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Fuel cut? Or something else?

dsmkid

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Joined
Sep 27, 2011
Messages
61
Location
Denver, Co
Awesome, Got a palm pilot, now I just need the cable /ubbthreads/images/graemlins/smile.gif
 

Diego

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Joined
Dec 9, 2007
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2,132
Location
In a van down by the river, Iowa
I just ordered one from amazon the other day for like under $10 shipped. I just wish I know where my OG cable went
 

MuffinMan7580

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Joined
Aug 6, 2011
Messages
142
Location
Fort Bragg, NC
Or you can just build your own cable.

1N914 is a diode. They kind of act as a check valve, so that line you see on the diagram refers to a line on the diode. And then there is a resister (10k Ohm). You use a DB9 computer connector. The ALDL side is the OBD1 connector under your dash next to your fuse panel next to your left foot. You can buy everything at a Radio Shack.
 
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MuffinMan7580

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Aug 6, 2011
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142
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Fort Bragg, NC
Quoting turbowop:
Quoting dsmkid:
I even set the S-AFC to +25% across the board at hi-throttle and the issue still occurs.



Right there is a big problem. Adding that much fuel via an SAFC actually means you're adding 25% airflow to what the ECU sees. Once the ECU sees more airflow than it wants to with the factory eprom, BAM! fuel cut.

I don't think you fully understand exactly what an SAFC does.



He's running a 2g MAS with stock injectors, you have to compensate for the difference in signal. He has it right.
 

Brunoboy

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Apr 25, 2008
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2,880
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San Bruno,CA Home of SFO
It's not the correct way though. Make it easier toss some Evo injectors in.
-Shane
 

MuffinMan7580

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Aug 6, 2011
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Fort Bragg, NC
What's not correct about it? He changed the input signal to the ECU by added a 2g MAS, which reads roughly 25% less Hertz, and doesn't have the fuel injectors to compensate, so he added 25% to correct it.
 
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Brunoboy

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Apr 25, 2008
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San Bruno,CA Home of SFO
even by adding the correct amount to make it run ok, doesnt mean he should be doing so without a logger or anything to watch knock and timing......
 

turbowop

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Apr 29, 2001
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Yakima, WA
Quoting MuffinMan7580:


He's running a 2g MAS with stock injectors, you have to compensate for the difference in signal. He has it right.



By adding all that signal to the ECU, you bring it closer to the fuelcut threshold. I don't understand why this is so difficult for some of you guys to grasp, or why you want to argue with me about it. He asked why he was hitting fuelcut, I gave the answer. /ubbthreads/images/graemlins/crazy.gif Even if the 2gMaf reads less airflow to begin with, the car has airflow mods and is probably flowing enough to cause this issue, and adding signal just exacerbates it.
 
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MuffinMan7580

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Aug 6, 2011
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142
Location
Fort Bragg, NC
Yes, because running 14 PSI of boost(with a FMIC) is going to really be making a ton of knock. Especially with the ECU seeing the same reading with the 2g MAS that it would be reading with the 1g MAS. You can argue that he might be running out of fuel, and yes, he possibly is, but again, at 14 psi with a FMIC, you can probably get away with a 12:1 AFR with no knock. Answers like your last one are silly. It's similar to saying, "I don't want to turn the boost up from 20 psi on my 35r until I get onto the dyno, that way I know I'm making more power". People always state that you need a logger or a wideband to do anything, but I call BS. I've seen people make 350 on a street tune without a wideband. Then throw it on a dyno to make 2 pulls just to make sure timing is optimal.
 

MuffinMan7580

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Joined
Aug 6, 2011
Messages
142
Location
Fort Bragg, NC
Quoting turbowop:
By adding all that signal to the ECU, you bring it closer to the fuelcut threshold. I don't understand why this is so difficult for some of you guys to grasp, or why you want to argue with me about it. He asked why he was hitting fuelcut, I gave the answer. /ubbthreads/images/graemlins/crazy.gif Even if the 2gMaf reads less airflow to begin with, the car has airflow mods and is probably flowing enough to cause this issue, and adding signal just exacerbates it.



Agreed, that it's not going to put fuel cut in check. I'm curious as to why people are saying that adding the signal back in is the incorrect way to have his car setup. Yes larger injectors would be ideal, but his car doesn't have larger injectors, so until he does, or gets something else figured out, his tune is pretty close to correct. That is what I'm trying to get across.
 
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