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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Installed a simple universal 4-wire 02 sensor on my 1992 camaro 305 TBI with 8746 ecm. I'll attach images of the harness i made and a diagram of how it is wired.
The car does go into closed loop status easier and stays in closed loop status. It does not make it go into closed loop sooner as the ecm does have a timer preset from what i can tell. Best of all doing a AMP draw test, it only used 0.60 to 0.70 amps on initial startup and slowly trickled down as it got warmer.
Wire colors 02 sensor side:
• Blue - Signal Wire to Ecm
• White - Signal ground wire to engine block or body
• Black 1 - Heater pos (+) or neg (-)
• Black 2 - Heater pos (+) or neg (-)
• Black wires are NOT polarity sensitive, use either one as pos (+) or neg (-)
Wire colors car side:
• Red - battery pos (+) 12v
• Black - body ground (-)
• Yellow - 12v ignition signal wire
Items used are as follows:
• Universal o2 sensor Denso part # 234-4209
• 4-wire pigtails by Grote, Male part # 84-9459, Female part # 84-9460
• Wire terminals by Grote, Male part # 84-2048, Female part # 84-2047
• Wire seals by Grote, part # 84-2002
• 18ga Yellow wire for 12v ignition wire
• 16ga or 18ga Red wire for battery 12v (16ga was used)
• 16ga or 18ga Black wire for ground (16ga was used)
• 12v relay 4-pin or 5-pin (5-pin was used, using only 4 pins)
• Relay pigtail standard ignition part # HP3810
• Wire terminals standard ignition part # CG7 (for relay harness wires)
• Wire ring terminal for ground
• Wire ring terminal for battery 12v positive
• Electric Tape
• Solder
• Solder Iron
• 1/4" Wire Loom
• Zip Ties Wiring diagram Denso universal 4-wire 02 sensor part # 234-4209 Almost complete harness New 02 harness complete with terminals and wire loom. 02 sensor for heater and signal ground are going to body ground on the left, 02 sensor relay in the middle, that fuse is factory i believe for the fan. O2 sensor installed in factory location O2 sensor side of pigtail. Car side of harness, with factory 02 wire plugged in (brown wire). Fan relay, this is a dummy relay for my Hayden fan Controller, it allows the fan controller to be ran from the factory car harness. Small yellow wire is 12v ignition, which where i ran my 12v signal wire to for the o2 relay. Solder joints have been fixed better than imaged once 02 relay signal was installed.
Last edited by Armored91Camaro; 12-14-2020 at 12:10 PM.
Reason: Added more information.
Better to find the ECMs 02 sensor ground, cut that one wire off the ground attached to the engine and connect the 02 signal ground directly to the ECM pin via the OEM signal ground wire. Did that on my G20 van when it still had a 299 and it also worked with the 7747 and later 7427.
The ecm ground is located on the engine block, the 3rd ground wire you see is the engine ground wire that connects directly to the battery. So far no issues, the car runs smoother on the interstate and is slightly more responsive. My BLMs are reading simular to what they where which to me means its working perfectly. One thing that does work better is reading higher rpm BLM past 3200, the ecm doesn't disconnect while cruising up through the rpms slowly. I haven't looked at any of the datalogs of full throttle to see if anything changes with the o2 sensor milivolts.
So far no issues, if ground becomes an issue in a later date then ill move it directly to the engine block cylinder head with the ecm o2 ground.
Another issue it fixed was a rough idle, then again that could because the sensor is also new, instead of having 30k miles.
Years ago, with my headers, yeah I need a better ground on my O2 sensor. I went the low-buck route and hose-clamped a braided ground strap, then took that to the back of the cylinder head to where the main chassis ground was.
It was an effective upgrade because my BLM's changed by a few points.
I'd imagine taking a dedicated ground lead directly to the O2 sensor ground wire on the ECM would probably be even more accurate.
Years ago, with my headers, yeah I need a better ground on my O2 sensor. I went the low-buck route and hose-clamped a braided ground strap, then took that to the back of the cylinder head to where the main chassis ground was.
It was an effective upgrade because my BLM's changed by a few points.
I'd imagine taking a dedicated ground lead directly to the O2 sensor ground wire on the ECM would probably be even more accurate.
Its far more accurate, after reading page after page on many o2 forums all over the web and learning the differences between, 1 -2 - 3 and 4 wire i decided the 4 wire, then after finding my ECM o2 ground location i decided to go the route i made.
Eventually i would like to do a wideband o2, just haven't talked myself into it yet.
I don't see what it could hurt, i mean single wire o2 is very old technology and only somewhat reliable. Better flowing exhaust of any kind can hinder it reaching proper operating temp to actually measure what it needs to measure.
12-14-2020, 08:34 AM
