Here's the underside of the air filter housing and there's a part with two wires no longer connected. Anyone know what that was doing? Anyone hazard a guess where they go? Soldered into the two metal inserts or perhaps to the two screws? No idea.

My guess would be intake air temp (IAT). Probably supposed to egress the housing through a grommet.

Check out 16580 in this diagram:

Hmmmm this is an odd one.

The wires broke off from the center piece of the IAT sensor, in between the two phillips head screws that mount the IAT to the air cleaner housing. In the picture you posted, I can just make out where they were once attached. It doesn't look to be fixable. Nissan part number 22630-95L00 is what you need to replace that broken IAT sensor. RockAuto has 12mo and 36mo warranty aftermarket replacements for $11 and $39 or you can pick up genuine OEM for around $53 from online retailers like Nissan Parts Deal. You kind of get what you pay for or are willing to pay.

Curious point: There was no mention about your check engine light being on with respect to this post regarding the broken wires from the IAT sensor or the previous post regarding the broken wire from the O2 sensor. The CEL should have flagged each of these. If it didn't, your CEL light bulb is probably burned out.

If you're getting a black tailpipe when the truck goes gutless, the IAT could also be responsible for that. An open IAT reads as "Alaska", so the ECM will dial the mixture way rich.

Hey thanks MD! Just ordered the parts now from Nissan along with some wingnuts and stoppers that were missing. We'll see if this goes to helping the gutless problem!

No CEL light in this truck. I see battery and oil pressure but that's it.
https://imgur.com/a/H2l0c0w

Thanks for the tip Vstar but with the half rotted out muffler I can't see any smoke when she goes gutless. (muffler on list)

Your CEL should come on when you put the ignition in the On position and then turn off when you start the engine, if there are no DTC codes stored. On your instrument cluster, I think the check engine light is right above the battery icon. There is no screen printed icon for the CEL like there is for the battery, oil, brake, etc. Nobody wants to see that dreaded engine icon with the word "check" written across it unless there is actually an issue. If it does not light up when you turn the key to On, then the bulb for the CEL is burned out.

I'll double check that but I'm pretty sure there wasn't a bulb assigned for any area that didn't have a printed icon. I pulled the cluster a couple times to fix the speedo needle and install LEDs for the old bulbs. I've got the smaller LEDs to put into those sections so I'll give her another look for sure.

Ok so the new IAT sensor is in. I haven't pulled the cluster display to reinsert new LEDs to see if a CEL light is there or not but son of a gun does she run like a bag of poop now.

I chokes at around 2000 rpm best guess as I haven't a display for that and I'm pulling on the throttle at the body. So it as I mentioned she chokes and drops down and revs up chokes drops down and revs up etc when you pull the throttle wide open. Idle runs rough. I've been monkeying with a screw that's sits between the throttle arm that I'm pulling on and the throttle body...doesn't seem to fix anything....likely made things worse.

Will research but she's undrivable right now as is.

I hope you get this sorted out. You absolutely do have a check engine light. However, it may not be as simple as replacing the bulb by just pulling it out and plugging in a new one. The CEL on my '02 Pathfinder, for instance, is a surface mounted bulb on a circuit board which is soldered in place. Your disconnected O2 sensor and maybe the IAT sensor would have turned on your CEL and stored a DTC in your ECM. It seems obviously, the CEL is burned out but the stored DTC's will still be there. Having replaced the O2 sensor and IAT sensor, those trouble codes may have gone away but any other issues for which a DTC would be triggered will be there. A generic scan tool is an essential item in my tool box. The one I have is more than a code reader but not a technically expensive one either. With all the work you are doing on your D21, I recommend purchasing at least a basic diagnostic generic scan tool. The one I purchased paid for itself the first time I used it. The Foxwell NT301 ODB2 scanner is what I use. https://www.amazon.com/FOXWELL-NT301-Pr ... 00UJV3E12/ What I'm not sure of is whether your vehicle is ODB1 or ODB2. There is also a manual mode code retrieval procedure you can follow to get stored trouble codes from your ECM, without any scan tool. If your D21 is anything like my old '91 Pathfinder, you will find the ECM under the front passenger seat.

Hey MD yeah it would seem that with putting in sensors that were long since unplugged (that IAT plug was definately unplugged some years ago and my thought it the system went wonky and someone figured out just to unplug the unit) I'm going to go ahead and take a guess now for the sake of s*** and giggles and say it's a non-functioning ...something. After I do code reading, I'll unplug that sensor so at least I can use the truck in the meantime.

I had pulled the bench seat from the truck and scrubbed down the interior so I noted that box but didn't know what the heck it was at the time. I'll need to yank the bench again likely based on what I saw yesterday. The code lights are on the side and they're a simple procedure to read. Simply turn the key to 'on' and read the red blinks followed by the green blinks. Leave the scanner in mode 4 or 5 and turn the vehicle off and it resets...I maybe a little off on the details there and will need to go over them one more time before I proceed. I do have a scanner as well for my 2001 Mercedes but I don't think it'll work on this older computer box.

I'll be getting about 20 feet of 5/32 vacuum line to replace everything in there. If the code reader can't give me a defined location like a purge valve or something of the kind it could be the wire harness at the injectors as noted on this sticky http://www.infamousnissan.com/forum/sho ... hp?t=25332

Plugging in the IAT should result in leaning the mixture, so if it will only run unplugged, then it sounds like it wants to run very rich. Could very well be a restricted-injector or fuel pressure problem.

Solved. The connector to the throttle position sensor wasn't making full contact due to the work in the area.
After disconnecting the IAT sensor and believing I had mucked up the idle position with that horizontal setting screw, I went to work trying to slowly turn that screw back and forth for an hour, revving up the throttle to get it back to normal and getting no where at all....just at the point I was going to move to something else I looked and saw the throttle position sensor connector didn't look like it was all the way engaged. Once I pushed that in, the engine went back to normal.

I've plugged the IAT sensor back in and she's running normal outside of maybe a notch away from where that idle screw should be at, I've tuned it by ear and I'm no mechanic...but I do sound for a living so...

There's a marginal increase in performance but when I drop to fourth on these mountain highway passes, I still loose acceleration with the foot to the floor. She's not exhibiting any symptoms of blow by, no smoke and no loss of oil since I've I had her for two years now but there has always been a loose rocker valve sound that the previous owner said was checked and the mechanic couldn't find it. Maybe a bearing on the crankshaft? No idea but I do not get the gump I need to keep speed at 60 up a mountain highway.

ManzanoNissan wrote: ↑

Sun Aug 22, 2021 7:55 am

Solved. ...

There's a marginal increase in performance but when I drop to fourth on these mountain highway passes, I still loose acceleration with the foot to the floor. She's not exhibiting any symptoms of blow by, no smoke and no loss of oil since I've I had her for two years now but there has always been a loose rocker valve sound that the previous owner said was checked and the mechanic couldn't find it. Maybe a bearing on the crankshaft? No idea but I do not get the gump I need to keep speed at 60 up a mountain highway.

That's good news The rocker noise may be an easy fix if it's not from worn out parts. Your KA24E engine does not have hydraulic lifters, which is often the cause of such noise when they get sticky from varnish buildup, but those valve rockers do have hydraulic tappets, instead of old-school adjustable valve screw tappets. Hands down the best oil detergent I have ever used was CD2 Oil Detergent to clean up and quite that noise I would get in my old '91 Pathfinder. Sadly, CD2 is no longer readily available. Liqui Moly Hydraulic Lifter Additive may be a good choice for you to try out for cleaning up and quieting down that noise. This is not an instant fix, if it can work at all in your case. It takes at least 50 to 100 miles of driving for the product to work its magic. I steer away from fast acting and aggressive motor flush products on older engines as they can have detrimental effects to older engine seals.

Ah hadn't thought of an additive to clean the engine. Good call, will try that out thanks MD!

You're

Hey MD, I ordered the Liquid Moly and I also got a tip from a fella in an Autozone. I was telling him I have a dry metal plate clanking sound when I switch gears between 2 and 3rd. Told him I think I was low on trans fluid or the clutch plate is beginning to go and he thought it was the plate for sure. He also said that could be the reason for the sluggish performance up steep highway's, dropping to fourth and still losing speed with the foot to the floor.

He said his truck's clutch plate was going and the same thing was happening to him. Theory is the plate isn't fully disengaging, preventing full rpms.
I'll look into it on my end but thought I'd share for any one else.

ManzanoNissan wrote: ↑

Fri Sep 03, 2021 7:44 am

Theory is the plate isn't fully disengaging, preventing full rpms.

That's not how a manual clutch works. The pressure plate, pinching the clutch disc against the flywheel, is always engaged until you depress the clutch pedal. If the clutch pressure plate was worn out so that the pressure it exerts to pinch the clutch disc between the pressure plate and flywheel faces was too week to fully disengage when you shift gears, you would be grinding gears every time you shifted. The same thing would happen if your clutch throw-out bearing was not doing its job because the clutch cable was not adjusted properly to allow the bearing fork to push the throw-out bearing far enough to disengage the clutch when you depress the clutch pedal. Either way, if you are not grinding gears, that's not the problem. On the other hand, if the clutch disc friction plates are worn out and slipping when it should be fully engaged, then that would make you lose power. However, in that event, your RPMs would rise as the clutch disc slipped. The clanking noise you hear could be the shock absorbing clutch disc springs, and therefore the clutch disc, that are worn out and loose.

Understood. No not exhibiting any of those problems at all, just the curious 'clank' - sometimes when I'm sloppy on the foot/clutch movements. When I'm slow, and exacting there's no sound I've noticed. I'll add that to the list for inspection. Enjoying this old clunker and fixing her up along the way. Appreciate the help, thanks! Yet to receive Liquid Moly cleaner, due to arrive Friday.