Topic: 2.5, Cyl #1 injector not opening, low voltage, Bad Computer??

[Bigboi]

So i was driving back to my shop from a delivery and as i turned onto my street i hear this hissing noise, look around, notice my temp is rising!!!...... i shut it off and coast to my shop, opened the hood and discovered the heater core hose blew.......... Next morning, remove the heater core hose, replace lost coolant, do an oil change while im at it, Crank up my Beater, and its running like crap, So i did a spark check, #1 is getting spark, So i proceeded to a Compression test... 145-150psi across the board, pulled the injector wires, to find #1 injector wires completely peeled and stuck together, i bought another pigtail, put it in place, and #1 injector will not open, i then pulled out my multimeter, and found continuity between both ends of the white/blue tracer and the green with orange tracer, so the wires are able to send signal (Theoretically)

 I then switch to 20v DC to check if theres any voltge to #1, and i read 0.3 to 0.9, barely hitting 1.0, i then switch to #2 cylinder plug and compare voltage, 2.3 to 3.5v Across #2 #3 and #4

So i Believe ive narrowed it down to a bad computer?? (i question because im not sure, but with what i checked, seems to be the only logical explanation

EDIT: Im reading that the crank sensor could have something to do with it, but im gonna look a bit more

[VA_YJ]

A few things to consider:

Problem could be in the harness, especially if it got hot.
The computer plugs into the 60 pin connector on the harness, pins can get corroded, make sure connector is tight and pins clean. Pin diagram will identify #1 injector pin.
The most common problem with computers is bad capacitors, but that is not your problem - it affects starting (delay in caps charging up).
I keep a spare computer to aid in troubleshooting - if you get one, it need to be the model for the correct year and transmission

[VA_YJ]

pin 16   White w blue stripe   Injector #1   Pulse signal

[VA_YJ]

Throwing any DTCs (trouble codes)?

[Bigboi]

i was indeed able to locate another computer, i was hesitant on purchasing it because of the JYs policy, i couldnt research the difference in the final letter D or E being  different computers, After finally getting back to a charger, i checked online, and it indeed said it was for my vehicle, so i put it in, plugged up the injector with the pigtail, turned the key, and almost got shot in the face with gas  , i havent been able to fire it up because the rain came and has haulted my progress in finishing it up...... I had to change out the Intake/Exhaust gasket and replace the studs that fell out


No i havent had Any CEL for a while come to think of it

[Jeffy]

You should get a Code 27 if the injector isn't working.  It might not always throw a CEL.

[Bigboi]

Im gonna pull my cluster, i think the light for the CEL is dead, But, i was able to get the engine back together, new gasket, new injector rings, and another computer, and my Dakota is back up and going

Reading my compression numbers, im wondering if my rings didnt set in properly, because i only read a max of 150-155psi per cylinder and all at the same range of 145-155psi, but ive gotten over 65k out of my rebuild so far


Coincidentally this month i got into Soldering, so im gonna pull the computer apart and see if i can find any issues with it

[VA_YJ]

The computers are "potted" - covered with rubbery coating.  You can't always see what's underneath without removing the coatings.  I've done a lot of work on PC boards - you need to be real careful not to overheat components.

Have you checked to make sure the white/blue wire is not grounding onto the other (green/orange) wire?  If the insulation got hot, there could be an unwanted connection.