AFR too high; how much more fuel pressure is needed?

[Turboflash]

On my Cat (2017), stock fuel line was rubber fuel injection hose. When I added FPR and larger pump kit, I changed to Gates Barricade Fuel Injection hose (225 psi working pressure) just because I wanted to be SURE everything was the best it could be.
From looking at several TCats in my group with AEM AFR gages, all with TD FPR kits and PEFI Fuel pump kits, it seems with same FPR they don't all idle at same AFR. Don't understand why. There's one at 13.9 - 14.2 with about 47 psi fp. Mine is 12.4-12.6 with same FP. Doesn't make sense to me. Is there that much difference from gage to gage? How much difference could there be from one wide band O2 sensor to the next? We're all using Bosch LSU 4.9.

 

[Turboflash]

Looks like Sebastien added some notes on the tunes. Dont recall seeing this earlier this winter.
View attachment 167584

Agree 100% Justinator. I think that last statement has been added lately (within the last few months!). I spoke to Sebastien face-to-face at Haydays in MN and specifically asked him about using the 2.5" D&D Tech2 muffler (straight-thru unbaffled) I already had. He told me "It will be fine." Obviously NOT.
Me and my riding pals with PEFI tunes figured it all out last year and all is well now on Stage 3R Multimap.
If I did it over again, I would have installed the AFR gage from day 1. That would have told the story! Straight-thru/free-flowing 2.5" PM leans out AFR too much.

 

[blown apex]

I figured you'd be up there around 54 or so lbs. Bet the idle is a bit rich with really rich midrange and crusing...

so with my apex supercharged sled
i didnt want a big fuel pump cobbled in tank or externally mounted that i cant control idle richness
so to keep the idle from being over rich
i used a kenny bell fuel pump booster on the stock fuel pump set at 5 psi boost to turn on with a adjustable hobs switch
as boost came up fuel pressure went down below 35psi /now i added voltage till i kept 43psi steady at wot but it turns on and off at 5 psi boost
that fixed my wot lean afr and it has a adjustable switch you can turn up the fuel pump amps/volts to get more fuel from the stock pump
2006 and it still all works good with 6000 miles on this engine 14 psi boost 3 stock head gaskets stacked
i data log with a racepak udx dash fuel pressure/egt/wideband/parker knock box 5v signal to racepak/iat/boost
dont ask why i put this all on it
very expensive to not know whats going on with tuning engines
now i bought 2 new 2023 srx's thats why im looking at these forums
1st new sidewinder finally power steering

now i hope my new sidewinder with 270 tune is faster than my apex with 14 psi

 

[KnappAttack]

On my Cat (2017), stock fuel line was rubber fuel injection hose. When I added FPR and larger pump kit, I changed to Gates Barricade Fuel Injection hose (225 psi working pressure) just because I wanted to be SURE everything was the best it could be.
From looking at several TCats in my group with AEM AFR gages, all with TD FPR kits and PEFI Fuel pump kits, it seems with same FPR they don't all idle at same AFR. Don't understand why. There's one at 13.9 - 14.2 with about 47 psi fp. Mine is 12.4-12.6 with same FP. Doesn't make sense to me. Is there that much difference from gage to gage? How much difference could there be from one wide band O2 sensor to the next? We're all using Bosch LSU 4.9.

I have multiple sleds setup exactly the same, some idle at 12.0 and some idle at high 13's. All have identical setups in them. Craziest thing I've ever seen.

Something even crazier, you can increase the fuel pressure up, even go way up to 60 or even 70 lbs key on, you can just crank the regulator up bu y multiple turns and the idle AF doesn't go any richer. If you decrease the fuel pressure below the stock 44 lbs key on, the AF will go lean in a heartbeat, but increase it and nothing, it sits and idles exactly the same not fluctuating a bit or changing AF ratio whatsoever, but at midrange and WFO obviously it will richen up quite a bit like it should. I can go from 125% on the fuel multiplier to down into the 80% if you want to, but at idle, no change, someone tell me how that works.... The closed loop isn't supposed to work at idle, only when you get into track speed does the closed loop start working.

 

[sledding rocks]

On my Cat (2017), stock fuel line was rubber fuel injection hose. When I added FPR and larger pump kit, I changed to Gates Barricade Fuel Injection hose (225 psi working pressure) just because I wanted to be SURE everything was the best it could be.
From looking at several TCats in my group with AEM AFR gages, all with TD FPR kits and PEFI Fuel pump kits, it seems with same FPR they don't all idle at same AFR. Don't understand why. There's one at 13.9 - 14.2 with about 47 psi fp. Mine is 12.4-12.6 with same FP. Doesn't make sense to me. Is there that much difference from gage to gage? How much difference could there be from one wide band O2 sensor to the next? We're all using Bosch LSU 4.9.

i have experienced all of the above u have mentioned , but now i have up graded to the closed loop with fine tuning which puts my a/f exactly were i set it , 12.5 idle , 14.0 mid 12.1 wot , with my td fpr set at 48 psi

 

[max rolph]

you cannot set idlel on the maping of closed loop.... only low speed, mid cruise and wot. as Knapp said we have tryed everything to figure this out....dont get why the added pressure would not dictate more fuel being pushed through each pulse of injector and we know the auto tune isnt changing it at idle. ive changed my o2 sensor and still same read

 

[Turboflash]

I have multiple sleds setup exactly the same, some idle at 12.0 and some idle at high 13's. All have identical setups in them. Craziest thing I've ever seen.

Something even crazier, you can increase the fuel pressure up, even go way up to 60 or even 70 lbs key on, you can just crank the regulator up bu y multiple turns and the idle AF doesn't go any richer. If you decrease the fuel pressure below the stock 44 lbs key on, the AF will go lean in a heartbeat, but increase it and nothing, it sits and idles exactly the same not fluctuating a bit or changing AF ratio whatsoever, but at midrange and WFO obviously it will richen up quite a bit like it should. I can go from 125% on the fuel multiplier to down into the 80% if you want to, but at idle, no change, someone tell me how that works.... The closed loop isn't supposed to work at idle, only when you get into track speed does the closed loop start working.

I even tried 3 brand new FP gages (the exact one TD sends with their kit). Guess what? All 3 read differently. Biggest variation was about 3 psi. Even knowing that, when setting FP with the variation in mind, the idle AFR still wouldn't come into synch. Yes, when riding lower FP equalled leaner AFR.
I'm yet to understand what's going on with this. Someone please enlighten me.

 

[Turboflash]

I have multiple sleds setup exactly the same, some idle at 12.0 and some idle at high 13's. All have identical setups in them. Craziest thing I've ever seen.

Something even crazier, you can increase the fuel pressure up, even go way up to 60 or even 70 lbs key on, you can just crank the regulator up bu y multiple turns and the idle AF doesn't go any richer. If you decrease the fuel pressure below the stock 44 lbs key on, the AF will go lean in a heartbeat, but increase it and nothing, it sits and idles exactly the same not fluctuating a bit or changing AF ratio whatsoever, but at midrange and WFO obviously it will richen up quite a bit like it should. I can go from 125% on the fuel multiplier to down into the 80% if you want to, but at idle, no change, someone tell me how that works.... The closed loop isn't supposed to work at idle, only when you get into track speed does the closed loop start working.

BTW - yes my gage is vented to atmosphere per KnappAttack.

 

[sideshowBob]

I have multiple sleds setup exactly the same, some idle at 12.0 and some idle at high 13's. All have identical setups in them. Craziest thing I've ever seen.

Something even crazier, you can increase the fuel pressure up, even go way up to 60 or even 70 lbs key on, you can just crank the regulator up bu y multiple turns and the idle AF doesn't go any richer. If you decrease the fuel pressure below the stock 44 lbs key on, the AF will go lean in a heartbeat, but increase it and nothing, it sits and idles exactly the same not fluctuating a bit or changing AF ratio whatsoever, but at midrange and WFO obviously it will richen up quite a bit like it should. I can go from 125% on the fuel multiplier to down into the 80% if you want to, but at idle, no change, someone tell me how that works.... The closed loop isn't supposed to work at idle, only when you get into track speed does the closed loop start working.

Have you tried adjusting the TPS?

 

[NYTurbo]

I expect the ECU is controlling the idle speed by lettting in more or less air . Which I think is what is being said by sideshowbob above.

 

[Fleecer]

you cannot set idlel on the maping of closed loop.... only low speed, mid cruise and wot. as Knapp said we have tryed everything to figure this out....dont get why the added pressure would not dictate more fuel being pushed through each pulse of injector and we know the auto tune isnt changing it at idle. ive changed my o2 sensor and still same read

You are correct! Closed Loop only works from 5000 rpm and above.

 

[sideshowBob]

You are correct! Closed Loop only works from 5000 rpm and above.

Thanks to Mike Knapp and Yamamarc's help and tutoring, I have been data logging finally after having it it for three years but not using it!
I don't know how I ever got along not using it.
Anyway...
If you look at the snap shot of one of my logs you will see the "Closed loop Fuel Multiplier" is 95.2 at just over 3000 rpm which indicates to me the closed loop adjustment is working at that rpm and pulling almost 5% fuel from what the sled would normally provide which would be 100%.

 

[Turboflash]

I expect the ECU is controlling the idle speed by lettting in more or less air . Which I think is what is being said by sideshowbob above.

Agree. To my knowledge most modern systems the ECU uses IAC (idle air control) to control idle RPM when TPS is at base setting (throttle closed). Once the throttle position comes up, ECU uses throttle position along with many other sensors to determine proper timing, injection pulse width, boost, etc.
Stock 998 fuel injection doesn't have O2 feedback so there is no way for ECU to adjust AFR? That's the whole advantage of closed loop. When we're manually increasing fuel pressure, you'd think that should equal more fuel each time the injectors pulse, including at idle. But something else seems to be going on for AFR to remain constant? What?
Just thinking out loud. SSBob - How would adjusting TPS help? For that to work, it would have to be the case that the TPS voltage at base idle is not low enough so pulse width is a bit high? Again, not sure what's going on.
It's really not a problem per se because the sleds idle fine even with AFRs in the high 13's to 14. It does seem my sled with idle AFR at low 12s has better throttle response coming off idle.

 

[earthling]

Thanks to Mike Knapp and Yamamarc's help and tutoring, I have been data logging finally after having it it for three years but not using it!
I don't know how I ever got along not using it.
Anyway...
If you look at the snap shot of one of my logs you will see the "Closed loop Fuel Multiplier" is 95.2 at just over 3000 rpm which indicates to me the closed loop adjustment is working at that rpm and pulling almost 5% fuel from what the sled would normally provide which would be 100%.

View attachment 167596

Are the data logs available as CSV (raw data)?

 

[sideshowBob]

As the throttle is opened the TPS Voltage output increases My TPS voltage at idle is .7 volts at full throttle the voltage rises to 3.8.
I am not sure if increasing the voltage at idle would make the ECU think it needed to provide more fuel or less?
It may have no effect at all on AFRS..???