im gonna try to get my boy on the dyno today with the 2.8, a lil last min but its worth a try

 

Basic Summary:Think of a fuel injector like a garden hose with a trigger nozzle on it. At say 1/4 trigger its operating at 20%. At 100%, its giving you all its got. If you demand say 100%+ from it, it CANNOT give you that. Its at its maximum at 100%. Sorry, no 110%+ like coach demanded of you back in highschool...

Yes, in most, if not all cases, 2.8" w/ 42.5injectors are running fine AFR setups. However, injector failure is likely due to high IDC.

Diagram:
http://static.howstuffworks.com/gif/...on-diagram.gif

A injector generates heat, the plunger can, and most likely, definately, will get STUCK OPEN. Its electronically controlled, demanding more than it can flow is putting excess stress on it, and is going to at some point wear it out.

I think we've extablished that, we have a member who has experienced it on his car. We have members who claim to have seen it occur on other vehicles. What more are you looking for to see that it is not safe?

HOWEVER, it does vary setup to setup, car to car. The only way to know what is going on for sure is to have the appropriate monitoring devices on your car, and have the car correctly tuned.

 

Very good info cds00bsmg. Thank you sir!

 

cool thanks. I think I will be running the 50lb injecters.I don't wan't to screw the motor

 

Good call red. Here is a link to 50lb. injectors incase you need it.

http://www.cobaltperformanceparts.co...ion-p-215.html

 

thanks for the link

 

why dosnt anyone have the 50's then???

 

Anytime bro!

Good question. I think it's because most people are just finding out about them.
I don't know exactly know how long they have been out.

 

I'm still waiting to see all these people running the 2.8 with GM stage 2 to start blowing up. You might find one or two people that have a problem and will blame it on that setup but overall I think you are seeing and will continue to see fewer problems with this setup than you do with the "custom tunes" or the guy that has every after market mod bolted/wired in.


It's very hard to believe that a 2.9" will be all good and then just by going down .1" to a 2.8" your gunna blow


You want to play ? Sometimes you will pay Sometimes stock motors blow up too

 

[/QUOTE]
Like I said, if the car is tuned PROPER it will compensate for the denser air. A lot of "tooners" are using improper methods for tuning where weather will drastically change a tune.

Using our methods, which have already been proven and proven in the ford world for quite some time now work perfect, no one will have any issues.

Cold air is more dense, which means you are seeing a higher frequency on the maf. Depending on how the tune is written, the higher frequencys on maf table are already adjusted and your air fuel will be correct.

The code that is appearing is from part throttle fueling, not wide open throttle fueling. Again, if tuned PROPER no issues will occur with changes in weather, bp, etc

 

The graph in post #1 is with a ZZP 2.85" Pulley I had mistaken when I posted 2.80". The people who state they are getting 90% duty should post their log file as proof.

I don't understand all this debate over 45lb, 50lb, etc. injectors. Just throw in the 60lb's, get it tuned and your set for any future upgrades or you can install a meth/water kit as I stated before.

 

^^ Some people are worried about the 60's being too much with a 2.8, though I haven't seen anyone post anyting up proving they are too much for that load.

 

I have taken my 2.8 off for now but it was a screamer & I didn't hear any knock but lets face it how can you hear it over the screaming SC.

I've only done a couple small mods
Stg 2
Injen CAI
Ingals dampener
Pully Boys 2.8

Now today I was driving with the 3" Stg 2 pully & man what a diferance as the 2.8 gave me much more bottom end & I miss it already so whats the best method of monitoring my motor as I'm old school & don't know alot about the tuner world as of yeat

I do have a ODBII on my laptop & I can get real run time scans or do I just need to buy a system?

Thanks for the heads up on this whole issue as I had no problems, the car ran great but you know it don't take long to damage a motor & I want to get it paid off before I blow it

 

I doubt you will see ayone "blowing up". I wasn't claiming that anyone would blow their motor, just that running the injectors at a high duty cycle will/could eventually lead to injector failure (stuck open).

HPTuners will take care of this concern. It just takes proper tuning.

A wideband oxygen sensor will monitor your AFR. The aeroforce interceptor can monitor knock. (Im not sure if it can monitor IDC). HPTuners can monitor IDC, and IPW (injector pulse width). (Not sure if there are other means to monitor the last two)

 

^^ Agreed. I may just have to stop being such a cheap ass and buy HP tuners. I'm tired of fretting over this and I'm ready to get my hands dirty.

 

Ok so to put larger injectors in I would have to have it tuned afterwards right !

And also if you do run above the injectors limit you can cause engine damage over time can't you from running lean ?

 

A)To run 60lb injectors, yes, you will require tuning.

B)If you were to run lean, yes. From what I have seen, and what others are posting, leaning the car out isn't an issue with the 42.5lb injectors. Their AFRs are fine, and they are running withing safe rich/lean conditions. The injector duty cycle is the only issue.

Here is a earlier post, also giving example of injector failure/problems on a SS/SC due to letting them go static. It can be found on page 4, first post.

https://www.cobaltss.net/forums/show...t=28190&page=4

Here is the post

 

ok the HTP scan that levi will post or if you want ill post it is from my car. 85% is the highest i have seen EVER with 3 different tunes

2.8 South Florida Pulley
42# injectors
Opened Airbox w/ K&N Filter

The only issue i am having at all is a 5* of KR at 5800 rpms it goes back down to normal @ 5850rpms

again like Levi said we are around denver i personaly am at 6800 ft 90% of the week. I have tenative plans to go get dyno tuned after the first of the year. I keep reading that people just tune and dont know what they are doing. I trust the guy that tunes and works on my car more than i trust GM. There is no need to worry an entire group over a few BAD eggs. Yes you mod at your own risk. however keep in mind (this has been said before) each car is different. Hell putting the 2.8 pulley on my car caused the S/C to make noise... cars make noise after you mod get use to it. If your scared to mod then dont. if you want to mod do it. if it breaks fix it and figure out why!

 

Dont you think maybe its the type of 42# injectors used that is giving us different results? idk just asking

 

i dont know.... i am using the gmpp stage 2 42#ers

 

Remember some injectors read higher than their real cycle duty. So maybe our 42's do that?

 

Its your scan so I'll let u post it.

Nice sig by the way!

 

well im guessing im ok im at high elevation (4800) ran my car on the dyno again and my car is running perfect, sucks though cause pushing 16psi with a 2.8 pulley but o well ill see if they will let me post up my screen shots

 

Ok, now what? I have the 60#'ers in now and I am showing an injector pulse width of 14 ms @ 6900 rpm. So, according to this injector duty cycle calculater, I'm still at 85% IDC. Do these calculaters found on the internet give accurate results, or does my car just hate me?

 

No, you are just running to rich!!! Shoot for 860-870 on the 02's