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.

It's not really any better. I can start it up cold and it jumps to high idle like it should. After a short time if stumbles and acts like it doesn't want to run properly. It won't die, but it acts like it wants to. Putting the ECU into mode 2, after it's warmed up, both lights come on. They will stay on for about 20 seconds and go off for 4 seconds then come back on. It continues to do that. The exhaust doesn't smell right. If I understand the manual right, that means it's between 5% lean and 5% rich. I don't think that it blinks enough to consider normal operation? Can anyone verify how the lights are suppose to blink for normal operation? The only thing I haven't done is to remove the injector clips one at a time and see if that does anything. As most of us know, you can't get to the inside bank to remove the clips without removing the plenum, making jumper harnesses and putting the plenum back on. At this point I think I need to try that? I don't really know what else to do.

I surfaced the manifold. Installed the gasket and the ring at the end of the manifold. Started it up, there was a leak. After a few choice words were said, the ring at the end of the manifold was leaking. So I get to go back to the parts store and buy the flange gasket I just returned. it's supposed to rain for the next 3 days. What's another few days with it being down?

The manifold is warped. I haven’t measured it, but it looks like around 1/8” or so. It’s at the front of the manifold. I don’t think it’s going to want to bend that much going back together. The middle and the back are flat. I have a belt sander but I can’t find any sanding belts that are the right size. If I can find the right size, it’s the wrong material. It’s going to take me for ever to make it flat with the belt I have now. I was wanting to get this finished this weekend. That’s not going to happen. I only had to drill and resize one hole. It was the very front. Thankfully it was the easier one to get to without having to get an extra long drill bit. We don’t have the corrosion out here compared to others. I can’t imagine having to deal with that. The O2 was a Bosch, I think. I made sure to keep the wires away from things.

The hose for the fuel pressure regulator has been changed. The new intake boot was actually nicer than I expected. It did fix the whistle. The problem still remains. I think I finally found out what the issue is. After putting on the new intake tube, it was still running rough. I reved the engine up by hand and noticed a pretty bad exhaust manifold leak on the passenger side. I had not heard the leak before. With hearing about all of the issues of studs breaking, I'm a bit worried. That and I have a bit over 300k, I'm not expecting things to go very well. The check engine light actually came on, O2 sensor. Since the O2 is brand new and with the exhaust leak, I'm pretty sure that's what caused the check engine light to come on. Do these manifold have a tendency to warp? I have a sander that will fit the manifold to flatten it out. It's just a long process making a cast manifold flat again.

When I removed the intake to look at the injectors and the line underneath, everything appeared to be good. I don't recall specifically looking at that line. The intake tube is whistling off and on. I'm going to address that first, if that doesn't fix it, on to other things.

The diy smoke machine didn't result in the intake tube showing a leak. The EGR BPV valve did leak. From what I have been able to find, that's normal with the engine off.

I may have caught a break. I drove the Pathfinder and was hearing a hissing noise. Pretty high pitched. It was coming from the intake tube. I could squeeze it and it would stop. Squeeze it a different way and it would start again. I have ordered a new intake tube. Hopefully it is decent quality. It's new but made in China. I am gathering things to make my own smoke machine just in case.

I have the manual saved. I'm pretty sure I checked that mode on the ECU. I can always try it again and see what happens.

I pulled the intake, nothing wrong as I suspected. A couple of the vacuum lines were showing signs of getting old, but nothing that was definite. I did replace the lines in question. There was no change to how it runs. The dizzy is tight. I don't have a timing light to verify what it's set at. I wasn't able to turn it by hand. I can buy a cheap one or rent one from the parts store.

Because the plugs are pretty white, I’m assuming a lean misfire. Especially with the little pops out the exhaust.