Inject msec question

[taguru]

I took a scan of two WOT runs. If you look at the second run you see the injector duty rising up to 134%. My question is that at 100% duty, 5,568 rpm the injectors are showing 21.7 msec. I know the injector duty is a calculation so I understand why it continues to rise up to 134% but theoretically shouldn't the msec plateau when the injector duty hits 100%? It continues to rise as well throughout the powerband to 24.1? I'm also curious as to why my fuel trims would flatline at wot? Could that just be because the flow is to fast to read, or that I have the wideband to close to the headers? I was also contemplating sending my injectors to fuel injector connection. I've seen several of you mention them. They suggested to drill them to flow 42 at 58.

[Russ K]

Check your fuel pressure at WOT. Stock injectors will support your set up. It's normal for the STFT's to 0 when in PE. And the LTFT's will also 0 if they were 0 or negative before entering PE.

Russ Kemp

[Montecarlodrag]

Injector duty cycle rises to a theoretical value based on the amount of fuel you're demanding.
134% IDC means you need 34% more injector to achieve the AFR you are commanding.

Depending on your mods and tune, you may need bigger injectors.

[taguru]

Good call! Dropping from 58 to 40 psi at WOT.

[taguru]

Hooked up the fuel pressure gauge at the fuel rail and got 58psi at idle but dropped to 40psi at WOT. Assumed fuel pump not strong enough. Ordered Racetronix RFPK-001 fuel pump kit. Installed today. While I was installing that just to make sure everything else was good I flushed out all the fuel lines and took the fuel rail off and cleaned it out and cleaned the injectors and resealed them. Got it all back together and road tested. Same problem. Injector duty 134% at wide open throttle. Haven't checked fuel pressure yet but assuming it is still dropping. Only thing left that could cause this drop that I can think of is the fuel pressure regulator in the fuel rail. I'll have to check that tomorrow.

[taguru]

Just checked alldata. I thought that was the fuel pressure regulator in the fuel rail. Guess not. I didn't realize that it was in the module that I just had out and apart today. Looks like I'll be dropping the tank again tomorrow.

[Russ K]

Did you check for a plugged fuel filter?

Russ Kemp

[taguru]

yes. replaced the fuel filter at the same time I replaced the pump. also checked pressure between pump and filter. the drop off is coming from somewhere in the tank (defective pump, fuel pressure regulator, or installer error on my part) going to drop the tank today. also noticed after install that i am having to prime the pump first before it will start. starting looking into it online and looks like the majority of people that have purchased this pump kit have the same problem with having to prime the pump. going to recheck my installation and make sure i don't have a leak or kink in the venturi line or main line in the module.

[taguru]

So I dropped the tank again, rechecked all my connections and installed a fuel pressure regulator just in case since I had the tank out again. Didn't see anything wrong with the installation. Put it back together, road tested, fuel pressure is steadily between 58-60 psi at partial throttle and WOT. However, fuel injector duty is still jumping up anywhere from 134-140%? Also since I put the fuel pressure regulator in I have not had to prime the pump.

[Russ K]

Did you go WOT til redline? Are you sure that the stock injectors haven't been swapped for smaller injectors? Is your wideband reading correctly?

Russ Kemp

[taguru]

Look at frame 7320 / 12:17. It was raining so that was the only good run I could get in.

[Russ K]

What is the fuel pressure above 5000 rpm? No way for your mild engine to be maxing the injectors by 5200 rpm.

Russ Kemp

[taguru]

To answer your question. Yes. The wideband is correct. Before the head/cam swap my injector duty was in the 80's at WOT. As far as the injector size I am assuming they are stock. I bought the car with 30k on it from an older lady who was the original owner who made no modifications to it.

[taguru]

Fuel pressure stays at 58psi all the way through redline

[taguru]

The reason why I say the wideband is correct is because I bought the tuning school program 4 years ago and the dynojet wideband 2 at the same time and have been using the pre-configured settings that they put in the auxillary input list for the EIO input on the table all this time and have never had a problem. Maybe the settings are incorrect and it has been wrong all this time? I asked them about this when I bought their program and they said that the dynojet wideband 2 was already pre-configured in the table. It is just really strange that this problem did not exist until the head/cam swap.

[taguru]

Is this not correct?

[Russ K]

Your missing the period before 625

Russ Kemp

[taguru]

Sorry. That was actually the wrong one. The the input I have been using was a pre-configured setting by the tuning school and is set at .625. So the wideband is correct.

[taguru]

If you look at the scan after I installed the racetronix you can see that I am also getting knock in several places. I never had knock until I installed that pump.

[taguru]

Here is the latest scan with wideband connected