What the heck is the approximate injector duty cycle on stock boost and on a completely 100% stock car? I can't ever seem to get an answer. Anybody...please?

 

WEll, you're gonna get two answers:

A.) near 100%

B.) WAYYYYYYYYYYYYY TOO MUCH YOU'RE GONNA BLOW YOUR ENGINE

P.S. I think the answer to this question usually leads to name calling and flaming and all sorts of This Shop Vs. That Shop.....

 

^^^^^ +1000000000

JWT kit's fuel "solution" is sketchy at best. And that's at completely stock levels.

 

Instead of supplying larger fuel injectors, the kit has some sort of fuel pressure riser, I guess its a more efficient way to increase fuel w/o larger injectors?? Correct me if I'm wrong.

 

I agree. The stock 260 (or 280 I forget) injectors are at 100% duty cycle at WOT without a doubt. It handles increased fuel requirements like the Vortech kit, increasing fuel pressure. Unlike the Vortech kit it uses a 4:1 regulator on the stock pump assembly to do this. It is of course boot referenced.

 

I see...so at full boost the injectors are maxed out and it uses a rising rate fuel pressure regulator....

I think the stock injectors are 290cc at 3 bar or 330cc at 3.5 bar.

 

Correct. At full boost/WOT the injectors would be open 100% and the increased fuel delivery demands are met by increasing the fuel rail pressure. You should have a boost signal line going back into the fuel tank area. In fact if you pull the tray out of your glove box you should see the line going into the top of the fuel pump assembly. It goes to a 4:1 regulator thats mounted on the bottom side of the pump assembly.

 

Thanks, I don't actually have the kit.. but was considering it for my 06(completely stock). I miss FI...

So is it dangerous for the injectors to be at 100%? What are the potential consequences. Isn't there a higher chance of failure when relying on such high fuel pressures? I know most recommend no more than 80% injector duty cycle...

Im thinking it may be fine for a completely stock 06 with a modest hp gain...

 

The duty cycles follow a stock duty cycle table. The JWT does not control injector pulse width...only timing retard via the split second box. The kit uses a raising rate FMU, in order to run much higher fuel pressures than stock.

That said, the question to ask, is what are the MAF voltages across the rev range. This will be a good indication of IPW. If that MAF gets close to 5V, that is probably very close to 100% duty.
I dont know the answer to this question, however, as we havent logged MAF or IPW on the JWT kit yet.

 

There are post about the JWT kit going into a limp mode on really cold days if you rev the engine to redline. That would be a good indication that he ecu "think" it's seeing something it does not like. It likely could be 100% duty cycle.

 

For whatever it is worth we have easily installed more JWT kits than anyone.

Never ever seen a situation on the road or track where the stock kit has been leaned out and not been able to deliver the fuel needed with the supplied Boost Pressure Regulator...

FYI limp mode is at 4.8 volts and we have never experienced limp mode with a stock kit and at stock boost at the waist gates.

Good-luck.

M

 

First off..thanks for the info. So basically what you are saying than is the injector duty cycle is never 100% on a completely stock kit... even at WOT?

 

Zman you can give japtrix a call they may be able to help you if your intrested in the jwt kit as they are dealers. I think if you stay stock you'll be safe with it. Once you go with TP's and exhaust you may have to change the fuel system. If your not looking for crazy power, you may be able to pick up a used aps fuel system and that should solve your concerns. I believe brooke is running a built motor with his aps tt with larger injectors and getting good results.

 

Thanks CaptJ....I am currently no longer in FL though...otherwise I would consider Japtrix. The thing with me is I have this tendency to change cars pretty often. I wouldn't be changing anything on my 06...and I want everything to remain as stock as possible so I can just take the kit off and sell the car and the kit separately whenever I want...probably when the 09 Z comes out.

If you remember I also had an APS ST and was more than satisfied with my 380 whp. I honestly didn't even care to have that much power...so I'm thinking it may work out well for me to get the JWT kit just to have a bit more fun with my stock car..

 

As mentioned by Sharif the ECU signals are not modifying at all with the stock JWT kit so whatever the duty cycle is for the stock car it is for the JWT kit, the way to deliver more fuel is to increase the fuel pressure which seems to work fine with the stock kit and stock boost so it will work fine for you. When installing tp's and/or bigger exhaust it will increase boost and tend to lean out towards redline.

 

Thanks for all the help everyone...much appreciated. I understand it 100% now