Pics of new FMIC = scary afr's
07-26-2008, 01:40 PM
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Pics of new FMIC = scary afr's
Just finished installing my new fmic and BOV.
works great, no leaks, car pulls stronger, but, at the same 5psi, the thing is ******* lean now!
before the IC i could do 5/6 with afr's below 12.0:1
I still need to lower the boost, but from what i see, i'm lucky if I can get away with 4psi. it's going up to 13.0:1. all 4th gear pulls were the same... too lean!
running the vortech with 12.1 disc, 1.8 tan tops, and stock fuel pump.
i need to buy a afpr, a begi or so, quickly!
but at 4psi, it actually feels pretty much like 6.
works great, no leaks, car pulls stronger, but, at the same 5psi, the thing is ******* lean now!
before the IC i could do 5/6 with afr's below 12.0:1
I still need to lower the boost, but from what i see, i'm lucky if I can get away with 4psi. it's going up to 13.0:1. all 4th gear pulls were the same... too lean!
running the vortech with 12.1 disc, 1.8 tan tops, and stock fuel pump.
i need to buy a afpr, a begi or so, quickly!
but at 4psi, it actually feels pretty much like 6.
Last edited by mx5dude69; 07-26-2008 at 01:42 PM. Reason: forgot pics
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07-26-2008, 04:55 PM
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well, lots of people think 12.0 is the absolute min acceptable AFR.
2nd, just buy megasquirt. You have an intercooler which means you're a man now. Time to step up.
2nd, just buy megasquirt. You have an intercooler which means you're a man now. Time to step up.
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07-26-2008, 09:56 PM
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sorry about no pics of the IC. by the time i got the camera, i had the front grill mounted, so it really doesnt show in the photos. :(
it's a starion 2inch in/out by the way. only problem was to fabricate the mounts... i had to use a zip tie to clear the belt from one of the pipes. except for that, cant complain.
thx for your replies, so I need both the AFPR and a Wallbro.
hmm.. i thought i could get away with the stock fuel pump up to 8 psi.
but ok, thx for the tip, i'll order one also. any recommendations?
i'm very suprised i cant do more than 4 psi with the IC. it's a bit more effective than i thought. I mean, even after lowering to 4 pounds, i still get 12.5/12.6 where before i did 11.0 at 5 pounds. i have read a lot of people can get away with a lot more on the stock pump and stock injectors. i guess this euro version must have really different fuel maps!
last question:
if this was an air leak after the AFM, the extra air not accounted by the AFM, would result in a leaner mixture, because obviously if it doesnt know about it, cant send more fuel. if my understanding is correct, this is only true under vacuum, where the leak would actually suck air in. While in boost, any leaks in the pipes, being under positive pressure, would result in the opposite, richer mixture, because air would be expelled trough the leak, but the AFM wouldnt know about it, as it was measured before the leak, and sends enough fuel for the amount measured at the afm, correct?
it's a starion 2inch in/out by the way. only problem was to fabricate the mounts... i had to use a zip tie to clear the belt from one of the pipes. except for that, cant complain.
thx for your replies, so I need both the AFPR and a Wallbro.
hmm.. i thought i could get away with the stock fuel pump up to 8 psi.
but ok, thx for the tip, i'll order one also. any recommendations?
i'm very suprised i cant do more than 4 psi with the IC. it's a bit more effective than i thought. I mean, even after lowering to 4 pounds, i still get 12.5/12.6 where before i did 11.0 at 5 pounds. i have read a lot of people can get away with a lot more on the stock pump and stock injectors. i guess this euro version must have really different fuel maps!
last question:
if this was an air leak after the AFM, the extra air not accounted by the AFM, would result in a leaner mixture, because obviously if it doesnt know about it, cant send more fuel. if my understanding is correct, this is only true under vacuum, where the leak would actually suck air in. While in boost, any leaks in the pipes, being under positive pressure, would result in the opposite, richer mixture, because air would be expelled trough the leak, but the AFM wouldnt know about it, as it was measured before the leak, and sends enough fuel for the amount measured at the afm, correct?
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07-31-2008, 09:00 AM
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in the post below, Brain says:
"i assume you're rocking the FMU, so if boost leaks, at idle the vacuum will be lower, therefore more fuel pressure, therefore rich. in boost, the fmu doesn't clamp down on the return line, therefore less fuel pressure, therefore lean."
https://www.miataturbo.net/forum/showthread.php?t=19049
I see it idles at 14.7 and under vacuum I see it bouncing from 13.8 to 15.5.
When i floor it, building up boost, the first 1/2 psi, goes around mid 13's.
if I keep pushing it, around 3/4psi @ aprox 5krpms, it actually recovers and drops to 11.8 AFRs. So in high rpms with more pressure, it deliveres enough fuel.
( i opened the wastegate to the max with the annoying rattle)
this effectively proves there is no leak, just a plain simple case of IC efficiency and my Fuel Pump is not able to deliver enough pressure at low boost?
already bought and I am now waiting on the adjustable FPR and Wallbro255. hope it works.
"i assume you're rocking the FMU, so if boost leaks, at idle the vacuum will be lower, therefore more fuel pressure, therefore rich. in boost, the fmu doesn't clamp down on the return line, therefore less fuel pressure, therefore lean."
https://www.miataturbo.net/forum/showthread.php?t=19049
I see it idles at 14.7 and under vacuum I see it bouncing from 13.8 to 15.5.
When i floor it, building up boost, the first 1/2 psi, goes around mid 13's.
if I keep pushing it, around 3/4psi @ aprox 5krpms, it actually recovers and drops to 11.8 AFRs. So in high rpms with more pressure, it deliveres enough fuel.
( i opened the wastegate to the max with the annoying rattle)
this effectively proves there is no leak, just a plain simple case of IC efficiency and my Fuel Pump is not able to deliver enough pressure at low boost?
already bought and I am now waiting on the adjustable FPR and Wallbro255. hope it works.
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07-31-2008, 10:52 AM
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you're smart alright. ok, so this means i just need a adjustable FPR and ditch the stock one. I dont have a leak, and my Fuel Pump can deliver enough fuel when the vortech actually gets enough manifold pressure to start doing its job. the problem is spooling is too fast for the vortech to keep up with it. at low manifold pressure say 1 or 2pounds, it just cannot dump enough fuel with the IC cooling the air.
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