EGR valve issues

DISVNVET

MEMBER
1994 MAZDA MX3
1.8L
V6
2WD
MANUAL
150,000 MILES

Due to smog problems (could not pass) decided to:
1. Decarb engine (used BG44K)
2. Removed Intake Manifold and cleaned all egr ports.
3. Removed Throttle Body and cleaned all carbon.
4. Changed EGR Valve: This is where the problems began. First of all the original was hard wired to the position sensor and vehicle harness. The EGR Valve has a removable position sensor connector. The original wires were cut to make a harness for making of a new harness that matched (?) The original three wire connection. The car runs great up to a point. At approximately 2800-3500 RPM I get a check engine light (2) The first OBD1 Code is 16 and the second 46. After the CEL comes on temporarily, I have a misfire.
5. At this point I am convinced that I did something wrong with the new harness and the presumption that the architecture of the Color Coding would be correct.
6. The problem now is the people that make the EGR Valve (intermodal) and the retail seller (SMP) cannot tell me which pins on the Sensor do what. They stated that this particular part is an OEM part. I can live with that but the manufacturer and the retailer should have some sense of how the EGR operates.
7. I am lost at this point and have high hopes someone has a guiding compass so I can resolve the issues.
8. Thanks in advance.

3 Replies

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

I have included in the diagrams down below for you the EGR system description, connector end views, resistance tests, and most importantly, engine performance wiring diagrams with the EGR wires highlighted for you. Look at the wires on the diagram, the color of each on is there. If you should have any other vehicle related questions, please feel free to ask It's what we do and why we are here.

Thanks,
Alex
2CarPros

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Friday, April 26th, 2019 AT 3:07 AM

DISVNVET

MEMBER
6 POSTS

Not completely lost now but still have questions. I looked at all the diagrams and you mentioned that the positions are marked but on the sensor on the EGR valve I see no markings. You addressed this from the connector side but I had to make a harness since the original was wired direct into the solenoid. Sp? Also, the images show two terminals. I gather from that the center terminal of the three is the common ground. Am I correct?

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Friday, April 26th, 2019 AT 10:22 AM

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello again,

That's right. The middle wire is the ground and it goes to G120 on the right side of the engine. If you look Engine Coolant Temperature sensor (ECT), and the Throttle Position Sensor (TPS) also splice into this wire, and the all connect to this ground. The signal return(-) wires of the TPS, EGR, and Volume Airflow Sensor (MAF) also splice together and run to pin #2I(That is two letter i) of the Power-train Control Module (PCM) connector. The white/orange stripe wire is the signal wire(+) going to the PCM.
Please let us know if you have any other questions. We're here to help.

Thanks,
Alex
2CarPros

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Friday, April 26th, 2019 AT 9:07 PM