How Cold Start Injector System Works - 22RE-liable...

[RAD4Runner]

Hi guys, I thought this may help some fellow members, especially this time of the year...

From 1986 schematic...
Positive side of CSI gets +12V fr starter relay or neutral safety switch ONLY during cranking. At the same time, STA also gets 12V while cranking (starter relay contact is closed).
When cold, CSI contact closes, connecting STJ to ground, and therefore, providing ground to negative side of CSI causing it to spray fuel. At this time, resistance ("R" below) from STJ to ground should be very low. Unfortunately, Toyota does not mention the value of this resistance. I will update as soon as I get the chance to actually measure that.

When coolant gets hot, contact opens and disconnects STJ and CSI from ground. When coils get hot after prolonged cranking, contact also opens.

On 1988 22R-E, and quite possibly on later engines, ECU also takes part in grounding STJ when it senses cold coolant. Note the additional wiring (in orange) between STJ of CSI timer and STJ of ECU below.

Owners of 1987's, when you get a chance, pls check is you have a wire connected to STJ pin of your ECU and let us know what color.

Test specs are here:

UNFORTUNATELY, THIS IS MISSING THE MOST CRITICAL SPEC: RESISTANCE BETWEEN STJ AND GROUND. This determines whether CSI gets ground or not. When cold STJ-GND should be low. When hot, STJ-GND should be high. I'll update this post the next time I get the chance to measure actual RESISTANCE BETWEEN STJ AND GROUND.

VERY critical but often overlooked is good electrical connection between metal body of CSI timer switch and engine block because this is how it gets grounded. Therefore, threads of CSI timer switch and mounting port should be cleaned to bare, shiny metal.
This is not good. I cleaned mine with vinegar and battery terminal steel-brush.

keywords: cooling system, fuel delivery, fuel injection

 

[kc15842]

How is the fast idle controlled?

 

[RAD4Runner]

How is the fast idle controlled?

Sorry, I haven't had to deal with it so no OJT to share yet.

 

[kc15842]

So now with a good understanding of the cold start injector and the CSI time switch the last piece of the system for me was the fast idle during warm up. The system has an air valve located below the TB. Its a bit of a chore to adjust but if working properly adjustments is as high as ~1500 RPM at cold start dropping down to normal rpm once warmed.

 

[mholme]

3VZ-E Info

Chasing my hard cold start issue-The early 3VZE uses the same process for checking the time switch. And the same switch it would appear.



I found that my switch tested fine. The cold start injector also tested working when fired manually, however would not run when the starter was engaged. My engine was transplanted from a '93 3VZE into my '88 by a previous owner. The sensor connections changed between these years and I had noticed butt connectors used on them to connect a generic connector.



Looking at the connection from the CSI, I saw there was a black wire and a green/red wire.



I traced the wires back to the butt connectors and where they attached to the CSI switch and thought they may have been connected reversed. Lucky for me, there were two '88 3VZE 4Runners in a local junkyard and I was able to grab a section of harness/connector from one(The first one fell apart in my hand and the pins separated at the plug..) and compared the wire locations to how mine was hooked up and sure enough, they were reversed. So I rewired into the correct pins. Green/Red to STJ and Black to STA. This is with the locating nub facing straight up at 12 o'clock as you look at it.



The truck fired up on the first try this morning with temperatures in the teens...and snow. This has been about a year long struggle that I really never investigated and just kind of dealt with. Thank you for this thread, RAD!

Interestingly enough, the time switch and ECT sensor are from the original engine. The ECT sensor was also butt connected in with a generic plug. So my theory has changed on the butt connectors: They either fell apart when they tried to disconnect them (like one did on me at the junkyard), or they forgot to disconnect them when they yanked the engine.

I also tested the ECT sensor while I was in there and it failed to show a change in resistance between simulate hot and cold. I'm going to go ahead and change that out because I have a hard hot start too. The sensor is relatively new looking but is generic. The prices on generic range anywhere from 3-70 dollars. They are still available new from Toyota, so I went ahead and spent the 60 dollars for OEM.

 

[RAD4Runner]

I rewired into the correct pins. Green/Red to STJ and Black to STA. This is with the locating nub facing straight up at 12 o'clock as you look at it.

Awesome! Glad to have helped THANK YOU for the update and sharing the info ^^^ that could help fellow members.

Happy New Year!

 

[GaryFromMO]

Should the cold start Injector always spray at engine cranking?

Like as it's warm short spray and then when cold longer spray?

Or just when it's below a certain temperature?


Had mine working but after driving when you shut off the engine it doesn't spray and cranks quite a little bit before startup.


This morning when it was cold out started right up as it seemed to work great.


Any input would be appreciated. Thanks

1986 Toyota 4runner SR5 5speed 22re

Sent from my SM-G950U using Tapatalk

 

[Hyde802]

Awesome info as always RAD!