Help me figure out whats going on here please....

I realize the 3.42's screwed me a bit, but this is insane.....10 tank fulls in a row 14-15MPG AVG, with 90% highway...WTF? Its a STOCK car, tried changing to tr55's from bosch plats, no change....

New fuel filter, plugs(tr55's), wires, opti, AC Delco front o2 sensors, CLEAN MAF, and always on 91.....you name it.....? What should I check next?

 

You need to get a datalogger on your car to see where the BLM's are at. Could be running rich.

-Tony

 

I just got my car and i used to get 14-15 mpg then one day i didnt put my foot into it as much as i used to and i got alot better gas mileage. But trust me it is work a few less mpg to actually "drive" your car!

 

only if u dont put many miles on ur lt1, when u gotta pay 2.36 a gallon for 93 octane down in south florida!!!!! i love my 2.73's and im always easy on throttle tryin to conserve fuel.

cory

p.s. most recent mpg calculation had me overall at about 21.7 Miles to the gallon. A little higher just on highway, but the 21.7 is overall, and that aint to bad.

 

I see that you !AIR system, did you remove your cat. If you didn't your cat might be getting clogged. Just a thought.

 

I agree with the clogged CAT suggestion. I had one clog up real bad and got 15 MPG. Changed the CAT and went to 26.2 on the freeway at 70 MPH.

 

just gut the cat....flow will be better and improve that gas mileage

 

Hmmm i never thought of the cats, but the problem with gutting is thats its a 96' dual cat car, which would suck to gut.... I think i'am going to order one of the stainless works - y pipes form summit, what do you guys think about those?

Does anyone know how ****ty an lt1 sounds like with stock cat back and no cats?

Also...
How did your car run when it was clogged up? My car seems to run fine.....slightly rough idle, and slight super small miss like 1100-2000, but pulls hard as ever........what symptoms did yours have?

 

u may want to look at ur EGR, could be dirty, disfunctional...or possibly like mine, and open all the time. Might be time to get rid of it if u dont have emissions.

Cory

 

My car threw a code...P0420 Catalyst system efficiency below threshold bank 1. Car actually ran pretty good but after the cat change I felt that the WOT response was much better, idle a bit smoother and the car actually sounded better. The code was the deciding factor for the needed cat change. I have the Actron OBD II autoscanner from Autozone. IT has saved me several time in diagnosing problems and being acurate in the pinpointing of the problem. Get one if you plan on keeping your car.

 

I Have a heavy foot, so I bought a vacuum gauge.... It helps me keep the vacuum at 18 Hg on the freeway..... Stock that is..

 

Does sound interesting on the CAT deal, i think i might just go ahead and get that ypipe. But i'd hate to get the ypipe and find out thats its the EGR, is there anyway to check the function of that? Like if i reach my had back there and manual push in that thing it moves reasonably free...how could i check it?

Does anyone know what these cars sound like with no cats and stock cat-back.?

 

I had the same issue but disappeared when I got a new high flow cat converter.

 

Damn, i would'nt know......When i had my computer re-programmed 6 or 7 months ago i had the back o2's deleted........

How many miles were on your car?

What issues did you have? exact same as mine? How many miles were on your car?

 

I had 88,000 miles on my car and i was only getting 190 miles on a full tank. After installing high flow cat and getting my car pcm tuned, I jumped up to 230 on a full tank. I think the high flow made a big difference. It was probably clogged.