Fooling The Computer
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From: Kodiak AK
Fooling The Computer
Ok I have been thinking.....yes freaked me out too.
We as PSD modifiers place a pop off valve or needle valve in the map line to fool the computer that the boost is not going over 22psi. I thought the computer needs to know what the boost psi is to regulate the amount of fuel going through the injectors. Why doesn't Jody or a programmer change the map limit so the computer doesnt defuel. Or why can't someone come up with a new sensor that reports 30 psi instead of 22. Is there something I am missing?
We as PSD modifiers place a pop off valve or needle valve in the map line to fool the computer that the boost is not going over 22psi. I thought the computer needs to know what the boost psi is to regulate the amount of fuel going through the injectors. Why doesn't Jody or a programmer change the map limit so the computer doesnt defuel. Or why can't someone come up with a new sensor that reports 30 psi instead of 22. Is there something I am missing?
Lead Driver
Joined: Oct 2004
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From: Columbia, MO
I've asked Jody about this before. I think it has something to do with what they do and do not have control over. Like, the the de-fuel limit can't be changed. It may be a table that they don't have access to.
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From: Middle Tennessee
Originally Posted by jtharvey
I've asked Jody about this before. I think it has something to do with what they do and do not have control over. Like, the the de-fuel limit can't be changed. It may be a table that they don't have access to.
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I think it is a moot point. My guess is, above a certain amount of boost and at WOT, the PCM is telling the truck to dump as much fuel into the cylinders as possible. It's like if you are hot, so you go turn the thermostat down, but the AC is already running--yes, the AC knows you want it colder now, but it isn't going to change how much cold air you get.
Does this sound reasonable?
Does this sound reasonable?
Post Fiend
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From: Middle Tennessee
Well sort of, consider the top speed eliminator. If this can be eliminated, I would think the other garbage can be eliminated to a safety point. I say it is all programming, so change the program. I have been accused of oversimpying things though, and if I could solve this riddle, I would be selling chips/tunes. Since I cannot, I am here right now asking about it.
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I may not have been clear enough. I think that even if the truck realized it were generating 30lbs of boost, it would not change anything because it was already dispensing the maximum amount of fuel possible. Where this could be worthwhile is with aftermarket injectors, dual HPOP, etc...
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From: Kodiak AK
So what is the point of making more boost by keeping the wastegate closed if you can't get any more fuel?
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Post Fiend
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From: Middle Tennessee
Originally Posted by YellerMax
I may not have been clear enough. I think that even if the truck realized it were generating 30lbs of boost, it would not change anything because it was already dispensing the maximum amount of fuel possible. Where this could be worthwhile is with aftermarket injectors, dual HPOP, etc...
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Butt-Head
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From: Reed Point, MT
Here's my solution for the SES light and overboost code:
Ground the signal wire (middle one) coming out of the MAP sensor. I've seen it done on numerous trucks. My brother's 99 is that way, I did it to my 95, and it was done on my 01 when I bought it. It doesn't create a driveability problem, I have NEVER seen the SES light come on with it connected, and it certainly didn't hurt my mileage as I get nearly 20 MPG at 70 MPH either way.
Ground the signal wire (middle one) coming out of the MAP sensor. I've seen it done on numerous trucks. My brother's 99 is that way, I did it to my 95, and it was done on my 01 when I bought it. It doesn't create a driveability problem, I have NEVER seen the SES light come on with it connected, and it certainly didn't hurt my mileage as I get nearly 20 MPG at 70 MPH either way.
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From: Reed Point, MT
Couldn't tell you right now, Jeremy. I haven't put the scanner on my truck since I got it a year and a half ago. Never did scan the 95.
I do know that the MAP sensor output is a frequency...not a voltage. So there's no current or anything. I have to drive the truck to work tomorrow anyway so I will throw the Snappy on there and see what my data says.
I do know that the MAP sensor output is a frequency...not a voltage. So there's no current or anything. I have to drive the truck to work tomorrow anyway so I will throw the Snappy on there and see what my data says.
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From: Cheyenne, WY
The point is: the computer is fueling to the max at 23psi, same as it will at 30+ psi with a boost fooler.
It would be worthless and a waste of time to communicate any more boost to the PCM.
The problem isn't the PCM anyway, the PCM takes what information it is fed from the map sensor via resistance.
The electronic solution is the zenor diode mod in the line. Comes with all Banks kits. It's a 120K resistor. That changes the max resistance the MAP sensor is able to communicate to the PCM and problem solved.
It would be insane to try to rewrite the entire program for this one issue. It is a massive undertaking even to write a performance program.
It would be worthless and a waste of time to communicate any more boost to the PCM.
The problem isn't the PCM anyway, the PCM takes what information it is fed from the map sensor via resistance.
The electronic solution is the zenor diode mod in the line. Comes with all Banks kits. It's a 120K resistor. That changes the max resistance the MAP sensor is able to communicate to the PCM and problem solved.
It would be insane to try to rewrite the entire program for this one issue. It is a massive undertaking even to write a performance program.
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From: Kodiak AK
Originally Posted by GREGROB
The point is: the computer is fueling to the max at 23psi, same as it will at 30+ psi with a boost fooler.
It would be worthless and a waste of time to communicate any more boost to the PCM.
The problem isn't the PCM anyway, the PCM takes what information it is fed from the map sensor via resistance.
The electronic solution is the zenor diode mod in the line. Comes with all Banks kits. It's a 120K resistor. That changes the max resistance the MAP sensor is able to communicate to the PCM and problem solved.
It would be insane to try to rewrite the entire program for this one issue. It is a massive undertaking even to write a performance program.
It would be worthless and a waste of time to communicate any more boost to the PCM.
The problem isn't the PCM anyway, the PCM takes what information it is fed from the map sensor via resistance.
The electronic solution is the zenor diode mod in the line. Comes with all Banks kits. It's a 120K resistor. That changes the max resistance the MAP sensor is able to communicate to the PCM and problem solved.
It would be insane to try to rewrite the entire program for this one issue. It is a massive undertaking even to write a performance program.
Thanks
Laughing Gas
Joined: Jan 2006
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From: Gig Em, Tx
Originally Posted by GREGROB
The electronic solution is the zenor diode mod in the line. Comes with all Banks kits. It's a 120K resistor.
Sounds like a resistor in the circuit would be the proper course of action.
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