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Discussion Starter #1
And I need some help interpreting the data.

Made a quick run out and came back. During the 3.5 gear run my max and min
values are below:

MAF:
max= 20.267 lb/min
min=0.418 lb/min

What's our MAFs max ability to measure airflow in lb/min?

TPS:
max=75.686%
min=0.000%

Ben Moses and I adjusted my TPS a month or so ago. Hmmm... anyone know what
voltage is 100% to the ECU?

IAT:
max=55.4 degrees F
min=32.0 degrees F

Temp was 20 degrees F outside at the time of the log.

Spark Adv:
max=63.5
min=0

I guess I need to look at the graph of spark advance to see if I am getting
retard under high load. This measures load as well, and got 0-100% load.
Load is a calculated value. What is the calculation? And would retard under
high load be show as some value less than 15 degrees? It does show 15
degrees of advance at idle btw.

Items I have no idea how to interpret are:

SHRT FT 1= Short term fuel trim-Bank 1
max=10.939 percent correction
min= -8.594

LONG FT 1=Long term fuel trim- Bank1
max=9.375 percent correction
min= -3.906

And my front O2 sensor stuff. Too long to type out really.

Any help with interpreting this stuff? My car running well???


Ben Davis
98 Sentra SE Turbo
with new toy he has no idea how to use



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Ben98SentraSE
98 Sentra SE TURBO
 

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That is a cool toy. I'll help where I can.

<font face="Verdana, Arial" size="2">And would retard under
high load be show as some value less than 15 degrees? </font>
Probably not. 15 degrees is just your base timing (idle, no load). At higher rpm you are running more advance. I dont remember how load changes the advance. SCC discussed this somewhere. I'll see if I can find it later.

<font face="Verdana, Arial" size="2">Items I have no idea how to interpret are:

SHRT FT 1= Short term fuel trim-Bank 1
max=10.939 percent correction
min= -8.594

LONG FT 1=Long term fuel trim- Bank1
max=9.375 percent correction
min= -3.906</font>
Short term fuel trim is the change in fuel required (from the expected value based on MAF voltage) to make the O2 sensor happy. Short term fuel trim will be reset next trip.

Long term fuel trim is what the computer has learned over time (based on O2 readings). Your base fuel maps are programed into the ecu. Say you have a long term fuel trim of +5%. Your MAF is reading 2.0 volts and the base program says to open the injectors for 20 milliseconds (completly making up numbers). The long term correction says you should open the injectors for 21 milliseconds instead of 20 ms. Then the O2 sensor gives feedback on the result for short term corrections.

The FSM talks about the correction factors. I'll look these up later and tell you whats in there. I've gotta go now.
 

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Can you change the reading on the maf and TPS to Volts? The maf is toped at 5.1v(I think) and the TPS is topped at 4.1v.
 

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Discussion Starter #4
No, there isn't. The software I use is on www.obd-2.com

Take a look at it yourself if you want. There is a link to download it from there.
 

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damn, all of that stuff is only 120 bux? I might have to get one.

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98 se-r w/ p/r cai, stillen header, courtesy exhaust, JUN flywheel, ACT clutch, NOS nitrous kit, eibach springs, kyb struts, st sways, cusco camber plates, f/r strut braces, lotsa bushings, and a bunch of other crap not really worth mentioning
 

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Discussion Starter #6
Got mine for $80 on a DSM list group buy


Actually you just get a reg code and a homemade cat 5 cable hooked to a OBD2 connector. Find an OBD2 connector and 4 pins to go in it and I'll give you the specs and you can make your own
 
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umm..where could i get something like that for a OBD-I system???

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1993 NX2000
with stuff.
 
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<font face="Verdana, Arial" size="2">Originally posted by Ben98SentraSE:
Got mine for $80 on a DSM list group buy


Actually you just get a reg code and a homemade cat 5 cable hooked to a OBD2 connector. Find an OBD2 connector and 4 pins to go in it and I'll give you the specs and you can make your own
</font>
I'm interested in where to find this stuff?
 

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Discussion Starter #10
I have no idea where you can get a make-your-own OBD2 connector. If you can find one somewhere you are set then
 

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The supply voltage to the TPS is 5 volts. I would assume that that is considered 100% by the ECU.
If that is true, 75% of 5 volts is only 3.75v. You did floor it, didn't you? You want WOT TPS voltage to be between 4.1 and 4.4v (82-88%, again thats assuming that 5v=100%). Can it display data real time? That way you could hook a DVM to your TPS and open the throttle and read the voltage and compare it to the % number from the data logger.

The Craftsman DVM that I bought on Monday didn't work! SOB! So now I have to make another trip to the mall.
 
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