TaTommyWS6

I still have not gotten a straight answer, so here is the question again.
I currently have my LTFTs dialed in at slightly negative but the duty rate is too high on my small injectors,so..

I am upgrading my stock 26.4 lb injectors with 28.6 lb injectors:

Can I just divide 28.6 by 26.4, (which equals 1.08334), and multiply that my my current Injector Flow Rate table?

Thank You!

Tomny

AzzHauler

iTrader: (3)

Sure. If it is off a tad you can just make a small correction. I'd bet you could use those injectors w/o changing the flow rate table. The pcm would adjust part throttle, but you be a bit richer at wot.

Team ZR-1

Your only increasing the flow 2 two lbs in a hour, or as your math says only a .08% difference and if you were going over the 80% duty cycle the 28 lb'ers only will slighty lower it so there is no reason to even tune the flow table.

2 lbs in an hour if broken down to 1 sec it very little increased flow and you would have been better off going with SVO 30s to really make any impact on overworked injectors.

TaTommyWS6

I'm kinda suprised to see you write this. An 8% IFR change is pretty substantial when tuning in one's LTFTs, so why would I not change my flow table?

Well, I wasn't really planning on even changing my injectors, but I figured while the intake was off, I might as well. I got a complete set of 28.6# injectors for $85 shipped, so why not...

Thanks again for all the opinions!

Tommy

Predator

Hey Tommy, maybe those 28s aren't ideal like the SVO 30s, but they're better than the 26ers .

Jim Shearer

How do you know when you have exceeded 80% duty cycle?

TaTommyWS6

There is a chart (Injector Pulse Width vs RPM) that you can reference after logging your car with ATAP, or something similiar...

Tommy

Team ZR-1

You stated that your duty cycle was too high, I have to assune that is at PE and WOT which means the injector has really fallen off/behind before going into PE.

With a 80% rule it would be more like a 6% difference and that comes down per second as very little additonal fuel flow when you need more then that to assure injectors are not falling behind before you get into PE.
2 lbs more flow in 1 hour, divide that by 3600 seconds and then in mSecs is not that much fuel flow to require a PCM tune which was your question, it would well be in the LTFTs window and PCM would auto adjust for that bit more fuel flow.

[quote
Well, I wasn't really planning on even changing my injectors, but I figured while the intake was off, I might as well. I got a complete set of 28.6# injectors for $85 shipped, so why not...

Thanks again for all the opinions!

Tommy


[/quote]

Team ZR-1

Jim this will be close enough to use for N/A engines but for supercharger I would use more like a 50% rule so that there is plenty of fuel to meet the demand at max boost.

RPMs 80%
3000 32 ms
3500 27 ms
4000 24 ms
4500 21 ms
5000 19 ms
5500 17 ms
6000 16 ms
6500 15 ms
7000 14 ms
7500 13 ms
8000 12 ms

Doc99SS

iTrader: (2)

Installing the 28#/hr injectors will help a little. If you are at 100% duty cycle at lets say 6,000rpm (20msec for PW), then these injectors will take you to about 92% duty cycle, which is better than 100%, but still not around 80%.

For $85 and you know for sure that the injectors are good, then I would install the 28s.

I have the same problem as you. But I decided to purchase brand new 30#/hr MSD injectors (for alot more money than $85). These injectors will take me to 85% duty cycle at WOT.

Chris99WS6PWTMET

I have the IFR and Injector Offset tables in jpeg format if you want them. They are from a stock 01 Edit file that I got from J&J's TA so I could adjust my 99 for some 28.8 lb injectors. Its a PITA entering all those numbers but it should be a good starting point for the tune.

TaTommyWS6

Yeah, my stock 26ers are about 85% at max duty cycle. I think these 28ers will be good since it should put my slightly under 80%...

Sure if you could email that to me, it would be helpful. Thanks! TaTommy@optonline.net

Tommy