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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?
How's your battery and alternator?
Battery is only four months old, haven't tested the alternator.
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.
Attachment 10492
Public source: https://www.scribd.com/presentation/...ngine3-Control
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.
Try running with the upstream O2 sensor disconnected to see if there's any improvement when it stays in open loop.
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.
Per the schematic you should have +12vdc to pin B at the coil.
Attachment 10511
Pin B is the middle one on the connector.
Attachment 10512
So if you only see 6 volts something is not right, as this is powered from the fuse box.
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.
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.
Before going to O'Reilly I pulled the two 30amp fuses for ignition 1 and ignition 2, they looked fine other than some minor corrosion where the fuse connects to the block. Replaced the originals, drove to O'Reilly without any obvious misfire, replaced both ignition fuses with new ones, drove back with no misfire. Even turned AC on for the ride back to see if it would cause any change and no issues.
Checking the voltage again going to ignition coil read at 6.5V
Thinking I'll take a longer drive later on after it cools down a bit to see if anything arises.
Happened to speak too soon. I had one short drive with no misfires, but when going out for a second drive had issues immediately. Just my luck that it couldn't be anything simple, so I guess it's time to delve into the wiring and hopefully learn a thing or two.
Would it be possible for a bad drive belt tensioner to cause misfire?
Not likely, nothing I have ever seen. They make noise that's about it.
How did the 6-volt ignition issue pan out? I would sort out the wiring issues before throwing any more parts at it.
Wasn't planning on spending money on the tensioner, just curious if anyone had heard of it being able to cause misfire.
As for the wiring, I soldered in a new ignition coil connector due to the old one having bare copper in a couple places. From visual inspection of the rest of the wire/wires in cluster didn't notice any obvious issues. Wouldn't know how to go about diagnosing any wiring issues other than from just visual inspection as I've only ever taken a basic electrical class and that was a few years ago.
I did have a wiring issue back in December & the shop claimed that the mail wire cluster going into the fuse block was melted into the base of the fuse block. They quoted more than I could afford to replace the two parts at the time so instead they ran a line from the positive battery cable into the wire cluster through a 100amp fuse. This negated the need for having the 50amp battery fuse in the fuse block, but while I was looking through the wiring I couldn't find anything resembling what they were talking about.
Unfortunately I'm unable to sell the vehicle due to a lien on the title so at this point, I think I'm just going to use the vehicle for local short distance errands until it dies.