Very high Airflowperrev and ISCposition

[volkri25]

In my idle log my Airflowperrev is around .40 when it should be around .25. I am running BC 272 cams and that should raise it a little from .25. Also my ISC position should be at 30 and its at 70. Is this adjustable. The car was profesionally tuned but seems like the idle and cruising wasnt tuned that well. WOT was tuned great, can pull 30 psi with no knock.

Any help would be appreciated.

*i adjusted my deadtime to about 600usecs and my SD/VE table in that idle range to 39 which seems rather low. Starts out around 55. However doing both these got my CombinedFT and Airflowperrev to around 0 and .29.

 

[volkri25]

here is the log

 

[Meshuggah]

Have you came to any kind of solution? I seem to be having nearly the same problem as you.

 

[LTUDSM]

Adjust your BISS screw to the point where your ISCPosition shows a value of 30. This should bring you to near .25 gm/rev. If your ISC is ut of adjustment,then youll have a high airflowperrev number

 

[snowborder714]

You need to use the BISS screw to adjust the ISC, which should drop the ISC's logged value.

You had the right idea to get AirFlowPerRev down, by adjusting the SD table values and then the deadtime. This will show you if you're unsure (just substitute SD adjustment for MAF Comp sliders).
http://www.ecmtuning.com/demos/fueltrim.html

 

[Meshuggah]

Adjust your BISS screw to the point where your ISCPosition shows a value of 30. This should bring you to near .25 gm/rev. If your ISC is ut of adjustment,then youll have a high airflowperrev number

Are you doing this with the engine running WITHOUT grounding out the computer and diagnostic pins?

 

[LTUDSM]

Are you doing this with the engine running WITHOUT grounding out the computer and diagnostic pins?

Yes,engine needs to be running and at the operating temperature 196+ degrees. turn the Biss one way ,wait couple mins and check the ISCPosition. if its not getting closer to 30,then turn the biss other way.Rad fans needS to be off.If they are on, adjust the Biss to the point,where the ISCPosition will show the value of ~ 34-36. You don't need to ground Anything.....

 

[DSM's 4 life]

My isc possition is reading 100 at idle and when I losen it it seems to go to higer How do I drop my value down when there is no more room for adjustment.

 

[snowborder714]

Have you done a boost leak test recently?

 

[little-razcal]

Just to throw this out there so people with bigger cams will not struggle trying to dial in those setup, an airflowperrev of .25-.28 is more geared to stockish/less aggressive cams at a lower idle.
With some bigger cams you should expect a bigger afpr depending on the brand. A raised idle will also result in different readings. With my Kelford 280's I'm right around .36-.38 at 1000rpm with combined fuel trims +/- 2%..