Recent content by seva.zaikov


  1. seva.zaikov

    1997 4.0L runs rich

    I finally managed to go to the dealership with the truck. They thought originally it is bad wiring somewhere, but later they tested the PCM and it was the culprit. So, I got unlucky :) Now it runs smooth with proper mpg. Thanks for all the advice!
  2. seva.zaikov

    1997 4.0L runs rich

    Finally tested the actual O2 sensor connector. I used the downstream sensor (others were too much hassle to reach with a multimeter). Voltage was fluctuating, max I saw was 8V, average was around 2V. I also tried to test the continuity by measuring resistance, but no luck. So I wanted to find...
  3. seva.zaikov

    1997 4.0L runs rich

    Giving it more thought, the main issue is that all of them throw heater circuit malfunction. Since I replaced all the sensors, I don't blame them. If I understand wiring correctly, it goes from the PCM to the fuse and then to the sensors. Sensors are good, and the same for the fuse, so it...
  4. seva.zaikov

    1997 4.0L runs rich

    Just checked all the fuses under the hood (including the one which services all O2 sensors). All of them were good. The way I tested them was to put 20V mode in my multimeter, put the negative one to the ground (I used the frame and negative side of the battery) and connect to the fuse with the...
  5. seva.zaikov

    1997 4.0L runs rich

    Hi, I checked the voltage using the link above, by reading it from OBDII codes. I looked at all of them (all 3), and they actually all show steady 0 (not a single fluctuation). Assuming this data is correct, and the fact that I replaced O2 sensors recently, I guess the culprit is somewhere...
  6. seva.zaikov

    1997 4.0L runs rich

    Thanks for the suggestion, sounds reasonable. I've never tested the wiring before, so I might ask some dumb questions. First of all, do I check only truck's connectors, or sensor itself, or both? Another question is how to test. If I understand correctly, to test the ground, I need to measure...
  7. seva.zaikov

    1997 4.0L runs rich

    Alright, so I finally worked on the truck today. Things I've done: - cleaned the MAF sensor (looked fine actually) - replaced the third O2 sensor, which is after the cat converter (mostly for the piece of mind) - replaced spark plugs & wires (incredibly tight spaces!) - replaced a thermostat -...
  8. seva.zaikov

    1997 4.0L runs rich

    Yeah, I think I will do it, thanks – I think nothing except thermostat affects the temperature, so it definitely should at least bring it up to ~190. However, after I've read that the loop is stuck open due to error codes, I am not so sure whether it might solve it. In my model there are only 3...
  9. seva.zaikov

    1997 4.0L runs rich

    Hi everybody, I recently bought my first truck, and it is a pretty old Ranger, 1997 2wd manual 5spd 4.0L engine with 155k miles on it. The truck runs strong, transmission works nice, there seems to be no leaks, and the price was good. But it runs rich and gets about ~12mpg on the highway, ~10...


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