How would I tell if my catalytic converter is plugged? The reason I ask is that my one way commute is only about 3.5 miles so the truck never gets a chance to warm up much, and short commutes are the most damaging to an engine. Recently I have noticed low mileage (~12mpg). I had the plugs, plug wires and fuel filter changed. I have heard that plugged catalytic converters will cause poor mileage and poor performance. One thing I did notice when I was replacing my plug wires awhile ago was that one of the egr ports on the throttle body was plugged, I cleaned it out and re-installed it, not sure why or how it would plug.
Please help, $2.57 gas is getting really old especially when I am getting ~12 mpg.

 

How many miles on you truck?

Did you used to get good mileage and now you're getting only 12 mpg?

If I only drove 3.5 miles back and forth to work I would be suprised if I got as good as 12 mpg. Driving back and forth 20 miles mostly highway, plus everyday errands etc. I have been getting 13.5-14.5 mpg.

 

If the mileage is what you alway got then there's not much to do about it.
4 miles is hardly enough time for the oil to even thin out or the trans to come up to operating temp. So it's more than just the engine.
Your state make you use oxygenated gas and pay more for it because of the state mandate.
These fuel formulations cause higher consumption with the thought that cleaner emissions result.
Your truck monitors cat efficiency with two sensors each bank an should set a Cel lamp if there is a problem.
If you still want to do a test then ports have to be installed in each pipe ahead of the first cats for back pressure testing. Temp. sometimes is use to judge but you can't really know unless the pressure test is made or replacment is done, then you just blow a lot of money that you would buy gas with.
I know this may be insulting to some and I don't mean it that way, but CA. makes it hard for their people on many things and costs 'you' for being being put upon to excess.
The real way to get some relief is a small car or cycle for that distance.
That's what they are trying to force all to do, anyway.
Good luck.

 

Your mileage isnt going to get any better with short trips like that. It takes me about 5 minutes to get to school every day and Im getting 11 or 12 MPG. Short distance driving can really kill gas mileage.
When I drive back to Dallas (pretty much all highway), I get close to 15 or 16 MPG.

 

My truck has 70,000 miles on it. On a trip from LA to Mammoth last weekend I got 13 to 14 mpg all highway averaging 70 to 75 to whole way. Previously I had gotten around 17mpg at the same speed. In town I was averaging ~15mpg. So dropping from 15 to 12 is a 20% drop.
I have thought of buying an enduro or such as a commuter bike, but so far I haven't been able to find one that is actually reasonably priced. Compact cars blow and I know I pay for driving my truck in CA (CA charges a weight tax on trucks in addition to all their other BS) I would just like to make sure my truck is running at its best b/c decent power and decent mileage are always nice to have.

 

I'd move.

 

Since we're on the topic of cats, I removed 2 of mine because one of them was blown open. I have a 97 w/5.4. I replaced them with a strait pipe, and have not had any problems. yet. Is this safe for my truck? Or is it gonna cause me A/F problems?