I'm just wondering what everyone else with a FI 2.8/auto gets for milage, I get about 14-17 consistantly, and that sucks. My 84 z28 with a 350 and 4.11s will get 19 all day long.

to correct the problem (and for fun) I have done:
full tuneup including new wires
repaied exhaust leaks
home made cai
cat delete
AFPR - 46psi
timing 12 deg
patched up any vacuum leaks
replaced maf

I also get intermittent codes
34 - maf circuit voltage low
44 - exhaust system lean

weird how I'm pretty sure I am severely richening below 3K RPM
I had a scanner on it and it was showing like 65 points rich at idle.
And it likes to try to stall at lights, but it's a weird stall. Makes a funny noise and seems like it just dumps gas in for a second and almost stalls then throws a code 34.

it's pretty and I just want it to run good!

any ideas would be great, thanks.

 

Sounds to me like a new MAF and O2 sensor are in order....

Also, turn your AFPR down to about 42psi...

 

Just noticed you replaced the MAF... was it one for a V8 or V6? They were different, if I recall correctly...

 

Forgot to mention, have a recent o2 sensor as well
and 42psi is stock
yes, replaced the maf with a brand new GM replacement.

yes the v6 and v8 mafs are different:
v6 maf = 3 wire hot film style made by ac delco
v8 maf = 5 wire hot wire style made by bosch

 

Very odd... with everything having been replaced, I'd recommend running a data scan while the engine is running, and work from there.

Have you checked to be sure you have 12v at the MAF?

 

Oh yeah, I know 42 is about stock... I'd recommend keeping it stock until you get the engine running smoothly, then change the fp and such...

 

I think i'm going to try running down the flowchart on those codes again.
I wish my car was OBD II
freeze frame is awesome
I'm pretty sure it'sa fuel trim problem
put the computer in backup spark and fuel and it runs great...
I hate problems that can't be solved with a wrench

 

LOL, I know what you mean... but if you want to work on 'em, you just gotta grit your teeth, and figure it out.

Imagine in a couple years, they might be going 'Man, I hate problems I can fix using electronics' What will they be then?

 

I had a thought, how about a really slacked timing chain. It seems to randomly lose vacuum so maybe it's just bangin around the cam at idle? then I take off and it acts better...

sound possible?

I checked the maf and all the wiring and it seems fine.
I can't see the computer just randomly doin all of this...

I'm desperate to figure this out... if you can't tell.