Tuning XFI with dual nozzle alky

[GN Junkie]

Hey Guys,

Been fiddling with the ole XFI and I'm having issues trying to smooth out the 02 correction roller coaster associated with full spray out of my dual nozzle setup (spraying 100% meth) Once the map hits about 15psi the AFR drops into the mid 9s and correction maxes to -10.2% AFR beings to rise all the way to mid high 11s which I understand is pretty lean for a dual nozzle setup. My question is should I allow the correction to pull more than 10% fuel or will that make the "seesaw" correction effect even worse? Am I correct to lower my target AFR to 10.5 within the higher map levels to help prevent leaning out at higher rpm/map levels?

I have my tune and logs here would anybody be willing to take a peek? Shoot me your email!


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[Razor]

What system you have that puts full spray at 15PSI?

 

[Reggie West]

Yours. It was set up like that.

Yes it should be at the factory setting of 8psi.

 

[GN Junkie]

I was under the impression that the initial turn on is 8psi before progressing to full spray which is a green light about 15 psi am I incorrect? It is your system Julio, just had it tested at the bates nut farm show I wanna say it made 140psi no leaks.


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[GN Junkie]

Good to hear from you Reggie, still trying to get this thing figured out. Heading down to Qualcomm 1/8th mile tomorrow for some test and tune so I'm hoping to get some advice first.


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[bison]

How much time does it sit at 9:1? Is it for a second or .05 second? You can alleviate rich spikes a few different ways.

 

[Razor]

The green led doesn't mean full spray, that just means the pump has made pressure over 50 psi
Some ways to alleviate is to do a fee things
1 is to have the system purged so the computer doesn't have to start the corrections

2 is to keep correction limits tighter as it's building boost like +-5 like from 4-5K rpm

And get correction dialed in in high gear then work on the transition to high gear
It's hard to get correction in the VE table squared away as the up and down is happening
Way I do it is till into the throttle to build boost up and bring things up slow
Once that is squared away I can worry about getting things squared away when the pedal is punched

 

[GN Junkie]

How much time does it sit at 9:1? Is it for a second or .05 second? You can alleviate rich spikes a few different ways.

I have my logging set up for 20fps it's dipping into the 9s (lowest 9.75) for about 1 second before going the other way as high as 11.5 at the top of first gear at 6450 rpm (isn't that a pretty high rpm?)


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[GN Junkie]

The green led doesn't mean full spray, that just means the pump has made pressure over 50 psi
Some ways to alleviate is to do a fee things
1 is to have the system purged so the computer doesn't have to start the corrections

2 is to keep correction limits tighter as it's building boost like +-5 like from 4-5K rpm

And get correction dialed in in high gear then work on the transition to high gear
It's hard to get correction in the VE table squared away as the up and down is happening
Way I do it is till into the throttle to build boost up and bring things up slow
Once that is squared away I can worry about getting things squared away when the pedal is punched

Wow ok that makes sense, full spray volume wise would be dictated by the blue gain knob on the controller then? Mine's set to 5.5 currently.

Not sure what you mean about purging the system?

My correction limits are -10 +20 within that rpm window so that would be something to look at. If I lowered the negative correction to -5 the engine would be even more rich without adjustments to the VE table correct? Not even adjusting the target AFR table would help in that instance because correction would be limited to 5%

Honestly I'm just overwhelmed by the VE table itself, there are so many damn boxes haha. Making the cell increases/decreases smooth and linear is hard for me. I change one section and I get paranoid that the rest is too far away.


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[GN Junkie]

If the rpm exceeds what I have setup on my VE table does the xfi use the closest fuel cell for that rpm/map? As you can see in the picture my rpm is exceeding 6000 in first gear and off the map entirely


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[bison]

If the rpm exceeds what I have setup on my VE table does the xfi use the closest fuel cell for that rpm/map? As you can see in the picture my rpm is exceeding 6000 in first gear and off the map entirely


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I'd approach it adding more rows of cells around flash stall and I'd also likely reduce the amount of correction in certain cells during ramp in and get the ve as close as possible to prevent the long spike. I don't see the need to be anywhere near 6000rpm unless you are making enough power to get that high in 3rd gear. Maybe you need to switch or dual in your governor and vb. XFI will just use the cell it's in if rpm and or boost goes over the tables numbers. I'd consider some of the following additionally not necessarily all of them or necessarily at the same time:
Go to a single nozzle
Use smaller nozzles if staying with 2
Use a 3.5 bar MAP sensor
Turn the gain down

If course the ve tabel will need adjustment after anyone of these is done. The scaling on the tables should be more spread out between flash stall and the highest rpm in :rd gear imo. This will give you more resolution in those cells and more room to fine tune the boost/rpm fueling. Keep in mind the timing table will change and needs to be looked at also. If you're going lean out the back it's likely a delivery or ve issue. Or possibly the learning in those cells is off and the ve number is way off. Doesn't seem like it based on the numbers visible though.. Check actual voltage too



BPE2013@hotmail.com

 

[GN Junkie]

Bison I emailed you my gct and matching log, I'm using xfi open loop boost control only running 19-23 psi at this point (seems to have some creep) so single nozzle might be a better fit for me at my novice state.


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[GN Junkie]

109 stroker 235ci w/ girdle
champion aluminum heads
solid lifter cam unknown specs
precision 6766 dbb
96lb injectors
torque converter unknown


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[GN Junkie]

Do you guys think my ramp up timing is too aggressive? It did pull 3 deg at about 220kpa 4300rpm

If I'm adjusting the VE table in the ramp up area do I trim from the exact cells where the correction is maxed at -10 or do I need to work on the cells just before that occurs. In other words is the XFI that exact or do you need to anticipate the fuel change before it even happens?


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[bison]

Your timing table needs a lot of work. You have too much timing up top for 93/alky imo. It should never be a straight number across either. Have you verified your timing is accurate?


BPE2013@hotmail.com

 

[pacecarta]

way aggressive on the spool
im around 22.5 degrees where you are highlighted

 

[GN Junkie]

Your timing table needs a lot of work. You have too much timing up top for 93/alky imo. It should never be a straight number across either. Have you verified your timing is accurate?


BPE2013@hotmail.com

I have not verified timing, putting that on the to do list. By never be a straight number across you're saying timing should not be duplicated scaling up the rpms? So even at wot higher up on the MAP timing should slowly decrease with rpm? I'm running 91 w/ alky so my timing is way out of whack then

Does anyone have an example of what a timing table should look like for a 91 alky setup?


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