the 42#, and 42.5# injectors are being OVERWORKED with a 3.0", and a 2.9" pulley! Go with the 60# injectors. Sunburst SS was tuning a fellow member's cobalt with 42.5# and a 2.9" pulley, and the injector duty cycle is 110-115% at all times. That is not good at all. Just thought you guys might like to know.

 

there is no way that your idcs should be even close to that 110-115 on a 3.0 pully. not sure whats wrong but something is diffentaly messed up

 

2006 called, it wants it's news back.

It was a 2.9.

 

are you serious i want to see further proof of that.

 

depending on location... you guys need to realize these are not N/A cars... tuning is going to be more finicky b/c we are blown... i bet elevation is your issue.. im running 2.9 on 42s and dont even hit 70%

 

So closer to sea level is better?

 

well correct me if im wrong... wut the both stage 2 & stage 3 kits from GM come use 42.5 pounders and im pretty sure gm would upgrade injectors for stage 3 if your gonna spray.. so something must be wrong... however they say on stage 3 w/ spray they are about maxed out

and say i upgraded to 45 or even 60's wouldn't i have to tune for them... its not like they are plug and play is it?

 

i am in NC, which i dont believe can get much closer to sea level, and this has happened on 3 cars, all with 2.9"s and two with GM stage 2 tunes, and the third with High-Compression

NO, not plug and play

 

I am at sea level with stage 2, 2.9 and 42's and its just fine with IDC'S no where near that high (around 85% tops)

Your idc's are at that high ALL THE TIME you say? Find a new tuner.

 

"ALL THE TIME" is the key word. Ed if you and sunburst are seeing that high of IDC something is wrong. Only time I see IDC that high is at 7000+

 

that was on JR's car

 

how about 600-800 sea level?

 

Also interested in the 600 - 800 as I am at 500, what are those people seeing?

 

is that before or after tuning? also the stage 2 injectors are designed to work with the stage 2 and 3 pulley and thats it

 

Bullshit. I have tuned 2.9's and 2.8's with IDC's lower than that. It's one of two things.

1) Your HPT configuration is wrong for the car
2) You're tune is bad

 

hi. welcome to last year.

lean the car out.

 

You say it's topping 115% all the time?
You mean at idle during regular driving (2000 to 3000 rpm range)
What do you mean because if it's topping that durring regular drving your AFR must be astronamicly rich.

 

6mpg in a 4cyl FTW!!

 

it wasn't all the time.....it was going over 100% around 6k rpm and up on the stage 2 tune. It was the 2.9 with the 42's. After the tune the IDC's went down to the low to mid 90's with fueling set at 11.5:1

 

he's basically right.
the injectors appear over-worked because of the huge error in the maf table. i was commanding 11.5 and getting 10.8. the stage 2 tune delivers way more fuel at top end than you will ever need. once your MAF and/or VE tables are properly calibrated, or you lean out your commanded afr, you will see much lower pulsewidths and IDC.

 

bump it up to 11.9:1

 

fwiw ive been at 105-110 (iirc) duty cycle but only at high rpm's, not all the time. Been that way for 3 years on 42's and a 3.0. Id bet to say that besides not re tuning yet for the alt difference between here and Chicago I would bet that Im one of the better tuned cars and seems to be ok.

 

GM Stage 3 runs those injectors with 100 Octane, a 50 shot, and 7000rpms all on a 2.99" pully. The injectors are fine.

 

the injectors lose control at 6400 rpms.

 

GM stage 3 also allows an 8k rpm redline. try that with the 42.5 injectors and valvetrain...