High AirflowPerRev after installing Cams

[Chicken Patty]

Hello,

I've noticed that ever since I installed my Kelford 272 Cams, my AirflowPerRev is really high at idle. I've gone as far as -25% on the 500-600Hz sliders (GM MAF idles at around that) and I can get it close to about 0.29-0.33 gm/rev, but at this point it's super lean and the o2 voltage won't cycle. I have to add an insane amount of Injector Dead Time (+550-600) to get it to start cycling, just doesn't seem right.

Is this normal?

Right now, car drives perfectly fine, idles great but AirflowPerRev is at about 0.40-0.43 gm/rev on idle. Just not sure if it's normal or I'm doing something wrong, I just can't figure out what since on stock cams I had the car dialed in to a perfect 0.24-0.26 gm/rev on idle.

 

[BoostedBeaver]

After my cam install (Delta hks) and some tuning, my car idles at .28 or so. You must make sure that your global is dialed in correctly before tweaking this step, as any change to global will be a waste of all the time you spend now at idle. If global is dialed in correctly do what you need to do to get the revs down to .28ish and adjust your fuel accordingly. FWIW my deadtimes are around 600ish as well, but that is what it took to get everything in check. What injectors are you running and what is the size? Mine are Delphi 950cc seat & ball, peak and hold (of course) and fuel pressure is set at 42.5.

 

[Chicken Patty]

After my cam install (Delta hks) and some tuning, my car idles at .28 or so. You must make sure that your global is dialed in correctly before tweaking this step, as any change to global will be a waste of all the time you spend now at idle. If global is dialed in correctly do what you need to do to get the revs down to .28ish and adjust your fuel accordingly. FWIW my deadtimes are around 600ish as well, but that is what it took to get everything in check. What injectors are you running and what is the size? Mine are Delphi 950cc seat & ball, peak and hold (of course) and fuel pressure is set at 42.5.

Hello, global seems to be dialed in correctly, my Lo and MID fuel trims are give or take -1% both so that should indicate that the Global is set pretty good.

I am running PTE 1200cc Injectors, stock FPR. My profile is updated with all my mods if you want to take a look. Current dead time is 320.

 

[BoostedBeaver]

I know you already know this and a thousand people have said it but you might want to look into an AFPR. Not going to beat a dead horse so here on with your question. I was told that the normal deadtime for my 950's was 300ish so I imagine yours would be a little higher. After setting the global, changing the airflow, and adjusting the deadtime I have the proper airflowperrev and feel much better. FWIW my deadtimes were in the low 3s high 2s with stock cams.

 

[Chicken Patty]

I know you already know this and a thousand people have said it but you might want to look into an AFPR. Not going to beat a dead horse so here on with your question. I was told that the normal deadtime for my 950's was 300ish so I imagine yours would be a little higher. After setting the global, changing the airflow, and adjusting the deadtime I have the proper airflowperrev and feel much better. FWIW my deadtimes were in the low 3s high 2s with stock cams.

I had an APFR, but it went bad flooding cylinder 1, running the stock one for now. I'll give this another go guys, guess I'll have to go crazy with the deadtime

Thanks for the help guys.

 

[BoostedBeaver]

No problem. Please post the results so that others can view the thread and get some insight.

 

[Chicken Patty]

No problem. Please post the results so that others can view the thread and get some insight.

Will do, might need a day or two, but I'll post up

 

[Chicken Patty]

Just didn't have the chance to post last night, but I gave it another shot.

The only way to get the air flow down to about 0.26-0.29 on idle was to run 780 for injector dead time, if I would keep the dead time lower it would not idle on closed. So I would have to bump up the dead time and the Maf Comp slightly as well. Then when I finally got everything dialed in (numbers wise) the car drove crappy even after zeroing out the MID and LO trims. Had to play with some idle air smoothing, BASETIPIN, car just didn't drive right.