Help with settings after 2g MAF in 1g

[imdrax]

So trust me I've spent HOURS researching and there are just a couple things beyond my reach here. Mods are in my profile. We're having some issues getting our fuel set up. We have base fuel @ 38 psi w/ vac hose off and the MBC set at 13psi.
After installing the 580cc's and 2g maf at the same time I went ahead and tried the recommended settings of -10 across on my AFC. NO WAY. The car was super lean. after getting my fuel trims in line I ended up with my AFC correction being nearly +15 across on the lo-throttle and in order to get rid of knock on the high settings were at +17 to +22, any lower and knock comes in and FAST, any higher and we get major hesitation. This happens at nearly every boost level. I'm tuning on knock, not O2 but my o2 readings NEVER go above .91v no matter how rich we get. The o2's are around .85-.87v all the time. I've also considered rich knock and tried running my afc in all negative, we started at -10 across and ended up getting up to 35 counts of knock. Base timing is at 5 degrees and there aren't any boost leaks. I'm considering a few things later:
1. up fuel pressure to 43 and drop my afc settings??
2. putting timing at 3 degrees
3. backing out the screw on bottom of maf
4. we'll be at the track tomorrow and will try throwing in some 110 to see if we can lean it out some.

The biggest thing is that after HOURS and literally HOURS of browsing threads it just seems WAYYYY out of the norm to be running my afc settings this high in order to get rid of my knock. Any help or thoughts or anything before tomorrow would be greatly appreciated because I really want to try and get some solid track runs in.

 

[SonySlave]

I did the 2G MAS install a few months ago and I was having a lot of the same issues you are having. I had PTE 680cc injectors, Walbro 255HP, AFPR, 2G MAS, and S-AFC1. With my PTE 5031E @ 26psi spikes falling to 21-22psi on 92oct pump gas, AFPR @ 43psi, I had to lean out my high settings to about -13% across the board just to get a 10.0-10.2AFR. That is crazy rich as you know, but if I leaned out the AFC anymore, there would be too much timing and I'd get knock. So I turned the CAS down to about 3* BTDC, still got knock. Turned it down to 0* TDC, got rid of all knock. It pulled really hard, but I was fouling plugs from being too rich, so I lowered my AFPR to about 34-35psi and at the same -13% lean, I was up to right around 11.0AFR, much better. You really shouldn't ever need to modify a 2G MAS, whether it be the honeycombs or adjustment screw.

Really your options here are:

1. Get an EPROM ECU and Keydiver chip
2. Get an EPROM ECU and DSMLink

or

3. Use your AFPR to tune your base pressure so that you don't have to lean or richen the S-AFC very much. Make some WOT pulls, then once you get your AFRs inline, then use the CAS to advance or retard your base timing to tune for no knock. But, don't retard it too much or you will severly hurt your idle, so you really have to find a good medium with the CAS, AFPR, and S-AFC. Don't be too worried about upping the AFPR to as much as 50-55psi base, it will help A LOT! Some say you will trash your injector seals, but I haven't had a single issue in the past and when I had my base at 50psi.

I know I've said a lot and I hope you understand it, but if you don't, say so, and we'll try to help!

 

[JayRolla]

I also have the same issue. Im running 2g pistons with 550's and a 2g maf. I had to set the timing too about zero degrees to get rid of knock at only 17psi. Im about to install a maf translator and 1150's with my safc. Then some e85 and the timing wont be an issue.

 

[imdrax]

Well we tried setting base FP to 43psi and still with the mbc at only 13psi we were getting knock. I had to up the settings on the afc to +22 in order to tune out the knock but then again the hesitation came back. The car will pull decently at the current boost setting with no hesitation if I lean it out a touch but I get anywhere from 5-10 counts of knock in order to get it this way. Tomorrow I will try lowering the base timing to 3 or 0 degrees at the track to see how things go. I plan on running with 50/50 mix 91/110 and starting the boost at 17psi on the current settings with 3 degrees timing and FP at 45psi. Anyone have any other suggestions other than that? One more question, I can't seem to find a definitive answer on what exactly the MMCD program's timing numbers are, in addition to base timing or just plain advance?

 

[imdrax]

UPDATE:

Well we just got back from the track. Ended up using 50/50 mix 91/100 because we wanted to stay unleaded. Set the base timing to 4 degrees, FP to 43, and boost at 15, Afc was set to +20 across on high still. The car ran pig rich and sputtered down the track to a dismal 15.8. 2nd run we set the AFC down to around +10 across and upped the boost to 18, managed a 14.6 but we were knocking fairly bad throughout the rpm band with anywhere from 7-15 counts. Due to knock our timing got pulled from 20 degrees at 5800 rpm after a nice curve, down to 14 by red line ending at 103.1% DC, 13 counts knock, .85v o2 with our DC hovering around 100% throughout the entire rpm range. I can't seem to figure out whats causing us to be maxing these injectors out at only 18psi on RACE FUEL. The only things i can think of are that the fuel pump isn't flowing correctly or the injectors were running are not clean/and or flowing right( Both of which came with the car not purchased by me) Any ideas??

 

[JayRolla]

I had this exact issue. I was running 20+ fuel and my 550's where seeing 90% IDC's. Its because you are running WAY rich. When I had the safc set at +15 accross I went to my buddy to have him through in his wbo2. The car pegged rich on the wbo2, and after we retuned to 11.1 afr we where at about +8 on the safc.

Car pulled harder than ever but we still see knock at 15psi and 3* base. I had to pull all the timing out to get rid of knock and still have 3-5 counts. I think still because of the timing. My knock would hit right when boost is full then slowly drop. Timing is too high in the lower rpms.

Im about to through in a maf-t, 1150's, 255lph fp and e85. That way the timing wont be an issue anymore. Pump gas sucks.

 

[imdrax]

Sounds about right. The thing thats funny is there is this teeny tiny fine line between stuttering rich and knocking lean that is less than 1% setting on the afc. Weird. Last thing were going to do is pull the pump to check it out and replace the fuel filter before we send the injectors off to be cleaned and flowed.