Cold Start injector intermittent, HELP!
 

1986 Toyota pickup 22RE 183,000 2.4l Manual 4x4
I've been chasing down this issue where I have gotten stranded 4 times now.:rant: let me explain. Truck starts and runs (usually fires up instantly) I'll run errands or go to work then go to get in and wont fire up just turns over but not fire. I Checked spark and it has a strong spark. I ordered a LCE fuel pressure gauge and the fuel pressure sits at 31 psi, pull the vacuum on the FPR-Fuel Pressure Regulator and psi jumps up 5 psi so that checks out. I pulled the two sensors under the intake Left-white cold start injector time switch / Right-Green Coolant temp sensor. I checked the omhs and they both checked in specs, also cleaned them up. But this morning when I pulled the Cold start injector it fired right up then the CSI cut out completely(engine temp still cold)??? this is where I am confused, could it be a wiring issue. I read somewhere that it could be the Ignition control module that sits on top of the coil? I will try and upload a video I made this morning.

you need to describe more clearly what happened. reread your sentence that begins, "but this morning..."

Basically what i was trying to say was that my CSI will work great on first 2-3 cranks. then cuts out. as shown in the video.

i don't watch vids, but i read descriptions..

i believe the csi time switch warms up as it operates, eventually hitting a temp above which it won't allow the csi to fire. depending upon ambient temperature, this might only allow two cycles where it "works", and after that you might need to wait a bit before the csi will fire again.


however, i'm guessing rad4r (ray) will shed some light on it. i could be way off on the internal workings of the switch.

I'm about to the point of wiring a bypass switch to the CSI until I can figure out the real issue. Its my daily and need it to be reliable.

Yes, the issue is: the CSI will work then stop, warm or cold has no effect on the issue I'm having. Although after not starting and just turns over I let it sit for 30-45 minutes and try agin it fires up.

Good job putting us in front of that engine compartment, and getting the fuel pressure gage. Now you need not spend time doubting fuel pressure and can focus on the real root cause.


THIS.^^^

This^^^ lets the coil inside the CSI timer switch cool down and allows contact to close again.

Looks like your CSI works perfectly fine. How it works: https://www.yotatech.com/forums/f116.../#post52385373

You notice that when the CSI sprays you get combustion but when CSI does not spray you do not get combustion? That means it may not be getting fuel from the injectors.
Would you guys agree that the cause is most likely the brittle crimp(s) on the wires connecting negative side of injectors to ECU pins #10 and #20? (in red below)

Rick,
I suggest you inspect that harness. Please take pics of what it looks like. (Mine went bad when shop re-installed rebuilt engine and the techs did it themselves so I was not able to take pictures.)
While you're there, pls see IF 4WD and Reverse switch wiring are there and IF possible to get them out of there and route them else where? They don't need to be there and re routing them elsewhere may make future work on that harness easier. (Maybe rout them from starter to run along the right-hand inner fender?

https://lh3.googleusercontent.com/sx...=w1274-h753-no

That link is amazing! your a wiz I tell ya! I will clean out the threads on the cold start injector switch to eliminate any bad ground. I am a bit confused though how do I go about (probing) or checking the wires with it not running, lets see if I understand: so I leave the harness connected in the ECU and stab a test light in there or a voltmeter and it should be lit up without the engine running?

Aslo i've read that corrosion in the crimps of the wiring harness to the injectors is a common issue where the split is. Is there anyone out there out there who has gone through this issue of the split being faulty and having to completely rewire the injectors? How does the cold start injector related to the 4 main injectors?

Cool :)

I'm most certain it's the crimps. not the connectors. Check Terry87's thread. I think he did replace connectors, but I don't think you'd need to.
He also discusses using the "Noid" light to see if the injectors are getting pulsed.

You could do it the "scientific" way:
Disconnect ECU connector (pin-outs on schematic below-Note that Schematic is from 1988 - 1986 will not have the STJ pin connected).
With IG on but not running, Measure voltage at the ECU #10 & #20 (W and W-R wires. You should see 12V because when IG is on but not running, 12V "bleeds" through the injector resistors, through the injectors then to the #10 and #20 end of the W & W-R wires.
However, those injector pins are connected in parallel, so you still would not know which injector(s) is (are) losing connection and where the connection is lost. You would need to individually disconnect/connect injectors then probe #10 first, while someone wiggles the harness. Then repeat while probing #20.

If you're gonna do that, you would already be right there; Might as well see if you could unwrap that harness and check those crimps. IT WOULD HELP if someone who's done it could chime in and point where on the harness to open up to expose those crimps.

This diagram shows #10 and #20 on ECU connector.
https://cimg0.ibsrv.net/gimg/www.yot...54a288cf0f.png

Ok I will rip into the harness today after work. does anybody know what gauge the wire is? i'll stop by lows to pick up some more and some shrink wrap(running low). I did have to do the jump one injector to the next but this still doesn't explain how the CSI is connected to the other injectors 1-4. Also what does STJ stand for?

the csi is not connected to the other injectors in any meaningful way. it doesn't fire pulses, it fires a steady stream, but only when the key is in the start position, under specific temperature parameters.

Think I found the problem....

Don't know if the letters really stand for anything, but it's the pin that gets ground in order for CSI to fire.

Sweet!
So were those bad crimps? Did you have to remove the intake manifold to access that part of the harness?
If you need extension wires, best to get automotive wire. They have thinner but more numerous strands to be flexible to withstand vibration.

Ok so all yesterday I was working this crimp problem. I will post a video here shortly. The CSI and the Cold start timing switch are both connected by a dark green wire for one pin (probably how they talk to one another) then the other pin on both the CSI and the Cold start timing switch has a black wire that is crimped into the harness on the same thick black wire that is coming from above the ECU. I don't know if this is a ground wire or not??? everything ive seen shows that the ground comes from the cold start timing switch body on the intake manifold. The reason I'm mentioning this is because the wire internally has this weird black goo on it and wont let me soder(im questioning it and thinking about running a new wire but don't want to remove the entire dash to find it. my quess is its either a ground or tells the CSI and the cold start switch when its trying to start?

Rick, Sorry, hard to analyze a verbal schematic. Pls
1) See my schematic, annotate where u think those wired are and share, OR
2) Post a picture, annotate with arrows pointing to what ur taking about. Remember monitors and cameras may not always show colors accurately.

1986 should absolutely NOT have CSI or CSI timer switch wire going to ECU. 1988 does. But who knows how much sake the factory worker has had the might before. LOL!

https://cimg6.ibsrv.net/gimg/www.yot...274d53c69.jpeg
https://cimg7.ibsrv.net/gimg/www.yot...23374a202.jpeg
https://cimg8.ibsrv.net/gimg/www.yot...32243ab9f.jpeg
https://cimg9.ibsrv.net/gimg/www.yot...60dea5936.jpeg
https://cimg0.ibsrv.net/gimg/www.yot...a4f7c1426.jpeg

Good video. Tnx, Rick! I'm on my phone so can't findy schmatic easily.
what are the blue and black wires?