Number 4 injector not firing

[TD05tsi]

Hey,

I just resently rebuilt my motor and uppon putting it back in i found that my #4 injector will not fire. so what i did was swap the number 3 and 4 injectors and the problem remained on the number 4 so i can rule out bad injector. ok so then what i did was check resistance between the injector plug and the ecu no problems there, then i figured that my emanage might be malfunctioning so i took the number four and wired it back with just the ecu still no fuel on the number 4. while looking at the wiring diagram i can see that the injector is connected to what i guess is called the ignition suppresion resistor if anyone can tell me if they have had a problem with this or where it is located so i can check it that would be great thanks alot


Kevin

 

[luv2rallye]

Your #4 injector ballast resistor is shot - replace it (or them). They are in a metal box on the engine side firewall in the middle. Should be 5.5-6.5 ohms each.

 

[TD05tsi]

ok thanks alot ill give that a try


Kevin

 

[steve]

The turbo cars have ballast/curent limiting resistors in series with the injectors. You should see close to battery voltage at the injector on one pin to feed power to the injector. The ECU grounds the other side of the injector when it wasnt to fire it to cause current to file throught the injector.

Steve

 

[TD05tsi]

ok i tried all that all the wires checked good so i desided to check resistance between the positive and negative of the injector plug and i got a current so it is shorting out so i unplugged my ecu and the short went away so im figuring there is a short in my ecu im gonna try and fing another ecu to try any suggestions


Kevin

 

[steve]

i desided to check resistance between the positive and negative of the injector plug and i got a current so it is shorting out

The injector has resistance. on a turbo car it's a low resistance. It's from the winding of the coil in the injector. Since I can't really figure out what you were measuring I can't say much more.

Steve

 

[TD05tsi]

im just measuring current thru the plug possitive and negative it shows a short while the ecu is connected but when you disconect the ecu the short goes away as if it is shorting thru the ecu this is with the injector disconnected ill send a pic later plus i guess from what i have read 1 injector not firing is a symptom of ecu failure


Kevin

 

[Travi2506]

May sound dumb, but do you happen to have a coil-on-plug kit? A buddy of mine had the same problem. He checked everything with the injectors and wiring. It ended up being a bad coil on his kit.

 

[TD05tsi]

not sure i understand what you mean by coil-on-plug kit

 

[Travi2506]

not sure i understand what you mean by coil-on-plug kit

There's no plug wires... The coil is right on top of the spark plug. Buschur and Dejon Tool both sell them. If you don't have that check your coil pack...

 

[TD05tsi]

oh ok i see what your saying i didnt even know they made a indivisual coil kit but i already checked my coils they are all firing thanks though

Kevin