I'm working on a 93 FD and I noticed the most odd pattern where when cold, the duty cycle of the injectors are reaching 70-80% as expected while as soon as the car warms up, the injector duty cycles NEVER past 49% after 4500rpm and actually drop to 34% and then slowly increase. I have never seen this type of issue before but I certainly feel the power loss after 4500rpm.

I am including the data log and have highlighted the point of issue. Has anyone ever ran into this situation before?

Unported engine
3" cb
stock fuel setup
emissions deleted
PFC

 

I'm assuming that would be because of the secondary injectors kicking in therefore reducing the overall injector duty.

Have a look at the last column of the log file and you will see when the secondariness kick in. Best thing to do is to open the log file in Excel.

 

Does not do that on my car so I find that hard to believe
Log can be opened via Excel. Just select "open with" and it should load up chart style

 

Yeah I know how to open the log file in Excel. I'm the one that suggested it, remember?? As a matter of fact I have it open now, and I can see that when your secondary injectors open up then the injector duty drops down. Mine does the same. I'm new to tuning myself so maybe someone else can explain it better.

 

Found the issue and I'll post it here for potential others!
Injector duty issue fixed, had an occasional stuck secondary front injector. Injectors were never cleaned and had buildup of crud in the rail.

Replaced both secondaries and inspected/cleaned primaries and now I get no loss of power after secondaries kick in!

 

Your Canadian fuel must be of a poor grade.

I have over 50K miles since my rebuild in 1999. Live in hot Houston area.
I run Chevron fuel which includes injector cleaner. Once a year I put about twice the dosage of aftermarket cleaner in the tank and go out in the country for spirited driving.
No problems here.

Try a better brand of fuel and cleaner.

Running a little premix will help with that and also increase engine life.

 

Verify that your fuel system is working 100% correct without any leaks. Low fuel pressure will require more duty cycle to flow same fuel.