stinky Posted December 20, 2004 Share Posted December 20, 2004 I'm wiring in a chipped na ecu into a 280zxt and have hit a bit of a snag. I'm just wondering if any of you guys have any experience with this or might have some specific ideas about this problem. I'm tired and I dont want to retype everything so here is a paste.... With an NA ecu in the 280 the af guage will read .3v with no O2 sensor. That is to say the .3v is coming out of the ecu at pin 24. Now with the o2 sensor connected, the guage will swing back and forth with the mixture but it never goes below .3v on the guage. I’ve verified the outputs with a voltmeter so I know its not the guage. Now if I plug in my buddies turbo ecu everything is great. The meter goes full lean and full rich and it acts as it should. I would say that this is all caused by the ecu but it makes no sense because I can plug the na ecu in to my 300zx (which is using the identical sensor) and it reads as it should. So anyway I’m stumped. I’m going to have to check the wiring on my 300 to see if anything is obviously different. The only codes I get on the ecu when on the 280 is fuel pump (I’m not using pin 108 and fuel temp sensor (not used or required). It’s got to be something to do with the wiring. Any ideas? Quote Link to comment Share on other sites More sharing options...
yo2001 Posted December 20, 2004 Share Posted December 20, 2004 the 02 signal suppose to move around on Z31 ECU. that means it's working correctly. Quote Link to comment Share on other sites More sharing options...
stinky Posted December 20, 2004 Author Share Posted December 20, 2004 I'm aware of that. My problem is that with the sensor disconnected the ecu still has .3v coming from pin 24 (should be input pin from o2 sensor). With the o2 sensor plugged in it does sweep back and forth but it never goes below .3v which i know is not correct because I'm watching my AFR on my wideband and it goes extremely lean. With the turbo ecu connected all is well. Quote Link to comment Share on other sites More sharing options...
Afshin Posted December 20, 2004 Share Posted December 20, 2004 Interesting, I just connected my voltmeter to the wire going to my O2 sensor (after disconnecting it from the O2 sensor) and it also reads a steady 0.3v when the ignition is on (0v with the ignition off). Once the car runs, I get proper closed loop operation with my AFR gauge fluctuating back and forth as you do. My car has an rechiped (courtesy of Bernard) 88 na 300zx ecu. I don’t have time to play with the car for a few weeks, but this is what I know regarding the 300zx O2 wiring, it’s a 3 wire sensor as you know: -Black shielded wire is the voltage output signal (pin 24) -There is a blue ignition + signal wire -Third wire, which by default should be another ground for the heating element which comes from pin 115 (yellow wire) on the ecu to the sensor (it also goes to the 300zx fuel pressure regulator module). My best guess is that you need to ground pin 115 to complete the circuit. You should however first test and make sure that 115 is indeed a ground on your 300zx by testing it at the O2 connector, before grounding it from the ecu in the 280. Keep us posted to the outcome. Quote Link to comment Share on other sites More sharing options...
stinky Posted December 21, 2004 Author Share Posted December 21, 2004 Interesting....So when your car goes in to closed loop does the voltage fluctuate as it should including going below .3v or does it always stay above .3v like mine does? Also, I remember looking real quick and on my Z31 there is no wire in for pin 115. Quote Link to comment Share on other sites More sharing options...
AnTmanS130T Posted December 22, 2004 Share Posted December 22, 2004 Anyone have anything else to add? I don't know if Stinky has figured it out or not yet but if anyone else has any info or suggestions post up! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.