2003 Alero 2.2l - Using More Fuel

[pappyl]

Have a 2003 Sedan, with 2.2l

Usually get 280-300 km by half tank (for a number of years now).
Recently though, mileage been worse (250 or less).

Problem started about 4 weeks ago.... 3 weeks ago replaced my cat after a rust hole emerged.
I replaced the O2 sensor - just in case.
I cleaned the Throttlle body, fund a gunky IAC piston in the process.
Ran FI cleaner through the tank.
No visible fuel leaks or odor.
No vacuum leaks.
Tightened intake bolts just in case.

Engine runs good, pickup good, idle even.

On the scanner:
ST trim jumps around a bit but avgs +5
LT trim - see up to +13.
Temp good.
Fuel closed loop.

If someone new was driving it, would not know there was a problem. BUT I know....

So what the heck have I missed?

Does anyone have some ST/LT trim comparisons?

Thanks

[pappyl]

Well since NO ONE replied on this...

Problem solved.
Should have caught it - the timing chain rattle noise.
I think she may have skipped a tooth already and the computer was doing its best to manage the timing. Alas the poorer fuel mileage.

315,000km and engine is toast.
Chain skipped again on starting and valves bent.

Putting in yard engine with 143km. Back on the road shortly.

New engine cheaper than my recent catalytic! (course I am doing this myself)

[Bahlzeron]

That was a baffling one.. probably why nobody replied, I sure was stumped. Might be a good idea to do a timing set (chain, gears, tensioner, guides, etc.) to the new engine before you drop it in, as with the engine out it will be far easier of a job to do.

[sleepyalero]

Thanks for the update.

I agree above.

[kbubb91]

i couldnt make heads or tails of the numbers you put up top

when i have to add gas to my car i usually ran about 220 miles, by that point its a hair below a quarter. long story short i usually get about 26-28MPG.

PS- my cruise control stopped working so i cant use that to save gas. if anything i notice i keep hitting 80MPH on accident. also i sit in stop and go traffic often, albany...smh