Bad gas mileage

[gstjoker]

This car is starting to give me headaches and yet I still throw money onto it. Recently, after I installed my SAFC 2, cars been running kind of like chengsta in his thread "running rich or not enough fuel?" but not as bad. There's another problem with the car that I want to fix before all others for now is my gas mileage. It's been going down ever since I put in the safc 2, but the safc 2 is zeroed out so what's going on? I checked my spark plugs and they are only 1 month old and has black deposits on it so I guess I'm running too rich? The car is blowing out black smoke like crazy too!

I was reading around about what could be causing is it seems like mine is close to a bad front o2 sensor but I want to double check with you guys. Can the safc 2 read the volts on the o2 sensor? If it can, here's what mine read:

In-1: 0.020 v, In-2: .0965 v, thrt: 0.745 v, knk: 0.740 v

I also have the 2g data logger but I'm clueless as to how to read it. I currently can only use the ob2 guage program and for the o2 sensor, it reads some weird number cause it doesn't look like it's reading the voltage.

Please help me figure this out as I don't like driving 10 mpg or less. I want my 25 to 30 mpg back. Some dynotuning is in the future of course but first I want to fix this damn gas problem.

The car is a 2g gst, e3 16g, Greddy 24r fmic, afpr set at 43 psi, NGK BPR7ES spark plugs and wires, K&N air filter, gm maft blow thru, stock injectors and fuel pump, full 3" no cat. exhaust, and currently use 2g datalogger and the safc 2.

[bluntedelvis]

Could be vavle seals and valves for the black smoke, what are you running for boost? And if high boost might want to think about upgrading your injectors to 680's & H.p winebro 255 fuel pump. Also boost leaks can cause bad gas mileage.

[gstjoker]

I'm boosting 15 psi, and yes, I do plan on upgrading the injectors to 650/680 and a 255 fuel pump.

[bluntedelvis]

I think dyno tunning and some fuel mods will correct your gas issue.

[DSM_421]

This probably isn't the answer, but make sure your gas tank isn't leaking.

I've seen 1gs going around corners and a trail of gas comes out behind them.

[b00stcreep21]

Did you set the fuel pressure regulator with the vaccum line disconnected? If you say it happend after you put the afc in, and it's just zero'd out, unplug the afc and see if it gets better. If it doesn't, you either fucked up your afc wiring REALLY badly, or the problem is elsewhere

[gstjoker]

Originally Posted by b00stcreep21

Did you set the fuel pressure regulator with the vaccum line disconnected? If you say it happend after you put the afc in, and it's just zero'd out, unplug the afc and see if it gets better. If it doesn't, you either fucked up your afc wiring REALLY badly, or the problem is elsewhere

I did set the fuel pressure when the vaccum line was off. I'll try unplugging the afc tomorrow when I don't have work and see if it get's any better.

[DSM_421]

I wouldn't even drive a modified dsm without having it dyno tuned. You can get away with it, but just better to be safe than sorry.

[bluntedelvis]

A wise man told me "you can have all the bolt-on's in the world, it don't mean shit if it isnt tuned"..
By Josh at Lse..