Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Hey Everyone,
I have a 1991 Nissan D21 2wd 2.4L its running rich. I checked the O2 sensor with my lab scope and the O2 sensor was holding right at 900mv which is rich. I replaced the O2 sensor since it been a long time since it had been replaced and also done the tune up of the truck with the essentials cap, rotor, wires and plugs. also put in a new fuel pump because the screen on the pump had rotted off and was letting it pick up trash. So while I was that far into it I went ahead and changed the pump and screen and inline filter and the truck got new injectors because it packed them full of rust and trash from over the years. I checked the MAF and IAC with a known good wave form on my Vantage pro and they appear to be working. Truck doesn't have power trying to climb a hill its sounds like its loading up with fuel and bogging down. I pulled the plugs out and the were covered in black soot. These don't even have a hour runtime on them. Also swapped a coil from a known good truck still has the same issue. it smokes black out the exhaust when you crank it up and when you rev it up sitting there but it doesn't bog down till you get to a hill. any help would be greatly appreciated.
It's OBD1 only has the one O2 sensor it stays around 890 to 905mv is as high as I seen it get. I was thinking it should oscillate from lean to rich bit its not according to my vantage pro lab scope
only time I seen it go lean was right after you rev it and it goes leans for just a second then it goes back rich. I unplugged the coolant temp sensor earlier today and ran worse with it unplugged.
unfortunately Nissan didn't put a diagnostic connector on this model truck from what I was told and you can't get any live data from the ecm. only thing you can do is turn the screw on the ecm to get into self diagnostic mode and watch the flash codes and I done it like three times and I got a code 55 and Mitchell says that's no codes stored but it runs rich and stinks. it was so bad it had my other trucks cab smelling like that. it was parked right next to it it sitting outside and it would burn your eyes from being so rich. you can see the black soot coming out the exhaust pipe. I dropped the converter and its all black sooted up. i'm gonna replace it once I get it to stop running rich
Topic Author
