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2,148 Posts
Hey,
The afm screw mod is a great idea, but unfortunately is a little unsafe becuase you are telling the ecu there is less air, without compensating with more fuel, so it runs leaner than stock.
Originally I was planning to use an AFPR to jack up fuel pressure, then back out the afm screw so I could run 15 psi, with a stock afr. The afpr raises fuel pressure by increasing the preload of a spring on a diaphragm of the fpr, so I did just that with a stock FPR. I did this with a 3/8" drive extension and a hammer, pushing the centre of the top of the FPR down only .23 mm (measured with verniers). I backed the afm screw out all the way (~13 turns) and found a .23 mm fpr crush was needed to get back to stock afr's.
I did all the measurement with my wideband, and then took it for a rip afterward. Unfortunately I cannot load the afr curve from my laptop though(old pos). At 3500 and 5000 rpm its a hair below 12:1, and it dips to about 11:1 at 4000 and toward redline. This is without any electronic tuning.
Not all cars are the same, but if you were to do this, then reset your ecu, the ecu will adjust for any minor car to car variances. THis should be a fairly safe mod to do, as long as your fuel pump is up to par (the stock ct will hate you though).
BTW, I found one thread that discussed the idea.
Good luck!
The afm screw mod is a great idea, but unfortunately is a little unsafe becuase you are telling the ecu there is less air, without compensating with more fuel, so it runs leaner than stock.
Originally I was planning to use an AFPR to jack up fuel pressure, then back out the afm screw so I could run 15 psi, with a stock afr. The afpr raises fuel pressure by increasing the preload of a spring on a diaphragm of the fpr, so I did just that with a stock FPR. I did this with a 3/8" drive extension and a hammer, pushing the centre of the top of the FPR down only .23 mm (measured with verniers). I backed the afm screw out all the way (~13 turns) and found a .23 mm fpr crush was needed to get back to stock afr's.
I did all the measurement with my wideband, and then took it for a rip afterward. Unfortunately I cannot load the afr curve from my laptop though(old pos). At 3500 and 5000 rpm its a hair below 12:1, and it dips to about 11:1 at 4000 and toward redline. This is without any electronic tuning.
Not all cars are the same, but if you were to do this, then reset your ecu, the ecu will adjust for any minor car to car variances. THis should be a fairly safe mod to do, as long as your fuel pump is up to par (the stock ct will hate you though).
BTW, I found one thread that discussed the idea.
Good luck!
i Knew itd work! now, if you had an SAFC, you could tun out the rest of the richness to 12:1ish and get a little more power out of that thing. id like to see what the fuel pressure changes before and after.
