Hello. I have 550cc primaries and 1680cc secondaries, T04S single, PFC. I tuned with Jeff48 and we had a max of 78% injector duty at 15 psi with 10 afrs for the whole day. On the way back from tuning it was the same. It rarely went above 72%. It was fine for around 2 weeks. Then one day I did a highway punch to about 7k RPM. Boost was normal and peaked at 15psi, but my max injector duty was 95%! Now it consistently does that and I am a little frightened. I have the resistors in the 1680s if that makes a difference. What can explain the change? While we were tuning we could do 7.5k RPM runs over and over and have consistent 70% duty. I am afraid to push the car now because something is certainly wrong. I have talked with Jeff and there is no reason it should be doing this. Any idea why it is doing this? I installed the injectors correctly. I've had 2 people check my work there.

Thanks everyone, your help is appreciated.

 

Chris

Have you tried substituting someone else's injectors. You may have a defective or sticky injector. From the sounds of things however, you may want to test the secondaries first.

Jeff

 

Yea I will do that. I need to find a volunteer with 1680s.

Thanks, I need to get this thing running right. I miss those few weeks it ran right.

 

Your logged duty cycles are what the PFC is telling the injectors to do, not some fault of the injectors. This is likely an effect of running in map cells that were not tuned before or perhaps boosting on a cold motor. Map problem should be obvious looking at the maps as you are showing a 20% increase in fuel delivery. IAT or water temp sensor failure could do it too, not much else that would add 20%. I assume you did this with a warmed up car, if you did it with low water temps you would see 20+% more injector duty cycle as the warmup maps add alot of fuel when coolant temps are low.

 

I will be pulling the secondaries in the next few weeks and taking them to be tested.

Every time this happened the car was fully warmed up.

Thanks for the help everyone. I'll post the results of the injector test.