Injector Duty cycle

[TURBOGNX]

have a 1988 Fiero GT with a swapped stock L32. I noticed that my injector duty cycle under WOT was getting up to 99% and I couldn't find any info, or get any answers to why a stock engine would be running out of injector.

I decided to change the injectors and put in a set of 42# injectors and changed the fueling to get it back to 14.7. I took it for a good run and it seems to run ok, but when I got back and looked at the data it's now saying my injector duty cycle is at 119% at WOT.

How can that even be possible?

[SiriusC1024]

Good question. Let's see the tune.

[TURBOGNX]

Good question. Let's see the tune.

Here it is.

[5FDP]

Why are you asking for so much fuel?

You have the BASE commanded AFR at 11.8 but then you also are adding in fuel from the RPM adder. There are times where you could be asking for 9.0 to 10.0 AFR.

Zero out the RPM adder table if you only want to command 11.8 AFR in power enrichment. Then retune the MAF curve to get your fueling on point.

[TURBOGNX]

Why are you asking for so much fuel?

You have the BASE commanded AFR at 11.8 but then you also are adding in fuel from the RPM adder. There are times where you could be asking for 9.0 to 10.0 AFR.

Zero out the RPM adder table if you only want to command 11.8 AFR in power enrichment. Then retune the MAF curve to get your fueling on point.

Newbie question, couldn't that cause not enough fuel under boost?

[SiriusC1024]

That setup is for supercharged like the GTP.

Regardless, DC should still be a lot lower, especially given flow rate.

I wonder if it's your channel settings? For Injector Pulse width and RPM you're using the general sensor right, not the engine-specific? Sometimes the specific does weird things.

Math for IDC: IDC = IPW/(1000/(RPM/120))

https://forum.hptuners.com/showthrea...inj-duty-cycle

[TURBOGNX]

That setup is for supercharged like the GTP.

Regardless, DC should still be a lot lower, especially given flow rate.

I wonder if it's your channel settings? For Injector Pulse width and RPM you're using the general sensor right, not the engine-specific? Sometimes the specific does weird things.

Math for IDC: IDC = IPW/(1000/(RPM/120))

https://forum.hptuners.com/showthrea...inj-duty-cycle

L32 is supercharged. Series 3 with Series 5 blower.

[N2speed]

Did you check fuel pressure?

[TURBOGNX]

Did you check fuel pressure?

Yes, fuel pressure is set to ~50 and rising with boost. I also recently upgraded to a 340 LPH pump to make sure it had all the fuel it wanted.

[TheMechanic]

Screenshot 2023-06-11 141355.jpg

[TURBOGNX]

Well, I still don't know why the stock injectors were maxing out on a stock engine, but I did finally find out why it was even worse with the 40# injectors. I sent the numbers off to Witch Hunter and found out that Kenne Bell fucked me over selling these with a chip as 42# injectors when they are actually only crap 28# injectors. All the years of money and frustration with these injectors to find out it was all a scam.
Back to starting board yet again.
Thanks for everyone's help.

[TheMechanic]

Got to thank blindsquirrel for this. Put them on almost everything now.

https://www.ebay.com/itm/274424906026

[SiriusC1024]

Needs adapters. I hate adapters. Fire hazard to me, but not to some.

https://zzperformance.com/collections/3800/fueling

Green Giant or Deka 60. They're on ebay, too. Data exists.

[TURBOGNX]

Got to thank blindsquirrel for this. Put them on almost everything now.

https://www.ebay.com/itm/274424906026

$55 for 8, and they actually work? Most sets of 6 I've seen are over $300

[SiriusC1024]

Probably. Listing says new (other) and there have been hundreds of sets sold by that seller. If you go with these don't forget your adapters and pigtails.

[TURBOGNX]

Got to thank blindsquirrel for this. Put them on almost everything now.

https://www.ebay.com/itm/274424906026

I put in an order for these, now I wait to see.

[TURBOGNX]

Thank you everyone for your help.

[TheMechanic]

I have installed no less than 20 sets of these since blindsquirrel turned me on to these. I have recommended them to many people and not one single bad word from any., They are brand new not rebuilt. E85 injectors with GREAT data.