RF600

I figured I would start over and check the TPS. I didn't really check it very good the first time. I was able to get the TPS to read. The manual says it should go up to 9 ohms resistance. The best I could bet was 7.3 ohms.

Thank you for the follow up. Mine looks like yours does in the pic. I haven't tried to put 12v to it and see what happens. The injectors ohm test within spec. I know that doesn't mean much. I wouldn't think the injectors would cause the up and down when holding the engine speed around 2K. I would think a sensor is malfunctioning. Something like the MAF or TPS acting up?

If you have the spare time to do that, I would appreciate it. I don't really know why it's running as poorly as it does. I agree, it doesn't make sense. Fresh tune up, no vacuum leaks, no codes, not really anything points to why it runs like it does. Since I haven't really haven't much with the injectors, I guess they might be worth looking into?

The plate on the inside has about a 40 degree open to close. It's about half way open currently. It operates freely. No binding, no signs of any soot or anything else. Would you expect the idle to suffer with it stuck half way? Most of the time when I start it cold it will jump up to high idle, but drops pretty quickly. If it doesn't go to high idle, it will struggle to idle properly.

The last time I pulled the plugs they were all white. Not wet. So lean fuel mixture and hot cylinder temps. The iac seems to be operating properly. I'm leaning towards the pulse air valve, or whatever it's called. It ohm's out good. I pulled it apart to look and see what is in there. Since I can't get a picture that will fit under the 64kb, I will try and explain it. There is a plate inside that is spring loaded. The plate has a slot that will open or close depending on the coolant temp, my assumption because the coolant line runs through a plate that is mounted to the plenum, then this valve is mounted to that. I tried putting it in the freezer and the plate didn't move. I tried heating it up and the plate didn't move. At this point I believe that this pulse valve is not operating like I think it should. The plate is stuck on the almost closed position. I assume when it's hot the plate is supposed to be in the open position, allowing air to pass through it. I'm half tempted to make it so the valve is always open to see what happens. I'm guessing at this point. I don't really have any other explanation of what could be happening. No vacuum leaks. I smoked the system.

AI says the iac valve is the likely issue. By now I can get the plenum off fairly quickly. lol. I guess that’s what I will check or replace next. In reality I can’t really complain. I have 305k miles on it and I have really not done anything besides regular maintenance. I will report back after I get to that.

I haven't driven it that much. The times I did drive it, I didn't notice the rpm issue. I would have to drive it again and pay more attention to things. I didn't think to use AI as possible help. At this point it isn't going to hurt.

The old distributor was doing the same thing

I cranked it as far as it would go until it hit something and stopped.

Well the distributor didn't fix the issue. Not sure if I mentioned this prior, when holding the RPM's around 2k, it will stay there for a short time, then it will drop about 500 RPM's for a moment, then go back up to what it was before. My tach doesn't work so I'm guessing at the RPM's.

I have an extra distributor that I marked core. I have had it so long I forget why I marked it that way. I figured I would try and put that one in and see if the issue goes away. The issue went away. I couldn’t get it any closer than 17 degrees. That’s within the range the manual gives. I am relieved to know that it should be the distributor. I will get an another one and cross my fingers that it fixes the problem. I will report back after the new one is installed.

Yes. It is in spec

Thank you.

I was doing the test at idle. Maybe that's why it was doing what it was? I started it up today and it didn't do the high cold idle. It went to running rough. The exhaust smells bad. That tells me the mixture is off. I did the mode 2 test again and ran the engine around 2k. I didn't count exactly the light interval, but it was blinking like it should. Mode 3 gives me a code 55. No surprise there. I remember back when I first got my pathfinder there was a weird stutter around 2k rpm's. It turned out the cam sensor was acting up. New dizzy fixed the issue. I suppose the cam sensor could be acting up and causing the issue. I have not pulled the dizzy and checked to see if the injectors pulse like they are supposed to. The timing is good. I checked it. I do have another dizzy that I believe is good. I can swap that over and see what happens. I like having an older vehicle, but having an OBD2 vehicle would make this process a whole lot easier.

I would appreciate it. I haven't checked the injectors yet as I have stated before. The fuel mileage isn't down, so I don't think they are an issue. I suppose it's possible that the cam sensor is acting up. I guess I need to buy a timing light.