More gas mileage

[Birdman_7]

Okay so I had a full diag done on my car, and this is what I was told:
No DTC set, and fuel trim set very high at 23%. Further inspection revealed split second tuning module piggy backed with pcm wiring.
Also,
No stock catalytic converter, or hollowed out cat. Exhaust is straight pipe with what appears to be a cat-back system.

Now, I was informed that I cannot pull the chip off without knowing if the injectors are stock, so I still have to figure out if they are or not.

They gave me quotes for the exhaust replacement, including OEM cat and exhaust manifold, and the price was outrageous. Then the guy found some stuff on ebay that would bolt on to my aftermarket callaway manifold, but this is all still really expensive... And the guy sounded really confident that this whole exhaust thing with reintroducing the catalytic converter to the car would make a dent in the gas mileage, how much he would not say. I would've thought that getting a catalytic converter put back on the car would NOT make a huge difference in gas mileage..

My question, I guess, is this: Should I worry more about getting the chip pulled, or the exhaust replaced, and which will have the biggest impact on the gas mileage? Or should I even bother and just deal with the 12 mpg?

Another question would be am I going to lose most of my power if I get rid of the chip?

Many thanks for help!

 

[mspwyatt]

If you get your car tuned you will get more. I'm running the same setup and get 30 highway

 

[powderider87]

The exhaust isnt the problem, and i would not think the split second is either unless it got messed up along the lines and is set waaaay too rich.

 

[tweety2300]

12 mpg? The chip is there mostly to lean out the overly rich stock tune which would result in better mileage. I would go to a mechanic that specializes in imports and tuning. Isn't Calloway the stock manifold?

 

[jdwk]

The SSAFC sends a low voltage (actually still some question about this) in closed to loop to trick the PCM into adding fuel. It adds fuel in 1% increments about once a second. This is the short term fuel trim. It takes roughly one minute of driving in a particular rev and maf value range for that fuel trim to become a long term fuel trim, so it can take a long while for long term fuel trims to creep up and carry into the open loop. 23% is pretty much that max. I thought mine went to 25, but it's possible your car just hasn't reached 25 yet or has possibly stabilized.

This is why piggyback tunes go bad. The idea is to add or subtract fuel with the piggyback to stabilize the O2 reading so that the fuel trims are zero, but it's kind of like balancing a marble on a ball point pen using the D pad of a nintendo controller. The SSAFC is setup for our cars, but there are too many variables for them to be perfect out of the box.

You should be able to tell what kind of injectors the car has by loading the R4 software onto an windows xp or ealier laptop and connecte it to the SSAFC with a serial cable.

Another quick check is whether the injectors are pink or not since the most common upgrade is the 440cc wrx injectors.

Your best bet is to get a really good OBDII scan tool or a bluetooth module and an app for your phone like Torque, which is what I've been using, and install a wideband if you don't already have one, and tune it yourself to get those trims back to 0 and in-boost AFRs to an 11.5 range.

The manual for the SS AFC is pretty decent. I can e-mail you a copy if you can't find it.

 

[hornsfan10609]

There is something very wrong. Could be bad MAF, O2 sensors or stuck injector. The car should feel like something is wrong if you are getting 12mpg.

 

[Preferio]

12mpg?!?! I thought I was getting horrible fuel economy at 19mpg! I stay in boost though, so that explains my horrible fuel mileage.

 

[f1yen]

Lol 12 mpg?!! I think i hit 14 or 15 when I got my WGA fixed, I boosed EVERYWHERE. I can squeak out 27 city if i granny it, have not had any long hwy trips to report on though.

Before that, a granny-ed hwy experience would only yield me 25mpg. But I found problems when I took the turbo assy out.
I would check to see the header is fully on the block, When I replaced the WGA, I found 2 loose bolts and 1 missing! it was leaking out like mad. This seems to be the increase in MPG for me.