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· Over Medicated
2,804 Posts
The 2 wires that we cut were for the #1 and #2 oxygen sensors. We tied B48(OX1) into B47(OX2) This eliminated the need to have both front and rear OX sensors on the exhaust manifold, rear sensor now supplies both signals. As for the MAF conversion it is fairly straight forward as long as you can understand the Toyota service manuals. I'll do my best to expalin it though.

There are 5 wires on the OBDII MAF, you will only use 4 of them(Black w/Red not used).
1. Black/Red - 9-14v Power (not used)
2. Yellow/Red - VG signal from B66
3. P/L - THA signal from B45
4. Brown/Black - Ground E1
5. Brown - E2

There are 5 wires on the OBD1 MAF
1. Brown/ Black - Ground E2
2. P/L - THA signal from B45
3. LG/B - Karmon signal from B66
4. L/R - VCC signal from B41
5. Brown - Ground E1

The only difference is the #4 wire on the OBD1 plug. This signal needs to be gotten from the TPS sensor #4 wire VCC signal.
OK so here is the overall way it connects:

OBDII #5 - OBDI #5
OBDII #4 - OBDI #1
OBDII #3 - OBDI #2
OBDII #2 - OBDI #3
OBDII #1 - Not Used

OBDI #4 - TPS #4

I know this may be confusing but if you have a service manual it really helps.

As for your other questions. Yes a OBD1 auto ecu will work. The open loop thing I am not sure about however. You will need a MKIII chip for your VPC and make sure your resister is in the correct position.

Disclaimer: I am not responsible if you fuck up your car trying to do this conversion!

· Over Medicated
2,804 Posts
If you are already using both O2s I would leave it alone then. As for the resistor I am guessing that you will have to place the resistor in different pins.

· Over Medicated
2,804 Posts
kirkMKIV said:

I converted my car to OBD1 from just looking at his and my car runs flawlessly! you will install the VPC resistor on the same wire colors... dont touch the MAF plug if you are going OBD1/OBD2 and have a VPC... just run the resistor between 2 + 3
Glad to hear it is running good now.

Now there is going to be this big run on OBDI NA ecu's. Everyone will start asking $300 -$400 for them... :) By the way I've got 2 OBDI 5speed ecu's for sale :D
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