Injector Duty Cycle Question??

[3.8L V-8 eater]

Hi, to all

I'm looking through a few logs on my Power Logger and noticed that my IDC was over 100% at WOT...Normally it is at 80... That is with spraying alky also with a new alky pump just put on back in April?? Also what should my maf readings be with the Extender Extreme chip?? They seem to reading low...

 

[Boost231]

Post the log as well as a good log

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[3.8L V-8 eater]

Here is the log in question

 

[aminga]

You're a smidgin rich under boost. I see 10.0 on the wideband which isn't helping the duty cycle.

 

[3.8L V-8 eater]

You're a smidgin rich under boost. I see 10.0 on the wideband which isn't helping the duty cycle.

Yes there were a few blips in the log that got down to 10.0 but most of the 2nd half of the run AFR were around mid 10's.....Other logs that the IDC was around 80 were about 11.0 AFR...Do you think that is enough to effect it that much???

 

[aminga]

I guess the other question is has it always been at 100% duty cycle?

 

[3.8L V-8 eater]

I guess the other question is has it always been at 100% duty cycle?

No....That was the reason for the post it is usually been around 80% although I did go from a 6262 to a 6265 turbo which I could see having a little effect but not that much....

 

[aminga]

I'd be checking the fuel pressure.

 

[BobbyBuick]

ID BE CHECKING FUEL REGULATOR FOR A LEAK AND PUMPS .I never like to run much over 80-85% injectors not likey.and if it chenged like that something is wrong IMHO

 

[we4Mateo]

PL can be weird with duty cycle. Is there a way to see pulsewidth instead? Either way, if it unexpectedly jumped, I'd be suspect of my fuel pump going bad.

 

[Eric Stage I]

You do not have a chip that corrects based on air/fuel ratio. You have a chip where fueling is based on mass air. So, what dictates how much fuel you get is the mass airflow reading.

The only way your duty cycle could have jumped up, is if the MAF reading is higher now than it was before, or you are operating in a higher RPM range than before.

So, I would look at the old logs, and see what the MAF reading was, and the RPM range, and see what is different.

The duty cycle on PL is calculated directly from the pulsewidth and RPM in the ECM's brain. It includes the injector open/close time (offset). So, 100% duty cycle is the max you can have and still pulse the injector fully. If you push it farther, you start overlapping with the last pulse, and you will transition into a static condition (no more pulsing), and sometimes you will get a tad extra fuel in that case. This would occur in the 100-105% duty cycle range. After that, no more fuel.

Regards,
Eric

 

[3.8L V-8 eater]

You do not have a chip that corrects based on air/fuel ratio. You have a chip where fueling is based on mass air. So, what dictates how much fuel you get is the mass airflow reading.

The only way your duty cycle could have jumped up, is if the MAF reading is higher now than it was before, or you are operating in a higher RPM range than before.

So, I would look at the old logs, and see what the MAF reading was, and the RPM range, and see what is different.

The duty cycle on PL is calculated directly from the pulsewidth and RPM in the ECM's brain. It includes the injector open/close time (offset). So, 100% duty cycle is the max you can have and still pulse the injector fully. If you push it farther, you start overlapping with the last pulse, and you will transition into a static condition (no more pulsing), and sometimes you will get a tad extra fuel in that case. This would occur in the 100-105% duty cycle range. After that, no more fuel.

Regards,
Eric

Eric do you think the maf readings are low?? My buddies car doesn't make as much power as mine and he has an extender chip...His maf readings are higher than mine....

 

[bison]

Throw some voltage at it and see if the dc drops. I missed if you had a new wire harness in the injectors also. I've seen DC drop hit wiring and new harness.


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[Eric Stage I]

Make sure you have your powerlogger set to Extender Extreme. You are over 500gr/sec.

By the way, you should still look into your fuel system and pressure under boost. You still might have a problem there. I was just making the point that your duty cycle will not go up on it's own when you're lean.