Dandxj Posted March 1 Share Posted March 1 1990 4.0L AW4 About a year ago I did a basic tune (plugs,cap/rotor, wires) and a new NTK O2 sensor. Afterwards it seemed to run worse. Since the truck does not get driven daily I kinda accepted it. Recently I acquired a REM from a fellow CC member ( thanks eaglescout526 ). The REM showed the O2 sensor stuck at 3.1 V and the engine never entered closed loop. I reinstalled the old O2 sensor, a ceramic body BOSCH sensor. The REM now shows the O2 voltage swings and going to closed loop within a minute or two. I have searched for a MOPAR 53004245 sensor with no luck. The MOPAR sites either say "discontinued" or "currently unavailable". I did find one on a Canadian MOPAR site but they said they do not ship outside of Canada. If anyone has a source for the MOPAR sensor ( or an acceptable replacement ) please let me know. The NTK sensor is all metal and has the four wire to three wire connector. The old BOSCH has the ceramic body and is three wires the whole way. Looking here and on other forums it seems the new BOSCH are also all metal with the four wire to three wire connector. Thanks Link to comment Share on other sites More sharing options...
Pete M Posted March 1 Share Posted March 1 I would try searching that part number on ebay Link to comment Share on other sites More sharing options...
eaglescout526 Posted March 2 Share Posted March 2 You’re welcome!! Link to comment Share on other sites More sharing options...
cruiser54 Posted March 3 Share Posted March 3 ever checked the ground and power to the oxygen sensor? Without that it don't work. How about the resistance at the oxygen sensor with it unplugged? Between the red and black wires. Link to comment Share on other sites More sharing options...
pizzaman09 Posted March 3 Share Posted March 3 Is it possible that the NTK you purchased was a dud? I had originally purchased a Bosch for preventative maintenance. When I got my REM I found that it was very lazy causing the truck to swing back and forth between lean and rich over the course of a minute causing crap idle when lean. Based on this forums recommendation I purchased the NTK and it works phenomenally. The NTK is quick to respond and does a great job holding the AFR right near stoichiometric. Idle is perfect and power is the best it's ever been. I have found that one can damage O2 sensors with vibration. On another car I used an air chisel to remove exhaust flange studs and the vibration broke both O2 sensors. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 3 Share Posted March 3 ^^ All this can be verified first. Test the sensor for continuity and verify power and ground to the sensor. Link to comment Share on other sites More sharing options...
Dandxj Posted March 3 Author Share Posted March 3 After the REM pointed to the O2 sensor, power, ground and continuity of old sensor were checked. That lead me to put the old BOSCH sensor back in. Now the ECU is happy ( O2 voltage swings ) and the engine goes into closed loop. Since the NTK appears dead and BOSCH is of unknown age ( although currently working ) I was searching for new one. Link to comment Share on other sites More sharing options...
Gojira94 Posted March 4 Share Posted March 4 I purchased an NTK a while back through a Local Autozone, thinking I'd be good when it all comes together. The picture showed a ceramic body, got one with a metal body. Saw recent chatter about NTKs no longer being any good. I pulled it out of the box and poked my meter leads through the bag and got 4.7-4.8 ohms. Manuals call for 6, I think with 5-7 being acceptable. Great... So... theoretically, if there was a sensor out there that was known to reliably have a heater grid circuit resistance of 6 ohms with a 0-5V range output, it could be adapted. I think even a 4 wire could have its signal ground wire joined to the heater circuit ground, since there is a fixed resistor in the ECU behind the pin that receives signal voltage from the sensor. LSU 4.2 and 4.9 are out of the question, as typical universal 6-pin, 0-5V output "wideband" sensors require a standalone controller. I run an Innovate LC-2 controller in my 92 C1500. It has 2 output wires with a 0-5V signal and uses a relay (not included, you must install) to control the heater circuit and controller power. I'd like to think a 0-5V signal direct to the ECU would work but I don't know the signal voltage characteristics coming straight off the signal wire from the Renix O2 sensor. If the fixed resistor in the Renix ECU in some way shapes or regulates the incoming O2 signal for use as an input, I have no idea what the nature of that is. Wish I did. Link to comment Share on other sites More sharing options...
Ωhm Posted March 4 Share Posted March 4 11 minutes ago, Gojira94 said: I'd like to think a 0-5V signal direct to the ECU would work but I don't know the signal voltage characteristics coming straight off the signal wire from the Renix O2 sensor I'm under the impression both O2 Heater Circuit and O2 Signal Circuit share a common ground. Meaning ECU supplies 5vdc (pull down resistor) for Signal and Heater Relay supplies 12vdc for Heater. Maybe I'm missing something here. Link to comment Share on other sites More sharing options...
Gojira94 Posted March 4 Share Posted March 4 13 minutes ago, Ωhm said: I'm under the impression both O2 Heater Circuit and O2 Signal Circuit share a common ground. Meaning ECU supplies 5vdc (pull down resistor) for Signal and Heater Relay supplies 12vdc for Heater. Maybe I'm missing something here. That's the way I'm reading it for grounds, thanks for clearing it up on how the fixed resistor in the ECU works. I'm very familiar with GM stuff's "5V reference" but Renix is still a black box to me for the most part. So even a standalone wideband controller supplying a 0-5V signal would be out of the question. I recalled I ordered my sensor direct from NTK, not Autozone. I'm going to request product support and see where it goes. At least see if I can have a conversation with them about it. Wish me luck. Link to comment Share on other sites More sharing options...
Ωhm Posted March 4 Share Posted March 4 Check out NickinTime REM for Wideband O2. https://nickintimedesign.com/rem-wideband-converter/ Link to comment Share on other sites More sharing options...
Gojira94 Posted March 4 Share Posted March 4 15 minutes ago, Ωhm said: Check out NickinTime REM for Wideband O2. https://nickintimedesign.com/rem-wideband-converter/ Yeah, my LC-2 in my other truck can do one of its 2 outputs to 0-1V narrowband emulation for a factory ECU that uses a 0-1V signal. Or you can have 2x 0-5V signal wires (ostensibly one for a gauge and one for an ECU to use to control fuel trims in the 0-5V range). If the WB controller firmware is set properly for the fuel type and what voltage = 14.62-14.7 AFR then all should be good. I thought the pulldown resistor would somehow interfere with a direct 0-5V input, since the OE design does not generate its own voltage and relies on the ECU to provide it at the input pin. I'd love to have a REM but my timing is off with Nick's production, as he's just had a baby and stock of some of the stuff he needs to make the REM is in short supply (or was). Innovate LC-2 is a VERY nice controller, selling for $169 these days. I've sent a message to NGK/NTK support. If that goes nowhere I'll look into a standalone unit like the LC-2. But that's not a solution for everybody who just wants a plug in sensor that works like OE. Link to comment Share on other sites More sharing options...
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