Hey, thanks for the reply.mdmellott wrote: ↑Mon May 18, 2020 12:07 pmI'm not familiar with any of these ECU configuration differences but before I started chasing anything like that, I would first check the one and only adjustable component in the system to be sure it isn't clocked to one extreme or the other. The TPS is easy enough check and adjust for its proper setting. After that, there is an IACV relearn procedure you can easily do to be sure it hasn't lost its mind, so to speak.
That's what I thought but it measures to spec. 20-24 Ohm is the range... I measure 22. On all 4. Perfect.Buzzman wrote: ↑Mon May 18, 2020 7:22 pm18 year old Pathfinder with original IACV?
I wouldn't think twice about it, having gone through this problem a few years ago:
stop troubleshooting and just replace the IACV, period.
When these things are on the edge of failure, they will give you the symptoms you are describing.
Don't wait until it fails completely and then blows the ECU.
Just change it out.
Exactly.
Hey, nope, not on. I fixed a bunch of stuff before (FPR, Fuel-Damper, Leak at Oil cooler, etc)... Like I said, I'm doing car stuff for 18 years (usually high performance tho).Buzzman wrote: ↑Thu May 21, 2020 8:08 pmExactly.
Like I said, it's 18 years old, and when it finally fails for good, it will take out the ECM.
To Matce: You can continue troubleshooting this problem with your meter and stuff, but at the end of the day, replacing the IACV is the way to go.
If nothing else, it will give the owner peace of mind knowing he doesn't have a ticking time bomb in there.
Just make sure you do a relearn afterwards.
As an aside, I'm a little surprised it isn't throwing a code.
The check engine light is not on for sure?
Thanks bud, I'll take a closer look, but a revision would certainly make sense!mdmellott wrote: ↑Fri May 22, 2020 5:38 pmI got curious about this and then I got stumped as well, regarding the ECU wiring to the IACV. I have the same ECU number MEC14-345 C1 you have and the same year Pathfinder. I looked at the wire colors on my IACV and where they land at my ECU. Neither my wire colors or my ECU pinouts match the wiring diagram, with the exception of the yellow wire at pin 8 on the white connector block in the large ECU multiple junction connector. As for the pur/grn and gry/yel wires the diagram indicates at pins 6 and 17, I don't even see those wire colors anywhere in the ECU connector but I guess it's not relevant because those colors are not on my IACV either. Instead, the wire colors I have to the IACV are pur/blu, gry/blu, yel, and gry at ECU pin locations 3, 7, 8, and 30 respectively, plus the 2 voltage source red wires. There have been ECU revisions (different Nissan purchase part numbers) so I can only speculate that the official wiring diagrams did not change when Nissan changed component wire colors and ECU connector wire configurations in their part revisions. I did not open up my ECU to look at that MOSFET chip at IC17 like you did but I suspect you are seeing a revision upgrade with the NEC MOSFET instead of the Sanken MOSFET you expected to see. All the burned out ones I have seen online are the Sanken STA509A chips. I looked up the datasheets for both Sanken STA509A and NEC UPA1560H chips and found that the circuits are not exactly the same but do look the same functionally. The electrical characteristics of the NEC chip indicates that it holds up to higher loads than the Sanken chip. Of course, none of this sorts out the idle issue with the '02 you are working on but if your IACV has the same wire colors as mine then you can at least now confirm the continuity of the wires in the harness, assuming you see the same pinouts and wire colors I have found in mine. I did come across a posting from a user with a idle issue as you described and he found no electrical issues at all but fixed his problem by cleaning off an accumulation of gunk that built up on the IACV valve seat that inhibited proper air flow even though the valve motor was working properly. It's worth taking a look at since that would be a simple fix. Good luck with your diagnosis.
Ya, I'm still around.
Well, 18 years of Canadian weather has finally taken a death grip on the old girl.