OOPS, Sorry. Yes, it's from Rasalibre's 86. So many Hard Start/Rough Idle threads, it gets confusing - LOL!
I updated above post with one from 1988 (electrically same on THA-THW-ECU part of the circuit).

Here's for the 1988 22RE again.
O.P. check out the THA and THW circuits:


Possibly the wire or another bad connection there. Also, did you check the crimps between ECU and fuel injectors like YotaRick did?
One thing, I'd like to do to mine is monitor THA voltage when it happens and when it does not happen.
I'm considering investing in a couple of panel-mount voltmeters like this for diagnostic purposes... (https://www.alliedelec.com/m/d/efce8...47d02630f4.pdf). Can be connected to whichever part of the circuit I'm testing and monitored in real-time...

 

You might need the 3M-brand mounting package
https://www.yotatech.com/forums/f116...icator-303218/

 

That's nice, Scope. Thanks!

 

Ok im having the same issue. Is the coolant temp sensor the one that sits on top of the intake where the upper radiator hose connects? I just have a prong sticking out with no wire plugged into it. Is the little wire with a blue plastic clip supposed to connect to it?, What color is the wire i might have to re-dig into my harness

 

That sounds about right, pictures would help also remind everyone the model year we don't get signatures (if you have it there) on the mobile layout.

Typically wiring on these only logically reach to where they need to be (length and bend memory).

When in doubt you can probe the wire, resistance or continuity setting on a multimeter, from the engine bay to the ECU (preferably unplugged since some are shared internally).

Inside the cab is also a good place to verify wire color, it won't fade as bad there.

 

Every picture tells a story.
A picture paints a thousand words.

 

I could be wrong, but I think the one you're describing runs the dash, and the one under the throttle body feeds the ECM... And blue sounds right. I just unplugged mine tonight, but I was following your steps and tearing the harness apart. I saw a lot of wires...

 

So, seems like I've got a popular topic going here. I'm pretty proud of that. I'm all about finding solutions together.

I've been slow to work on mine. I took the injectors out and did the resistance check last week, as mentioned. Had already bought new rebuilt injectors. Said screw it, already have them, so I put them in tonight. And I *really* wanted to just try to get the plenum back on, but I'd be kicking myself if I did and it didn't work, and I didn't check these crimps.
So...




So really, only the yellow crimp was corroded, and honestly... not that bad. I hit it with some electronics cleaner and a brass wire brush, and it shined right up. And yes, I looked close. It was mostly corrosion of the crimp itself. The wires really didn't have much down between them. And I gave it a dab of dielectric grease before wrapping them back up.

Next time I have time, I guess it all gets buttoned up and say a prayer to Fudō Myō-ō that this works.

 

Attached is a photo (thanks lce), the two temp sensors are the vertical ones. Middle of the intake, and forward sections. They share the same threads, and the wires will reach either location. Pretty much clear as mud.. In the OEM configuration the forward one is the sensor for the ECU, the middle one runs the dash gauge.

(Edit with strikethrough, I probably should not post after midnight *grin*)

You can continuity probe at the ECU to the engine bay to be sure which is which with the ECU connected with out interference between the two.


Lce intake image

 

Very good images that show the fuel injection interlink. (Can you redo the middle photo with better focus, something like your hand behind the wires so it gets the focus depth better).

These deserve a sticky or write up of the injector splices. Best I have seen by far.

 

according to what I've found neither of these sensor feeds the dash guage. ​​​​​​​One is the cold start injector thermal switch and the other goes to the ECU. I found a youtube vid but having trouble w link. Gotta get to work and will try the link again. Guys site is 22reperformance.Com but I can't find the link darn it. Working on it..........

 

One of the temp sensors is not vertical, it is horizontal, just to the right of the CSI timing switch. This is the one I've had to replace twice, and I'm pretty sure it's the one that feeds the ECU. It has an actual connector (green?), whereas the one in the middle is like a one wire pronged deal (blue?), and I think that runs the dash.


The other upright thing is... well, I don't know, but it looks like this:

 

So this is the coolant sensor im talking about and this is the little blue clip that is not connected to anything. PO replaced the sensor that sits in between injector 2-3 with a universal one that reads on a separate gauge in the cab due to my dash having a electrical short and fried. I just replaced the one that sits horizontally next to the cold start injector time switch but why does the 22RE have so many? What does this blue wire connect to? and lastly would this be a reason to also have a hot start issue.?

 

 

Sorry I was wrong on which two sensors were being described. Disregard last post.

 

*EDIT*
Looks like it's maybe just a year difference whether the thermostat housing had that or not. So... don't know. Sorry for useless post.

 

Correct, there is also a second style of thermostat housing for AC equipped 22re. It has two ports, one for 4wd and one for AC. They have different shapped terminals.

 

That one is the bimetallic vacuum switch, for egr.

 

Ah. Makes sense.