da3883ek

Hi everyone, new to the forum. I know this is an old topic but I figured it may help some people out there. This post is for those who have an OBD1 engine in an OBD2 car and need to clear the CEL's to pass smog.

Before reading this, know that I am not implying to use these bypasses as a permanent solution. These are just a few tricks to get your CEL's cleared to pass emissions.

Recently I bought a 96 DX hatch running a B16A with a JDM P30 ecu, which both are ODB1. Problem is though, you can't show up at the emissions site with an ODB1 ecu running in a ODB2 car. So here is what I did to clear my CEL's:

=USDM 96-97 Del Sol ecu (P30-A01 or A02) (ODB2a)
=piezo transducer
=o2 simulator

I bought these 3 things before starting the bypasses. The P30-A02 ecu that I used came from a USDM 97 Del Sol. Its a rare ecu, but if you can get your hands on one do it because I hear it can save some headaches. Also, one nice thing about this ecu is that it will plug in directly to your ODB2a (96-98) wire harness..so no conversion harness needed. Another nice thing is that it does not look for a fuel tank pressure sensor. After plugging it in to my wire harness and starting the vehicle, I noticed 3 CEL's that popped up.
The first was for the CKF sensor, which did not come equipped on the B16A. The second was for the secondary heated o2 sensor, which was not on the vehicle when I bought it. The last was for the knock sensor, which was broken and the person who swapped the engine in cut the connector off for it. In order to clear these codes, you have to trick the ecu into thinking that all the sensors are there and working.

CKF sensor bypass:


The CKF sensor is located in the oil pump, and the B16A is not equipped with this oil pump. You can either install an oil pump equipped with the CKF sensor, or you bypass it with some simple wiring.

For the CKF sensor bypass, I followed the instructions on this post: http://ff-squad.com/wp/?p=309 It's pretty simple to do and took me less than 10 minutes to finish. Basically, you are taking the CKF sensor wires and tapping into the CYP sensor wires' signal to trick the ecu into thinking that the CKF sensor is providing a signal.

Secondary o2 sensor bypass


This bypass is done by using an o2 sensor simulator, which sends a variable signal to the ecu. This will make the ecu think that there is an actual secondary o2 sensor installed and working correctly. The secondary o2 sensor is located in the rear of the cat or in the pipe behind it. On my DX, there is a high-flow cat with no secondary o2 sensor installed on it. You can either install a second o2 sensor and wire it in, or you can buy an o2 simulator and wire it directly to the ecu.

The secondary o2 simulator I used can be found here: http://www.ubertechnics.com/o2_simulator_2.5.aspx. It costs about $50 dollars and is not to difficult to install. I have mine mounted by my ecu for the time being. The are 6 terminals on the simulator to wire up and are from left to right as follows:

+12V | SIG | REF | GRD | HTR2 | HTR1

Here is a diagram of how I wired up the o2 simulator:

Refer to this link for an ODB2a ecu pinout: http://technet.ff-squad.com/wiring.obd2a.htm The actual sensor has 4 wires connected to it. 2 wires are used for the signal, and the other 2 wires are used for the heater part of it. Remove the oem wires from pins D13, D14, and A5 as you will be wiring the SIG, REF, and HTR2 wires from the simulator directly to the ecu connectors. Cap of the 3 pulled wires that were pulled from the harness, as these are not needed. As far as the A11 pin, leave that connected, as this is a power source wire that needs to be left connected to the ecu to run power into the engine bay. Splice the +12V and HTR1 wires from the simulator into this wire coming out of the A11 pin of the ecu connector. The last wire to hook up is the GRD wire to the body chassis. The simulator will now send signals to the ecu tricking it into thinking there is a secondary o2 sensor installed in your cat.

Knock sensor bypass


I followed the instuctions using this link: https://honda-tech.com/forums/forced-induction-16/knock-sensor-bypass-methods-part-numbers-1181854/

This bypass is done by using a piezo transducer, which can be bought at radio shack for around $2.00. To my understanding, this transducer turns vibrations into very low voltage outputs. By attaching it to the fuel rail, it will vibrate and produce low voltage outputs to the ecu making the ecu think that the voltage is coming from a working knock sensor.

First, locate the ecu pin D6 on the harness connector, then pull it out from the connector and cap it off (refer again to the ecu pinout diagram http://technet.ff-squad.com/wiring.obd2a.htm Next, run the positive wire (red) on the transducer through the fire wall and into the D6 pin on the harness connector. Run the ground wire (black) to a good ground in the engine bay. After the wires are all run, attach the transducer to your fuel rail. I used electrical tape, since its only temporary. Just remember to "loosely" tape the transducer to the fuel rail to ensure that it vibrates enough to produce voltage. I have heard that 2 transducers may have to be used in some cases due to the fact that one alone didn't produce enough voltage, but I only needed to use one. Again, this is only a temporary fix just to bypass emissions, I advise that you install a working knock sensor in your block as a permanent solution.

I have been driving the vehicle now for 75 miles, and no CEL's have popped up yet. After 100 miles have been driven, I will hook up my scanner to make sure that all monitors have cycled properly and the vehicles ecu can be ready for the emissions testing. (After reseting an ecu, the vehicle must be driven for at least 100 miles in order for emissions to be able to read).

I hope this helps some people and I will report back in a few days to let you know the results of the smog test.

da3883ek

Took my car to emissions yesterday with 200 miles driven since the ecu swap and passed.