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Supercharged AP1, stock engine, AEM Series 2. Some might recall my posts in other coil pack threads but this issue deserves its own thread.
Brand new genuine AP2/K20 coil in cylinder 4 "failed" at 7000rpm WOT in 1st gear. Limped home and started testing. Checked coil pack connector, it's totally fine and not broken in any way. Wires don't look frayed either. Started swapping coils around and the AP2 coil from cylinder 4 worked perfectly fine in cylinder 1! Cylinder 1's coil pack that is working DID NOT WORK in cylinder 4! None of the other Amazon Denso or my new AP2 coils work in cylinder 4 EXCEPT THE ORIGINAL AP1 coil...?! I haven't tried a 9k pull with the AP1 coil in cylinder 4 yet but, why is this happening??
Spark plugs were new. NGK BKR8EIX. There plug gap was incredible... I couldn't believe how stretched they were. So I went back to my previous set of the same coils that have proper good gaps.
Maybe this a fake NGK...? Less than 500 miles on this set
A new set of OEM-spec plugs will probably cure this. But you can try just setting this one to the proper gap. Notes here from as long as 11 years ago indicate the BKR8EIX plugs are questionable and at a minimum need t be need to be gapped -- this one ain't correct -- while the proper OEM PFR7G-11S come ready to install (do NOT re-gap or put anti-seize on the threads). Since the OEM NGK plugs are readily available I've seen no reason to experiment with other plugs or try to save a small amount of money.
A new set of OEM-spec plugs will probably cure this. But you can try just setting this one to the proper gap. Notes here from as long as 11 years ago indicate the BKR8EIX plugs are questionable and at a minimum need t be need to be gapped -- this one ain't correct -- while the proper OEM PFR7G-11S come ready to install (do NOT re-gap or put anti-seize on the threads). Since the OEM NGK plugs are readily available I've seen no reason to experiment with other plugs or try to save a small amount of money.
-- Chuck
Thanks for the reply. Note that BKR8EIX are recommended and widely used for boosted applications such as mine. My first set have stayed well within their tight gapped spec but this set is clearly fake. I'd rather not even try to gap them back to spec. I'm running my previous set of the same plugs now. I have stock PFR7's but won't need to run them.
Did more testing today but with my multimeter. What a revelatory experience...
Coil connector 4 is out of spec with the others. Voltage is good but resistance and continuity are way off the other connectors. Resistance was pretty low on coil connector 4 whereas on the others it was high and they matched each other nicely in the 16.60 ish range. Coil connector 4 was less than 1 basically. Continuity indicator lit up bright red on the multimeter for connector 4 but was very dim on the other connectors.
Coil packs all tested around 11.50 ohms which is in spec except the AP1 coil in cylinder 4 - it tested at 12.50 or more. That's out of spec according to a video I saw of another AP1 test and this might explain why it works "better" with the out of spec coil connector 4...?
So... What do I look for now? High or low resistance in wires means what? What should resistance and continuity values for healthy S2000 coil pack connectors be?
Daym that looks like a huge gap. Definitely looks like the gap is too large to make a good spark. Out the box my plugs came .030 of the same plugs. I was experiencing spark blow out at that gap and dropped them down to .021 and my problem went away.
Daym that looks like a huge gap. Definitely looks like the gap is too large to make a good spark. Out the box my plugs came .030 of the same plugs. I was experiencing spark blow out at that gap and dropped them down to .021 and my problem went away.
Glad you found out! The other problem I have though is my coil pack connector for cylinder 4 doesn't work with any new coils. It's got a way different resistance and continuity reading than the other 3. Any advice on wiring or something that could cause this?
Make sure it definitely not a plug gap issue. Any chance you replace the coil connectors because they become brittle and perhaps may have reconnected the wires in wrong slots?
Ok looking at the Electrical diagram. All coils are powered by Fuse # 4 under dash box. Pin 3 Black/yellow wire. Pin #2, black is your ground and is grounded at G101, located in rear of engine against Firewall. Pin #1, white/blue is controlled by the pcm. Check your wires and make sure you don’t have a break in the wires somewhere or take a laptop and see if you have any activity in the AEM tuner.
Make sure it definitely not a plug gap issue. Any chance you replace the coil connectors because they become brittle and perhaps may have reconnected the wires in wrong slots?
I've never reconnected them. Still original and none of the clips are broken. Might need to open up connector 4 just to see if any wires are somehow touching and shorting out
Ok looking at the Electrical diagram. All coils are powered by Fuse # 4 under dash box. Pin 3 Black/yellow wire. Pin #2, black is your ground and is grounded at G101, located in rear of engine against Firewall. Pin #1, white/blue is controlled by the pcm. Check your wires and make sure you don’t have a break in the wires somewhere or take a laptop and see if you have any activity in the AEM tuner.
Thanks for this! I'm thinking it could be a bad fuse so I'll swap it out with another good one including the under hood number 46 fuse just in case. I'll try to get my hand around to the G101 wire and see if it's loose in any way.
Will also connect my laptop and see what the AEM Tuner shows up
07-05-2022, 09:33 PM
Bizarre Coil Pack Problem - help!
