Bad injector?

[jd2131]

I started logging on my 90 talon tsi awd and noticed that once the car warmed up the 02 sensor was around .2 volts, but the car smelled rich. Messing around with the pocket logger I used the function to disable the injectors one at a time. Disabeling injectors 1,2 or 4 caused the engine to stumble, but disabeling injector 3 had no affect on the performance. Pulling the spark plug wire on no. 3 didn't change the idle/affect the way the engine ran. I saw that no. 3 was getting power in the wire. I then unplugged the injector 3 from the wiring harness. Again the car ran the same. Right now I would guess I have a bad no. 3 injector, but would like a second opinion/anything else i should check. Is there any way to check if it is the injector vs. the wiring harness for the injector without just replacing parts. I thought about attaching a DMM to the harness plug for the injector and seing if i could get a reading when the ecu sent a pulse to the injector, but i don't think the dmm responds fast enough to read short (ms) pulses. thanks
-Jon

 

[psychlow]

Yeah, you'd probably want to try an analog/sweep MM.

Have you tried resistance-testing the plug wire for that cylinder? Are you sure it's not grounding out on the valve cover?

Just some thoughts.

 

[jd2131]

I haven't resistence checked the wires, i did pull the wire with the engine running and held it near the valve cover, and the spark jumped from the end of the wire to the valve cover.
-Jon