% proof.

 

[kunar]

it doesnt appear to be a big issue. about 15" at idle and if i gas it a little, it drops then picks back up to about 20" and cat temp was less than 100* difference from inlet to outlet. i guess i will continue my explorations elsewhere...