Injecter stuck-open no pulse from computer need help!

chrysler
300m

#1

2001 Chrysler 300m. I ran a new ground wire from the injector to the computer because it had a burnt spot on it. I took it to a dealer and put a used computer in it and they programed it but the number 1 cylinder injector is stuck open. I also put a new coil pack and injector in it. Ive tested the computer and it will not pulsate. The injector is spraying gas constantly. I hope someone can help me out i"m at a dead end here. thanks.


#2

The computer has drivers that grounds each injector at the proper time to inject fuel into the engine.

So, it would appear that the driver for the injector for #1 cylinder in the used computer is stuck closed. And the injector is constantly spraying fuel.

Tester


#3

so you think its the computer? the reason i replaced the computer the first time was because #1 injector would not spray at all. I found the short in the wiring and ran new and now I’m worried that somehow the new wire has something to do with it? or could it just be a coincidence the used computer i got had a problem with the number 1 injector also?


#4

The injectors always have voltage to them.

The drivers in the computer grounds each injector to fire them.

Unless the wire going from the injector to the computer is shorted to ground, the driver is the only other thing that grounds the injector.

Tester


#5

that is what i though that the injectors always had voltage to them so when i fixed all the wires that were brunt i tape all the hots together and the grounds individually. so was that okay to do?


#6

If the wires are “burnt” then tape may not be enough, as the wire inside the insulation may be damaged and open.

“tape all the hots together and the grounds individually” ? depends. The 'hots" if they are individual wires, may be “hot” at different times, and connecting them may be a mistake. If you are talking about the wires to the injectors only, then you may be OK. Or maybe not.


#7

Here’s a typical fuel injector circuit.

As you can see, the injectors have constant power.

It’s the computer that grounds each injector to fire it at the proper time.

So power to the injectors can come from a common power source.

But the grounds must be separate for each injector.

Tester


#8

i tape the hots from the injectors and the coil packs together and tape the grounds individually inside of the insulation. i used tape that was made for that kind of repair tho and i tape the insulation back together too. should i re-tape the hots individually?


#9

thanks tester for that link an your help.i guess i am buying another computer


#10

Measure the resistance from that injector’s pulse ground (the corresponding wire) to chassis ground, with the ignition off. If it measures low resistance, a few ohms, that means there may be a short between that wire and chassis ground, which will cause the injector to pulse all the time. If there’s no short, then disconnect that injector from the wiring harness, and see if it sprays all the time then. If it does the injector is mechanically stuck in the on position, not an electrical problem.

My guess is that wire is grounded for some reason, that injector’s pulsed ground wire, and that’s why it is spraying constantly. If so, the transistor (sometimes called a “driver”) on the ECM that turns on and off to ground and unground that wire under computer control in normal operation may be damaged.


#11

Well the only thing I’ll add is that are you sure you got the right wire? I can’t remember what problem I was trying to solve anymore but I ended up running a new ground wire. Problem was I got the wrong one and shorted out one of the injectors. There were three black wires and I picked the wrong one. I don’t think it cost more than $100 for a real mechanic to fix the problem.


#12

can i cut # 1 injector wires and splice into # 3 injector wire four a wile?


#13

No, #1 would fire out of sequence.


#14

some cars fire 3 at a time if it it is a 6 cylinder tho ???


#15

That is referred to as “batch fire” and was usually only used on vehicles much older than yours

Not a good idea . . . in my opinion . . . to alter the fuel injection wiring


#16

thanks everybody for your help. but i put # 1 and #3 injector wires together and it runs find.i hope it will last untill i get the money to buy a new computer an have it reprogram a gain lol


#17

I don’t understand. It seems like you had a wiring problem, and made a temporary fix. And now it’s running fine. Why would you get a new computer? that’s big bucks.


#18

i dont know how long the computer will run 2 injectors off of the same driver


#19

What you need to do is pull the oil dip stick and smell if gas is contaminating the oil. If it is, that can damage the engine.

Also, if raw gas is being sent down to the catalytic converter, you’ll be replacing that along with the computer.

Tester


#20

If you just tied the common wire together, then there is no added drain. If you are actually driving two injectors from one driver, I would think you would have other symptoms, such as a overly rich mixture.

But if the driver didn’t die in the first hour, it will probably last for a day or two at least.