Plugged Cat Converter?


robster1
08-27-2006, 04:21 PM
Hey there, I'm chasing a fuel consumption problem and I'm wondering if a plugged cat converter could be a culprit and how do I test for this? I own a 2000 Blazer 4X4, 95K's, I've replaced plugs/wires, O2 sensers(3), fuel filter,
air filter, brakes/all around, cleaned MAF sensor, flushed tranny/filter, fuel inj
cleaners, new tires(same size) 235/70/15. No lights, no codes just crappy fuel economy 500km/60 liters or about 18-19 mpg all highway. What other issues can arise from a plugged or partially plugged cat?

Eslhockey92g
08-27-2006, 06:31 PM
Thats doesnt seem to bad. I get about 15 mpg on the highway, thats also with 31's and 3" lift

billibong
08-27-2006, 07:02 PM
I average about that on mine, 18-20mpg on the highway. I think that sounds pretty good.

BlazerLT
08-27-2006, 08:20 PM
Yip, that is good.

Nothing to complain about there.

Which O2 sensors did you change?

If you want to help your ecomony, put a better flowing muffler on it.

The stock muffler is huge and really restrictive.

robster1
08-28-2006, 06:24 AM
I've changed all O2 sensors(3). My economy was previously much better,
around 21-22mpg (highway). Does a fuel system flush restore some performance?

Cloud Strife
08-28-2006, 10:23 AM
This may be dumb, but if you are running the Air Conditioner it may be hurting your MPG slightly.

534BC
08-28-2006, 10:46 AM
Hey there, I'm chasing a fuel consumption problem and I'm wondering if a plugged cat converter could be a culprit and how do I test for this? I own a 2000 Blazer 4X4, 95K's, I've replaced plugs/wires, O2 sensers(3), fuel filter,
air filter, brakes/all around, cleaned MAF sensor, flushed tranny/filter, fuel inj
cleaners, new tires(same size) 235/70/15. No lights, no codes just crappy fuel economy 500km/60 liters or about 18-19 mpg all highway. What other issues can arise from a plugged or partially plugged cat?

A plugged cat will rob power long before mpg , but anyways to check it without removing pipe a pressure gage can be hooked to exhaust system before the convertor. I used an old spark plug with the gutsd removed and adapted to a heavy duty hose and can screw it into the O2 sensor hole and use the gage inside the cab. Just a couple pounds is normal when running full rpm and wot, I have seen systems with plugged cat peg a 60 pound gage and these are the ones you can also hear the sound.

534BC
08-28-2006, 10:52 AM
I've changed all O2 sensors(3). My economy was previously much better,
around 21-22mpg (highway). Does a fuel system flush restore some performance?

You sound like you keep good tabs on your mpg, I agree 22 down to 19 is pretty drastic for no apparent reason. Mine gets 22-23 highway and 18 on city streets. The city mpg has come down 1 + mpg over the years. One thing I would do first is to verify the figure (you probably did already) :lol:

Check odometer calibration and gallons if possible, It may also just be a fluke and you happened to fill tank higher or made a mistake on figures also?

How many tanks did good on mpg and how many tanks did poor?

Did you change routes, speeds, drivers, ect.?

BlazerLT
08-28-2006, 12:45 PM
Also, did you recently change tires?

Add anything to the truck? Subwoofers and such? Hood or window deflectors?

Rick Norwood
08-28-2006, 09:56 PM
For what it is worth, I just dumped the big bottle (there are two sizes) of Techron fuel system cleaner into a full tank of gas. This was recommended to me by the mechanics at the dealership. GM sells a similar product for $30 USD. I bought this at Autozone for $10 USD. I'm sure Wal-mart sells it too, Probably cheaper.

If you look real close at the GM bottle, somewhere on the bottle or on the label, there is a chevron symbol.

Anyway, I went from 235 miles per tank (Approx. 20 gal tank) to 330 miles per tank. IN JUST ONE TANK FULL.

It is worth the $10 and won't hurt a thing. But be sure to use the Techron and look for the Chevron symbol.

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