update on CAT

[Jimmy F]

Morniing all.. This is a follow-up to what I was told to do about the MPG issue I have been having..



Looking for the experts advice on this one:



I hooked up the pressure gauge and he is what happens:



Idle = about 18 or so

lite excel = 10-12 or so

heavy excel = 5 or so



Are these signs of the CAT going bad??



The fuel filter was changed over this past summer.. not really sure what else could be causing the 10 MPG that I have been averaging the last couple weeks.. (outside of the winter issues)



Thanks in advance,



Jimmy

 

[Fred]

Jimmy,



You said lite excel and heavy excel. Does this mean you were watching the guage while you were driving?



Just to clarify: All this is done while standing by the truck with the hood up. You'd connect the vac gauge to the big vac line that connects to the brake booster. Observe vac @ idle. Then rev the engine to ~2500 RPM and just hold it there steady for 5 or 6 seconds. Right when you first rev the engine, the vac WILL drop, but should return to fairly close to where it was @ idle. If the vac stays closer to the value it was when you first revved the engine, instead of returning to fairly close to where it was @ idle, then I'd suspect a restriction of some type, possibly the CAT.



I hope this helps.

 

[Jimmy F]

Ok, while the gauge was hookup.. I used the throtle thing to slowly and fast excel the veh.. yes it was parked and on a lift to be exact.



Jimmy

 

[Fred]

If the vac stayed at the levels you said, while holding the RPM steady for a few seconds at each RPM, then I'd suspect a restriction.

 

[Jimmy F]

Ok.. I will have to recheck when I get home tonight.



Thanks Fred.



Jimmy