Stock air box too rich for anyone else at WOT?

daemon · 07-29-2005, 08:05 AM

Has anyone else noticed AFRs that are significantly richer than what is in the primary fuel map when using the stock air box?

I had been playing with a short ram, but took it off last night due to insanely high and non-stop fluctations of IAT. When I first put it on I noticed that the loads I was hitting were >3. Then I noticed how rich I was running compared to the fuel map so I started tweaking the intake calibration so I was running about inline with the fuel map. And no surprise, my loads dropped under 3 once again since load is in part derived from how much air the MAF says is entering the system. By calibrating the intake I fixed the lie.

Anyway, after putting the stock box back on, I noticed again, that even the stock box is running richer than the fuel map calls for. So it almost seems to me like the stock intake calibration is being a bit forgiving of the stock box and telling the system it is letting in more air than it really is. So I'm wondering if it just me, or is anyone else seeing their stock box running richer than they expected? If I adjust the stock box calibration, I'd bet my loads drop sub-3 again.

jays05 · 07-29-2005, 08:13 AM

The stock narrowband O2 sensor is really inaccurate at anything besides 14.7 AFR. I target 11.4 AFR in the lower right hand corner of the fuel map and get 10.8-10.9 AFR on my LC-1 WB02.

You also point out something that I noticed when I first put on my Injen CAI (before the MAF rescaling). Aftermarket intakes that flow more air than the stock airbox and fool the MAF sensor and lean the car out (which we all knew), but they also mess with the calculated engine Load which is used in just about all of the different maps. So you also end up with different AFR targets, timing, etc. MAF scaling is key with aftermarket intakes (besides the k&n typhoon and possibly others). After scaling mine the loads are back to normal.

daemon · 07-29-2005, 08:25 AM

Except the stock O2 sensor isn't used at WOT (I'm using an LM-1 for tuning, FWIW). The ECU is pretty much guessing at how much fuel to put in at WOT, so maybe it is designed to guess with a bit of error on the rich side. However, if we aren't hitting our fuel points in the map, doesn't it make sense to scale the intake calibration so that we do start hitting the fuel map values? Otherwise what's the point in putting values of meaning in the fuel map.

STirish · 07-29-2005, 11:50 AM

Quote:

Originally Posted by daemon

Has anyone else noticed AFRs that are significantly richer than what is in the primary fuel map when using the stock air box?

I had been playing with a short ram, but took it off last night due to insanely high and non-stop fluctations of IAT. When I first put it on I noticed that the loads I was hitting were >3. Then I noticed how rich I was running compared to the fuel map so I started tweaking the intake calibration so I was running about inline with the fuel map. And no surprise, my loads dropped under 3 once again since load is in part derived from how much air the MAF says is entering the system. By calibrating the intake I fixed the lie.

Anyway, after putting the stock box back on, I noticed again, that even the stock box is running richer than the fuel map calls for. So it almost seems to me like the stock intake calibration is being a bit forgiving of the stock box and telling the system it is letting in more air than it really is. So I'm wondering if it just me, or is anyone else seeing their stock box running richer than they expected? If I adjust the stock box calibration, I'd bet my loads drop sub-3 again.

Did you reset the ECU? It may still be using the old A/F Learned values from the short ram. I bet it will correct itself, but try a reset.

daemon · 07-29-2005, 11:52 AM

Yes. I did do a reset. I actually noticed it before I ever took the stock box off in the first place. I just didn't really think about it too much at the time. It wasn't until I had to start tuning the short ram that it sort of clicked as to how to (at least one way) fix the issue.

STirish · 07-29-2005, 11:10 PM

Quote:

Originally Posted by daemon

Yes. I did do a reset. I actually noticed it before I ever took the stock box off in the first place. I just didn't really think about it too much at the time. It wasn't until I had to start tuning the short ram that it sort of clicked as to how to (at least one way) fix the issue.

That is an interesting idea. Since you calibrated the intake calibration map, what has the A/F Learning been doing?

daemon · 07-30-2005, 04:53 AM

I haven't touched the stock box calibration. But for the short ram I was playing with I had it adjusted so the learning was fine in closed loop and my AFR targets were getting hit at WOT in open loop. Too bad the ECU doesn't use a wideband to monitor WOT runs so it could auto-adjust the top end as easily as it does the bottom.

On the other hand, it is pretty hot here these days (highs in mid 90s) and I don't know if the ECU adds fuel for high IATs the way it pulls timing. If it does, then it would lean me out of my current values as winter approaches. If it doesn't, I'd be good to go.

07-29-2005, 08:05 AM	#1
daemon Professional STI Racer Car: 2004 STi Location: Florida Posts: 827 Join Date: Feb 2004 Trader Rating: (0)	Stock air box too rich for anyone else at WOT? Has anyone else noticed AFRs that are significantly richer than what is in the primary fuel map when using the stock air box? I had been playing with a short ram, but took it off last night due to insanely high and non-stop fluctations of IAT. When I first put it on I noticed that the loads I was hitting were >3. Then I noticed how rich I was running compared to the fuel map so I started tweaking the intake calibration so I was running about inline with the fuel map. And no surprise, my loads dropped under 3 once again since load is in part derived from how much air the MAF says is entering the system. By calibrating the intake I fixed the lie. Anyway, after putting the stock box back on, I noticed again, that even the stock box is running richer than the fuel map calls for. So it almost seems to me like the stock intake calibration is being a bit forgiving of the stock box and telling the system it is letting in more air than it really is. So I'm wondering if it just me, or is anyone else seeing their stock box running richer than they expected? If I adjust the stock box calibration, I'd bet my loads drop sub-3 again. This ad is not endorsed by this member. Please register or login to hide this ad.

07-29-2005, 08:13 AM	#2
jays05 Spec C Club Fav Mod: when it's not blown up Location: Upstate NY Posts: 1,594 Join Date: Nov 2004 Trader Rating: (0)	The stock narrowband O2 sensor is really inaccurate at anything besides 14.7 AFR. I target 11.4 AFR in the lower right hand corner of the fuel map and get 10.8-10.9 AFR on my LC-1 WB02. You also point out something that I noticed when I first put on my Injen CAI (before the MAF rescaling). Aftermarket intakes that flow more air than the stock airbox and fool the MAF sensor and lean the car out (which we all knew), but they also mess with the calculated engine Load which is used in just about all of the different maps. So you also end up with different AFR targets, timing, etc. MAF scaling is key with aftermarket intakes (besides the k&n typhoon and possibly others). After scaling mine the loads are back to normal. Last edited by jays05 : 07-29-2005 at 08:16 AM.

07-30-2005, 04:53 AM	#7
daemon Professional STI Racer Car: 2004 STi Location: Florida Posts: 827 Join Date: Feb 2004 Trader Rating: (0)	I haven't touched the stock box calibration. But for the short ram I was playing with I had it adjusted so the learning was fine in closed loop and my AFR targets were getting hit at WOT in open loop. Too bad the ECU doesn't use a wideband to monitor WOT runs so it could auto-adjust the top end as easily as it does the bottom. On the other hand, it is pretty hot here these days (highs in mid 90s) and I don't know if the ECU adds fuel for high IATs the way it pulls timing. If it does, then it would lean me out of my current values as winter approaches. If it doesn't, I'd be good to go. This ad is not endorsed by this member. Please register or login to hide this ad.

07-29-2005, 08:25 AM	#3
daemon Professional STI Racer Car: 2004 STi Location: Florida Posts: 827 Join Date: Feb 2004 Trader Rating: (0)	Except the stock O2 sensor isn't used at WOT (I'm using an LM-1 for tuning, FWIW). The ECU is pretty much guessing at how much fuel to put in at WOT, so maybe it is designed to guess with a bit of error on the rich side. However, if we aren't hitting our fuel points in the map, doesn't it make sense to scale the intake calibration so that we do start hitting the fuel map values? Otherwise what's the point in putting values of meaning in the fuel map.

07-29-2005, 11:52 AM	#5
daemon Professional STI Racer Car: 2004 STi Location: Florida Posts: 827 Join Date: Feb 2004 Trader Rating: (0)	Yes. I did do a reset. I actually noticed it before I ever took the stock box off in the first place. I just didn't really think about it too much at the time. It wasn't until I had to start tuning the short ram that it sort of clicked as to how to (at least one way) fix the issue.