Hey,
So I installed my LSJ injectors/'02 fuel rail last night in my '05 Sunfire and proceeded to try and change my injector constant.
I used the scalling method and got: 24/36*0.17800 = 0.11866 ... (0.17800 being my stock constant.)
Fired the car up and it runs fine, the problem is that now my AFR is alot richer.
Stock, the car seemed to be around 12.2 - 12.6 under WOT in PE, now im seeing 11.6 - 12.2
I fiddled with the number abit and tired 0.11800 and no noticalbe change.
Am I right to assume that a smaller number would help lean it out? Do I need to just adjust the number more?
Or am I pissing into the wind trying to get it to lean out to the stock values without changing the VE tables?
Another strange thing is that im getting DFCO as soon as I let off the gas now, regardless of RPM. As soon as I let off the gas the AFR
shoots to 22.4 and stays there till I touch the gas petal again.
Is this because of the '02 fuel rail or because the injectors are now alot bigger?
Any help or suggestions would be hugely appricated guys. I want to get this figured out so I can install the LE5 intake manifold sitting in
my basement...lol
Anytime you change the injectors you are going to have to tune the VE tables. Use the correct constant and then tune the VE tables. As for the DFCO seems normal to me.
FU Tuning
Ahh ok, I thought it might of been that my constant was some how off. Just figured it would be a little closer than it was. I'm still new at this.
As for the DFCO, with the stock injectors it would only kick in under certain situations (Below certain RPMs, ect.) Pretty much as it is defined in the tables.
Now even when I shift gears it cuts the fuel. Never did that before. Regardless of RPM now, if the car is in a gear and I let off the gas DFCO kicks in and thats not what is being commanded in the tables.
Any insite?
Thanks for the info John.
Eh get your @!#$ dialed in
I have tuning to do
how are you seeing your AFR?
what wideband do you have, and did you do a voltage offset?
whats your duty cycle?
12.2-12.6 on stock injectors is impossible.
did you increase fuel pressure?
change your DFCO values to what you like..
12.33 @ 111.67 mph [Oct 2009]
Dyno'd on 08/02/09 - Mustang Dyno:
327.6 WHP 333.6 WTQ [10.1 AFR]
DaFlyinSkwir(LS61) /PJ/ OEM+ wrote:how are you seeing your AFR?
what wideband do you have, and did you do a voltage offset?
whats your duty cycle?
12.2-12.6 on stock injectors is impossible.
did you increase fuel pressure?
I'm using the LC-1, and I was reading those number right off of the guage.
I do have a voltage offset when I monitor it with HPTuners. It logs about .4 AFR higher. From what I was reading you can only adjust the voltage offset in HPTuners. So I'm pretty sure my gauge is reading properly.
Fuel pressure hasn't been touched.
Does that seem to lean for the stock tune? What do you mean by impossible?
The car did have a CAI and full exhaust when I got those AFR readings on the stock tune (Tho I'm sure it doesn't make a huge difference)
I haven't logged my duty cycle since it was the stock tune and I figured there was no need since I was swapping them anyways.
Forgot to add that I had a PE Delay set to 1000RPM on my stock tune. However it was the only thing I touched.
Good advice, I guess I shall do that then. I am kinda curious to see what it is at with the new injectors.
Like i mentioned i have a Scanner file setup for this
This is too complicated. I'm about to get re-tuned with the LE5 manifold and LSJ injectors. What do I tell my tuner? Is he gonna be able with his "sniffer" to get a decent enough AFR for me tuning the VE table for getting the injector constant right. Where does he start with that? Less dyno runs cheaper for me lol Thanks!
"FRIENDS DON'T LET FRIENDS DRIVE STOCK"
DaFlyinSkwir(LS61) /PJ/ OEM+ wrote:how are you seeing your AFR?
what wideband do you have, and did you do a voltage offset?
whats your duty cycle?
12.2-12.6 on stock injectors is impossible.
did you increase fuel pressure?
How is it impossible? I scanned an ecotec with 2.4 manifold and stock injectors and it would drop right to 12-1, I saw no problem with the motor leaning out like everyone says, duty cycle was at about 80%.
13.3 @ 106 mph Cammed
What is the correct injector constant to use for LSJ 36lb injectors then? I kept saying I was getting re-tuned, then lost my job for 3 months. Back to working and making more money. I am getting re-tuned now for real this week or next. I need to know the answer to this? I guess 24/36 *0.17800 wasn't correct as in the beginning of the post?
"FRIENDS DON'T LET FRIENDS DRIVE STOCK"
This is just my experience and opinion, but the "injector constant" is not a magic bullet that lets you slap in bigger injectors and drive off. Most other platforms have slopes, offsets and modifiers JUST for injectors, that's before you even get to any fuel map tuning. For us it just gets worse the bigger the injectors are, but i now believe you should always start with the correct injector constant and tune from there.
The IPW vs VAC table works great as a "coarse" tune. Throw the bigger injectors in, flash the correct injector constant and set the IPW table to 1 across the board. Set up a histo to log AFR error vs MAP (keeping in mind the IPW table is in vacuum), and get that table somewhat dialed in, then fine tune with the VE tables. If you do it this way, chances are you won't have to touch the idle, low rpm/low TPS or coastdown. Also, if your boosted, be careful what you do with the "0" vacuum cell.
Flash the correct injector constant.... but what and how do I get the correct one??
"FRIENDS DON'T LET FRIENDS DRIVE STOCK"
Old constant * (Old injector flow/ New injector flow) = New constant. That's the way i was taught lol. As the injectors get bigger the constant should get smaller.
