Ignition Coil Resistance

[skraps]

Had codes for misfire on all four cylinders, and random misfire, so working my way through trying to figure this out. Plugs & wires both good, looked all throughout the service manual and couldn't find what the ignition coil resistance was supposed to be at.

Also have code for upstream o2 sensor, wondering if that may be causing issue with misfire?

[slayerized6]

How's your battery and alternator?

[skraps]

Battery is only four months old, haven't tested the alternator.

[06T200]

The DIS coil should have around 1ohm for the primary (between terminals 1 and 2) - and the secondary around 5200 ohm. Look for cracks in the case.



Public source: https://www.scribd.com/presentation/...ngine3-Control

[skraps]

Don't think the coil is bad; no visible damage; primary res is 1.0; secondary 5.23k.

Car starts fine, no problems. Idle in park is a steady 1k; soon as switching into drive drops to 750 and starts sputtering and does so throughout driving; usually worse in lower gears. Onto the fuel system as I have time.

[avguy]

Try running with the upstream O2 sensor disconnected to see if there's any improvement when it stays in open loop.

[skraps]

Haven't gotten around to doing anything much lately but here's what I've gotten thus far:

Plugs/Wires are new

Battery
-Voltage Test: 12.37V
-Load Test: ~14.4V

Ignition Coil
-Primary res: 1.0ohm
-Secondary: 5230ohm
-Voltage to Coil: 6.3V

Battery bought in April, all good there. I would assume that after doing the voltage and load test that the charging system is all fine. Drive belt replaced in last three months due to squealing when AC was turned on. Since the misfire issue however, the belt squeals when the car is put into reverse. Have yet to start going through fuel system as I haven't had time.

Question: What should the voltage to the coil be? Should it be equal to battery voltage or less as it's about half when I check.

[06T200]

Per the schematic you should have +12vdc to pin B at the coil.



Pin B is the middle one on the connector.




So if you only see 6 volts something is not right, as this is powered from the fuse box.

[skraps]

I figured that wasn't right.. Don't really know much about the electrical, just been going through steps in guides etc on trying to diagnose the issue.

Ignition fuses seem to be fine, however going to go get new ones right now and see if that solves the issue.

[06T200]

Could be something on the same circuit shorting? I know that all power from the fuse block (behind the battery) is all 12vdc. Or should be. You can see 5 volt on the '5v reference' circuits, but the coil needs 12V to charge the secondary windings. I saw mention of a fuse in the diagram (EF17) to the coil - but it is listed as "not used" in the master component list for the same fuse.