davethomson

2001 Acura el (Honda 1.7L VTEC)
- miss-fire cylinder 3 code. New coil pack and plugs, good compression but won't fire.
I changed injector #3, still dead cylinder. I tested the injector wire with a noid. The Noid glows but doesn't pulse.
Now what?

schreps

What did the sparkplug color look like?

"but won't fire" - do you mean 1) no spark? OR 2) have spark but cylinder is not running?

if the former, 1), does disconnecting the coil pack indicate not firing? if not firing swap the pack with a running cylinder to make sure the pack is good. If the pack is known good then the signal from the ECU is probably suspect. Check connector pins and probe wires back to ECU for open or shorts.

if the latter, 2) then,

Pull the injector connector, with the engine running or key on check using a DVM that you have solid battery voltage on one of the connector pins.
If good connect a test light to battery positive, and probe the connector pin (ECU pin) that did not have battery voltage while the engine is running. Is the test light flashing?
If it is then the ECU and battery circuits are probably ok.
Next would be to look at the voltage waveform on the ECU pin (with respect to ground) to see if the injector turn-off voltage spike and pintle movement waveforms are normal, but you need an oscilloscope for this. A Power Probe may also work but it doesn't show the waveform only indicates the spike amplitude...
If you have a scan tool look at the long term fuel trim for a lean or rich condition. If the ECU is adjusting lean the injector is probably leaking. If rich then it may be plugged or not functioning correctly.
If none of that then do leak down test.