clumsykx

I am going to pursue the "bypass check valve" fuel tuning option on the cobalt here in the near future. This mod is mainly used for boosted aplications. I was planning on using an aeromotive fuel managment http://www.aeromotiveinc.com/pdetail.php?prod=32 to attain proper fuel from a "boosted" auxilary fuel pump. The pump would be placed in the stock fuel line with the input before a check vavle and output after a check valve preventing backflow. Thus the managment unit under boost would turn this pump on creating more pressure. Yey!
If anyone ses that the ECU would through a **** fit and give me the finger, lemme know. I need a 3 bar map also. i will do research on this also.
Please If you don't have any knoledge about this dont post here, I am not here to answer questions I am here to have questions answered and problems solved. Thanks guys!

RedBaseBolt

The only way thats gonna work is with a stand alone fuel system or wait till HP Tuners cracks our ECU.

It will simply not add fuel and get confused when it sees positive pressure instead of vacume.

Also the 3 bar map will do you no good unless u again , either get stand alone or a tune from HP Tuners to let the ECU even see boost.

clumsykx

Yeah well this setup is my standalone fuel system. In a sense. Anyways the map sensor I dont know. I suppose ill figure it out somehow. Hahn told me the stock one would work under boost. But im looking for the specs on it. the part number is 16212460 53341 delco 5 volt. The 5 volt is really what makes me jump. Thats what the jbody crew uses for boost.

clumsykx

So I found this http://www.powerandsignal.com/docs/Products/pressure_sensor_brochure.pdf#search='map%201621246 0' and it shows that the stock map sensor is capable of three bar. since 1 bar equals 100 kpa and that this sensor provides 300kpa max which would be 3 bar. and capable of 5 volts. Justifying that this sensor woud be fine and the ecu can use it. Also the s-10 forums show that the same part number is used and that they run 7 pounds with no ecu issues.

zinner

That fueling solution looks promising.

As for a 3 bar MAP I think you won't need that unless you have a way to tune the computer.

clumsykx

What i meant was the car already has a 3 bar map so i wont get an overload cel like a 1 bar. So i think i am safe. OR GM put that in there to know when someone was breaking stuff on purpose. We'll find out. Give me time and money if you want. Thank you for the positive reply zinner.

NJHK

You just explained basically what every FMU does. It increases the fuel pressure inside the fuel rail by intercepting and restricting the returned fuel on the return side.

Only problem is, you still don't have control over your injectors...but guess what? Your computer does! Yup, your computer could easily change the duty cycle on the injectors and simply slow down the amount of fuel being sprayed because basically, it wasn't programmed to see anything over atmospheric pressure.

Also, people have this misconception that you can just wire up a 3 bar map sensor and it will work fine...it won't. Stock, your car has a 1 bar (1 bar absolute pressure, won't read over atmspheric pressure) sensor. Now because of this, you change your MAP sensor without any type of re-programming, you computer will freak out basically...will have trouble starting or it will start and run completely lean. Your computer though will probably learn to run ok with the new bar map sensor but fact still remains, your computer is not programmed to comphensate fuel over atmospheric pressure (boost).

Basically, a 2 or 3 bar sensor is there to be computer friendly. If you have say a 2 bar MAP sensor, it has the ability to read boost BUT your computer still needs to know what to do when it's at those levels. Look at the Cobalt SS/SC guys...why do you think their upgrade kits come with an reflash yet they have 2.5 Bar MAP sensors? It changes injector duty cycle at idle, changes spark timing and changes fuel maps during boost (adjusts according to engine load).

Hopefully this makes sense and you have a better understanding. If you have any questions, just ask.

IonNinja

heres where I'm lost...05+ 2.2's are maf equipped...why would you need to worry about an map sensor?

Toyotech

lol, read my mind as i was reading this... of course thats what the 5 volts is at, but i would worry about other problems over pegging 5 volts... many ways around that, not modding a dsm here. no reason to ditch a maf for map either, tuning may be a little easier and sometimes more accurate but its a great design.

Halfcent

I've been looking in to that very question and should have a good answer after this weekend. Our cars use a combination MAF and IAT sensor, and then a separate MAP. My guess is that with temp and flow, the computer can determine incoming air density, and then make it's determination on injector pulse width. Then, the MAP has to do the with the returnless injector system, and pressure regulation. Like I said, I'll know more in a couple days.

Toyotech

many automakers run a maf...having a map along with it is useless and you are correct with your guess... but for pressure regulation the "regulator" is usually in tank off the fuel pump...stupid emissions

NJHK

I kept mentioning MAP sensor cause he did...I figured he was trying to do something real creative.

Bika

iTrader: (3)

the most anyone has done is speculate on how the ecu will react. the computer COULD easily change the duty cycle and or pulsewidth of the injectors, but will it? the computer could reduce engine power, partially close the electronic throttle, pull timing, use limp mode, or change any number of parameters but ive yet to see actual data or see any proof of what the ecu actually does when it sees boost. until someone actually tries something, all we can do is guess. hptuners and hahn are rumored to be "working on it" but havent revealed what is standing in the way or how it works....probably to secure a dependent customer base. my vote is to learn by doing. nothing ventured, nothing gained

NJHK

Well I said what I said from personal experience having a 2003 ECU (2004 Updated Flash before the GM S/C Flash) and seeing other J-body owners with 2004+ J-bodies have issues because the computer will do everything it can to stay at a certain a/f ratio.

Granted, you guys aren't J-body owners but for having Pre-Cobalt Computers and they were as strict, it's a defenitley possible that it will do the same for you guys.

RedBaseBolt

I'm tempted to build the engine up and get a turbo installed and run no boost and see if the computer changes anything since there is now a turbo in the way of the exhaust.

Then increase from there. Say 1 psi for 2 weeks, 2 for 1 and so on. Just an idea really...

NJHK

It has less to do with the physicality of a turbo being on your motor and more about compressed air causing pressure in your combustion chamber to reach above atmospheric pressure.

And to save you time, I'll tell you what will happen: Your motor will slowly start to lean out without any fuel modifications or fuel management. I know this cause I've seen it first hand on my vehicle. I was running stock injectors and no fuel management for a short period of time and at 2 PSI, it was hitting 14.x a/f ratio without even being at full throttle.

Also, good luck finding a wastegate spring that allows you to stay as low as 1 psi...smallest I've ever seen is 5.

RedBaseBolt

True, good point. I'll just wait

NJHK

Good idea. Don't worry, things will get better for the 2.2's aftermarket.

clumsykx

I found by adding a 4.7 volt zenor diode would hold the map from peaking out and keeping th ecu happy, inserted on the neon green wire of the map sensor.
I must figure on the maf sensor and do more research, if anyone has useful info on this the 2.2 should be boostable with no problems.

sheek360

i dont have knowledge in this at all but it sounds like you really want to pursue this, good luck with the project. I cant wait to see your results! THUMBS-UP!

clumsykx

I tested teh MAFS and all that needs done is to block any frequency over 7.6 k a maf translator should do fine.

clumsykx

Well i own a civic now but I jsut wanted to let you guys know wohever bashed me about my idea will the fuel pump boosting that it works huh? Thats what they are doing to boost the slobalts. But in all honesty I want my eco back.....really bad!

Bika

iTrader: (3)

haahhaha. slow cars FTL. shoulda kept yer balt dude