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90 ecu and maf

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coop795

10+ Year Contributor
72
2
Aug 5, 2008
Meridian, Idaho
I am in need of a 90 tsi california ecu and maf to rent for a week, I will pay shipping both ways and a reasonable fee. It has to be a california spec ecu, no other will do. Please let me know if you have one so I can get my car smogged and back on the road. Thank you
 
Dont need to do it like that. The maf is the same in all years. There are two resistors on the ECU's that change if its for Federal of California and FWD and AWD Emmisions. Ill see if i can get the write up for you.

There are two resistors R129 and R130. Idk what combo you need to use though. Im still looking

Here you go

I decided to play a little more with the R129 and R130 config
resistor code, after Nick's help with it last week for my Australian
customer. The value in L0x55 reflects whether R129 is installed or
not, and L0x56 shows whether R130 is installed or not. The values of
L0x55 and L0x56 are loaded from a map at FB22, 2 bytes for each
combination of the 2 resistors. The resistors also determine which of
the addresses at FB2A-FB31 are used, which point to 4 different 12-
byte maps beginning at FBEC. The resistors also determine which
vehicle ID code comes up in the logger, from FB32-FB39.
I would think that most people would want to do what I was doing,
forcing Federal AWD mode, so thats what I'll mainly focus on:
In order, the 4 combinations at FB22 are:
1) 82 00 = R129=in R130=in, FED/FWD, L0x55=82h (130d), L0x56=00
2) 84 01 = R129=out R130=in, CA/FWD, L0x55=84h (132d), L0x56=01
3) 82 82 = R129=in R130=out,FED AWD,L0x55=82h(130d),L0x56=82h (130d)**
4) 84 83 = R129=out R130=out, CA/AWD, L0x55=84h(132d),L0x56=83h(131d)

So, the third combination is the one we want, 82 82. You can either
rewrite the suboutine at EA21-EA2F to just store those values to
L0x55 and L0x56 directly, or, like I've done, just change all 8 bytes
of the map at FB22 to 82 82 82 82 82 82 82 82. I also change all 8
bytes of FB2A to FC 04 FC 04 FC 04 FC 04 also, so that it always
loads the same 12-byte FED/AWD map from there too, no matter what
combination of resistors the customer's ECU has.
As a further explanation of what the code at EA21-EA2f is doing,
the status of the 2 resistors is read initally by 2 hardware bits, 0
and 1, of 0x7. I believe the logic is inverted, due to the fact that
the logic is normally held HIGH, unless a resistor is installed,
which pulls it LOW. So, when a resistor is installed, it results in
a "0" in that bit, not a "1". So, the actual bits are:
Bit 0 = R129 = "0" when R129 installed
Bit 1 = R130 = "0" when R130 installed
When read together, as two bytes, the combinations are:
00 = FED/FWD
01 = CA/FWD
02 = FED/AWD *****
03 = CA/AWD

I still need to look at the code at D792, that points to one of those
4 different 12-byte maps, to see what they do, but I haven't had much
time.
One more note: people, like me, that are working with the GVR-4 code
too, the combination we want is with BOTH resistors installed, so I
change all 8 bytes to 82 80 82 80 82 80 82 80, and FC 04 FC 04 FC 04
FC 04. And, of course, in BOTH cases, you can also substitute E0 22
for all 8 bytes at FB32, and the ECU will always read as a Federal
ECU on the logger, whatever that means.
Have fun with it!
Jeff O.
 
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