ok im in the process of tuning a 05 eco sunfire. using stock cobals ss 36# injectors. with a 16g turbo setup. i changed the injector const. to the new number i came out with. which was .118666 <stock is 24 lb> new are 36lb. 24/36=.66666 x stock injector const which is .17800 which gives me .118666. the car will only start for 5 seconds then die. but if i put it back to the stock eco injector const it starts and runs.? any help would greatly be appreciated.
PJ
Start with the calculated constant and move the number closer to the stock constant until you get it to idle right.
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Hahn Stage II - Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
Based off your thread on HPT's site, your 2.5 BAR MAP sensor is your problem....
P&P Tuning
420.5whp / 359.8wtq
calculate the correct constant and leave it alone. get it to run by adjusting your VE offset until it idles, then fine tune from there. (IE getting it to drive, etc). if you have the 2.5 bar you are going to have to do the fake 2.5 bar tune. if you end up maxing out the VE offset and still need more fuel up top, adjust the IPW multiplier vs VAC in the 0 kpa column. (i also adjust the 5kpa column too, just in case)
12.33 @ 111.67 mph [Oct 2009]
Dyno'd on 08/02/09 - Mustang Dyno:
327.6 WHP 333.6 WTQ [10.1 AFR]
oh yea, forgot to add. before adjusting the VE offset, to get mine to run i added 40 to my idle table, then adjusted the offset..
12.33 @ 111.67 mph [Oct 2009]
Dyno'd on 08/02/09 - Mustang Dyno:
327.6 WHP 333.6 WTQ [10.1 AFR]
ImPhat0260/Cavattack2000 wrote:Based off your thread on HPT's site, your 2.5 BAR MAP sensor is your problem....
I was going to ask about the MAP sensor. The symptoms sound about right for that cause, but no info was provided so I wasn't too sure.
" To study and not think is a waste. To think and not study is dangerous. "
More info is needed, as mentioned.
Further to that, I would never recommend to anybody to play with the VE offset to get the car to idle with an injector change. If your constant is wrong, it's wrong. I have done a fake 2 and 3 bar tune now and have had both idling like stock without ever touching the VE offset. I've done so with 36 - 96 lb injectors.
Beyond even that, the injector constant theory is a best guess scenario and in all instances it has proven to be flawed and incorrect. Use it to get a "base" constant, then start the car. If the WBO2 shows lean, you know which way to go with the constant. If rich, same deal.
You give the car what it wants to start. If your idle tables were perfect before you change the injectors, there is zero reason to fart with the VE tables or offset. It's all constant.
If you were doing this on a new engine with different cams, intake manifold, LS1 TB, etc - which has drastically different flow characteristics from stock - then fine that's an instance to play with the idle VE **once the car is close to idling fine**.
Good luck.
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
SweetnessGT wrote:More info is needed, as mentioned.
Further to that, I would never recommend to anybody to play with the VE offset to get the car to idle with an injector change. If your constant is wrong, it's wrong. I have done a fake 2 and 3 bar tune now and have had both idling like stock without ever touching the VE offset. I've done so with 36 - 96 lb injectors.
Beyond even that, the injector constant theory is a best guess scenario and in all instances it has proven to be flawed and incorrect. Use it to get a "base" constant, then start the car. If the WBO2 shows lean, you know which way to go with the constant. If rich, same deal.
You give the car what it wants to start. If your idle tables were perfect before you change the injectors, there is zero reason to fart with the VE tables or offset. It's all constant.
If you were doing this on a new engine with different cams, intake manifold, LS1 TB, etc - which has drastically different flow characteristics from stock - then fine that's an instance to play with the idle VE **once the car is close to idling fine**.
Good luck.
-Chris-
after you get the constant from the equation, yes, i would use VE offset to get the car to run properly. VE offset allows values greater than 100 in the cells as you probably know, so if it needs a value over 100 to get running, it needs a value over 100.. by no means am i an expert, im just speaking from my experience tuning my car with a fake 2.5 bar setup, which i have had no problems with since i kept the calculated injector constant and changed the VE offset.
everyone probably has their own way of tuning, i prefer to tune with VE instead of the injector constant..
12.33 @ 111.67 mph [Oct 2009]
Dyno'd on 08/02/09 - Mustang Dyno:
327.6 WHP 333.6 WTQ [10.1 AFR]
