Injector Duty Cycle

[jrpmp69]

I guess I am confused. I am a noob at tuning and was just using logic to come to a conclusion that aparantly was wrong. I also have a MAFT setup and just got an AFC that hasnt been installed yet, I'm sure I would have figured out i was wrong when I would have tried to do what I suggested.

Another thing that he can do is raise his base fuel pressure from 38psi (stock 1g) to 42psi(stock 2g), which should lower the IDC's a lil bit.

 

[Quasimondo]

Raising the fuel pressure won't automatically lower the IDC's. The IDC's are calculated based upon engine speed and engine load (which is determined by the amount of air passing through the MAS and the position of the throttle). If you raise the fuel pressure, you'll still have to lean your SAFC to lower the duty cycle.

 

[dnhieu]

this is correct you lower your IDC by leaning out the safc obviously after raising base fuel pressure a little bit...

 

[TurboChrged93]

Wow this thread has really blown up.

Mr. Quasimondo the reasoning behind me having an maf/t and AFC is this is how I compensated for having a larger turbo and injectors. Now that I have my eprom chip... i enjoy the blow through setup and I want to utulize the AFC to fine tune the chip because it is burned for 640/650/660 injectors. So there should be corrections on my AFC, but very minimal. And that is my whole problem. And that is why this thread has been started!!

Current update. With no corrections on the AFC. MAF/T set for 450s I get 40 knock sum WOT. Timing sits about 14-15. But the car pulls like a pig. My fuel trims we're sitting at LTRM - 110 MTRM - 100 HTRM - 90. I then took 11% away from my SAFC across the board and knock sum went to 20 Timing about the same. Now I would continue to take away more fuel. But then in the back of my mind I know that something isn't right. I should not be making such large corrections!!!! Base fuel pressure is set to 38 PSI with vac line off via Aeromitive regulator. Injectors are definitely FIC 650s.

Now... Old man, you said that the MAF/T and SAFC work a bit different. Could you please enlighten me on a further explanation because I was under the impression they work the exact same by altering the airflow signal to the ECU.

About raising the fuel pressure. I thought about that and I thought about that. However, I don't think I wanna raise my fuel pressure as it is my belief i'm getting rich knock as it is. Why would I want to add more fuel besides the fact that my IDC is through the roof. But I don't see how that will lower my IDC because my ECU doesn't know what my fuel pressure is so it's not going to KNOW to squirt less or more fuel in necessarily from raising or lowering it now will it?

I will definitely perform a boost leak test.

However one more thing. Why is it that my AFC is showing I"m flowing 3300+ hertz with no corrections on the MAFT and SAFC. Nothing is tricking the signal so this is a true reading.

My mods are in my profile. But that seems like a hell of a lot of airflow. And thats why my injectors are maxing out.

 

[TurboChrged93]

Thx again guys for all the input.

 

[force it in]

Have you set your mid & WOT settings to 0 on the MAFT?

 

[oldman]

Now... Old man, you said that the MAF/T and SAFC work a bit different. Could you please enlighten me on a further explanation because I was under the impression they work the exact same by altering the airflow signal to the ECU.

Don't worry about it, it was for jrpmp69, everything you just said is correct so let's leave it that way.

However one more thing. Why is it that my AFC is showing I"m flowing 3300+ hertz with no corrections on the MAFT and SAFC. Nothing is tricking the signal so this is a true reading.

Like already said, boost leaks and maft calibration, there are also many threads concerning how inaccurate the GM maf is in blow through.