Sudden and considerable drop in MPG

[1jfuddle]

The car is actually my father's. It is an 01 Camaro. He drives his car basically for mileage (he is 71, so I guess I understand) and has always gotten nearly 29 around town. A little while ago his mileage dropped to around 23 with the same driving conditions. I have been stumped by this for some time now and I don't know where to look at his point. I have autotap and can use that if it helps. I simply cannot explain a 6mpg drop. He claims to feel no loss of power. What could be doing this?

Things we have tried(in vain):
New air filter
New fuel filter (was REALLY dirty inside)
Fuel injector cleaner with last 3 tanks


Any help would be appreciated.

[Fredless]

o2 sensors.

[firebird4u99]

spark plugs and wires.

[00firebird]

have it scanned at autozone, i think that would tell you if the 02 sensors,spark plugs, wires, etc.. are bad

[Turbo V6 Camaro]

PCV PCV PCV !!!!!!!!!!!!!!!!!!!

give it full tune up.

also your cat could be goign out, not uncommon for our cars.

new plugs will help alot too

[FlamespikeMST1]

Im with him, pcv.
hit the cat a few times if you hear garbage floating around in there, then its time to change it out for a new one.

[Darigaaz]

My firebird was getting 8 mpg and I know that it's no enzo so I had it looked at. Replaced four fuel injectors and it fixed that problem plus gave me a small performance boost :-D

[l1tech]

29 mpg around town, you sure he ain't drivin a honda?? Forget the spark plugs and wires unless the car is misfiring due to a bad one. Oxygen sensors are the first thing to look at when there is a sudden drop in fuel economy. What you really need to look at is the fuel trims and see if the numbers are way positive or way negative, this will give you an idea of where to look...is it getting to much fuel or not enough. In my opinion if he's getting 23 mpg around town he is making alot of people here jealous including myself

[shock_core]

In my opinion if he's getting 23 mpg around town he is making alot of people here jealous including myself [/QB]

x2

[FireFighter]

Originally posted by 00firebird:
have it scanned at autozone, i think that would tell you if the 02 sensors,spark plugs, wires, etc.. are bad

That would only work if the ses light is on.

[BLLDOGG]

Originally posted by shock_core:
</font><blockquote>quote:</font><hr /> In my opinion if he's getting 23 mpg around town he is making alot of people here jealous including myself

x2 [/QB]</font>[/QUOTE]i would be pissed if i got that bad of gas mileage [img]tongue.gif[/img]

[1jfuddle]

He is 71 and drives like it. There is some (although not much) freeway driving involved.
I am sorry for those who are "lucky" to get 23. I am making 475hp off of the juice with my LS1 TA and I get 22 around town and 30 on the freeway. It is an auto with a moderate stall converter.