ECU's & Harnesses Differs With 02 Sensor Wiring!!!!!

[got2b240]

I have Definately Secured this Statement with several cars. I have been wondering why my car was running so rich and I managed to take apart and strip my whole harness to neaten up things a little bit and discovered this verry useful knowledge.

NOTE: Late model Blacktops (TYPE-X) use a different harness Layout then the two mentioned below. If you need a pinout for that harness please email me or post below.

ok here it goes:

Early Blacktop Harness' use a Brown/Yellow Stripe (pin 114) wire to give the Heated Oxygen Sensor a Ground/Internal Standpoint.

So the E5/E6 Ecu's (Early Blacktop Computer) is needed if you are using an Early Blacktop Harness!! Otherwise the Heated Oxygen Sensor will not complete the circuit and give a legitimate signal to the ECU (via pin 19)

Early Model Redtop Harness' use a black wire that is looped up by the Injectors and Iacv in the harness and shares a ground with them by a crimped union of ground wires that bolt to the Intake Manifold itself

So the E62/E63 Ecu's (Early Redtop Computer) is needed if you dont see any Brown/Yellow Stripe wire in your harness on pin 114 of the ECU Plug.

But you could use an E5/E6 Computer with a Redtop harness, because the harness is self-grounding.

So the verdict is that your Heated Oxygen Sensor WONT work if you have a Early Model Blacktop Harness and a E62/63 ECU. Because it doesnt have a ground to complete the circuit and send signal to the ecu.

The Heated Oxygen Sensor Plug comming from the harness if you put it facing you with the Hump (clip) on the top goes from left to right like this:

|Ground|..............|Signal Out|............|Power| ^ ............................^........................^(b/y or Blk) (White) (Differs)

You can test to see if your getting signal by letting the car warm up at idle and pop the hood. With the 02 Sensor Plugged in still, take your multimeter and set it in Volts DC and stick your red probe/lead in the middle wire through the back of the plug, you should be seeing somewhere between .3 to .9 (+/- a little bit) but no higher than 1 or no lower then 0.

When you rev the engine a little bit the voltage should bounce around more frequently (cycling voltage) within the specs I told you, this means its reading properly.

This will tell you if your 02 Sensor is sending proper signal out through the Middle (Thick White) wire. If its sending too HIGH, then you have an incompatible 02 sensor or its faulty. If you have none then you have your wires wrong...or possible faulty 02 sensor.

You can quickly test continuity in the 02 sensor itself by unplugging the sensor and probing the two outter prongs and by having your multimeter read in Ohms, you should see anywhere from 3-1,000 Ohms according to FSM.

I hope someone can give me some feedback if you read this. I am almost 100% sure about this because I have tested and tried this.

ALSO WHY WE RUN RICH?

Most of us have the 190 or 255 LPH walboro and it bumps up the fuel pressure at idle.... which is supposed to be 36 at idle with hose connected to the FPR......and if you unplug it it should read 44 accordingly to the FSM...

If you have a Fuel Pressure Gauge and notice it sits high (40 ish) at idle, you can also tag this on to the list of reasons why we run a little rich.

This can be avoided by re-setting your base fuel pressure with a Adjustable Fuel Pressure Regulator that can be purchased by any of our sponsors here at NICO or anywhere on the web (ebay,others)

Also the Scale for an oxygen sensor is :

closer to .0 is LEAN

closer to .9 is RICH

[slow s13]

My personal experience lines up with your findings, I got a early black top with a red top ecu. I already had an 02 gauge up and running on my KA and when I swaped motors, it didnt act at all like it should. The 02 sensor I recieved had a huge dent in it and I thought well thats why its bad. So I ordered one and also scored a E5 ecu on ebay. I installed them at the same time and of course my gauge started working as it should....now I know why.

Thanks for clearing up the differences between the models, I had always heard there was something but never new what it was.

Other than the ground thats the only difference? So if I supply the early E5 harness pin 114 ground I could run my red top ecu without damaging the O2? Its probly my imagination but I swear the car was faster with the red top ecu but it was probly just that first taste of turbo powa that made it seem faster hahaha.

[got2b240]

True the first taste is always a thrill then it settles down....but the passion never dies.

I have finally come to a conclusion here I am verry glad it helped you.

If my theory is correct then yes you should be able to......but I have never tried that.

What I find wierd is that when you try to test the brown/yellow at the harness on a e5/e6 ecu, it doesnt have continuity with ground!!?!? Maybe its a internal circuit that the ECU runs, or maybe its a human error on my part. For the rest I am 99.99% positive is true.

ALSO:

If our 02 sensor works, the higher fuel pressure is usually not a problem due to ECU correction taking place. So basically if we run rich due to no 02.....not only does the computer not know our possible AFR's, but it automatically compensates by running a richer map for safeguarding the engine's running cycle, and you can tack on the extra fuel pressure to that one . So if we run rich....we run REALLY RICH

Any Feedback?

[SpeedRacer1]

Heh, I knew about this slight difference between the redtop and early blacktop for awhile. I just figured nobody cared too much.

As for running rich, it is most related to the ECU telling the engine to run rich, not fuel pressure. The ECU tells the engine to run rich, when you disrupt the ECU signal with something like an SAFC the idle emissions decrease immensely. Also if you disconnect the O2 sensor, the engine will run much leaner at idle yet get incredibly rich at anything above idle. The decrease in idle emissions by disconnecting the O2 sensor should be enough to pass most states emissions test, however leaving it disconnected will cause one to fail the cruise test by reading way too high. Something like 6 times the legal limit by my states standards.

This info was gathered by an emissions testing machine.

[got2b240]

good info and thanks speedracer1