BYFF

Now i am new here, but i've been here reading since I got my car, so I got most of this down.

so I picked up an 06 ss/sc a couple months ago, with a dealer installed gms2 kit.

I know the gms2 flash runs overly rich, but, I'm consistently getting 16-18 mpg, for about ten calculated tanks now. Not much difference whether I granny drive a tank, or WOT most of the next tank.
The car runs great for the most part, but is that low of mileage normal?

I was going to order a zzp kit in two weeks, and get it tuned, but I wanna make sure I'm not overlooking some type of problem.
No CEL, did all the basics, air filter, checked the cat, new plugs, a bg44 cleanout.

I know these things run rich to begin with, but 16-18 consistently?

Any insight on this would be appreciated, thanx. _chris

rickets112002

I averaged 23 mixed.

cranemaster

if its anything like my LNF, not a HUGE difference between a heavy foot and driving like a grandma.. but there would be over a long time obviously..

alleycat58

For just stage 2, that's a bit low. Do you have a wideband/have you logged it to see just how rich it's running?

ssyellow

Christ almighty how do you people drive haha.

I baby my car like none other, GMS2 and I get 29-32 mpgs. Try being REALLY easy on it for a tank and see what happens. Good luck.

Oh and reset your dic mpg thing to get a good reading.

MyOtherSS

iTrader: (1)

yeah that seems pretty low. I'm getting 24 city/28-30 highway with just GM stage 2 and no other mods.

thedude411

iTrader: (1)

ya thats low. thats only like 224.4 miles per tank (13.2 gallon tank) (359kms/tank). i usually get around 280/300 miles per tank. so like 21-23mpg

BYFF

alleycat58
"For just stage 2, that's a bit low. Do you have a wideband/have you logged it to see just how rich it's running?"

Negative on that, and I also dont go by DIC, I calculate myself, (miles driven/gallons filled--overall miles/ALL gallons filled blahblahblah...)

And ya, thats low. I dont drive like a maniac, and have intentionally driven under 3k for full tanks to find out.

This is why I think I'm overlooking something else, dealership installed and flashed the gms 2 with the previous owner, and I also paid them an hour of diag, they found nothing wrong (or dont know).

BTW, how do I quote on these forums? Don't see a button for it? Thanx again guys

alleycat58

Lower right, there's a button that says quote post.

Yeah the DIC is hit or miss stock, some are a little happy some are a little pessimistic. Usually once you go with larger injectors, the MPG calculation goes out the window.

I know with my 80s it's off by 10mpg or more but the odd thing is it can calculate the miles to empty properly.

ssyellow

When wot what boost levels do you see?

chris88z24

I'm netting consistant 25-27 mixed mpg with GMS2 injectors and my own HPT tune. The stock DFCO settings suck, but I wouldn't change the RPMs too much because that fuel is what helps cool the cylinders at low speeds.

BYFF

Thanx man, didn't see that

It hits 15 in third, sometimes second but mostly third non-stop.

I'm not changin nothin' myself lol! I'm gonna get a trifecta tune after I install the zzp kit myself tho, I am a bit of a motorhead, but I never messed with ECU tuning.

ssyellow

Yeah that's normal. Idk man that's weird.

Good call on the not tuning yourself, takes lots of experience to do that. P.s. Get a HP tuners tune, not trifecta.

BYFF

Ya thats funny, now that you say that, i wonder if the guy who owned it before me tried tuning it himself... He was a member here I believe, the car came with a "cobaltss.net" decal on the grill

chris88z24

If you plan on keeping this car for any lengthy period of time with mods, I highly recommend buying HP Tuners, a wideband oxygen sensor, and literature on ECU tuning. Read and research before you even plug the thing into your car to scan the computer.

Good luck and have fun.

chris88z24

Oh god, the thing was probably romped on! If you'd like, I can look over your tune and compare it to a stock file to make sure nothing is too far gone to the point where it'll ruin your engine. That type of mileage leads me to believe that the car is dumping fuel for some reason. Could be tune, could be heat exchanger pump is shot and the car is bleeding boost and dumping gas to cool the thing down. Who knows.

I like beer, btw. Just keep that in mind. lol

New guy with Cobalt - Page 2 - Shift 518

Is that your buddy?

BYFF

Good to know, thanx. I read mixed reviews over Trifecta vs HPT. Seems mostly people lean towards Trifecta, but then again i dont know ecu tuning yet.

How would you look over my tune? Are you near me?

Man idk, never met him, he traded it in. I'd like to find out tho, ask him wtf he did to this thing

chris88z24

I reside near and go to school around Albany.

BYFF

I'm up the street from you, in Mc'ville, outside of clifton park.

I understand how engines will dump fuel, to cool cylinders, but i thought a shot intercooler pump should throw a CEl, right?

alleycat58

No, it won't. Mine was shot for God only knows how long, but a LONG time to say the least. No code.

BYFF

O good, that sounds fun. Any tips on checking it myself, besides the ohmage/voltage testing bs?

chris88z24

Yep. Turn the car on, and look in the filler neck in the middle of the front of the engine bay (assuming your intercooler system is stock). It looks like a little ***** with a black cap on it. If the fluid is moving around, you're good.

Make sure you don't confuse the engine vibrations as motion. Easy way is to take a straw and place it in the neck; you'll know for sure then. Also if the fluid is low/missing, the pump is most likely shot.

It's really hard to tell because sometimes it works, and sometimes it doesn't. It can be fine, but the minute you shift into 2nd or hit a bump in the road, the pump could stop again. Piece of junk.

BYFF

Hehe, nice timing bro. Just did that 10 minutes ago, with a butter knife.
So, it flows, stops, bubbles, flows some more, stops, bubbles. No good?

chris88z24

Squeeze the upper hose going to the intake manifold. The fluid should drop.

BYFF

No, the fluid went up when i pinched the hose. But its definitely pumping, i could feel it forcing through my hand, it just completely stops pumping and bubbles every couple of seconds. Is that normal? Or should it be pumping full-time?

And yes, I do feel like I am answering my own question...