James Paventi

iTrader: (34)

Hi All,

I've been troubleshooting my car's misfiring since I've owned it and would like to run my efforts by everyone to see what else I should have a look at.

What's been done so far to improve the issue
- item - results
- new plugs and wires about 9 months / 1000 miles ago - no difference
- new coil wiring harness about 3 months ago - reduced WOT misses
- replaced leading coil this week with a used one - stopped at idle, Tesla coil like snap
- added one tick (smallest increment the PFC will allow) to the "water temp correction" table - 60%+ of cold fast idle misses removed
- The car has a HKS Twinpower. Check the link in my sig for other mods. It's misfired like this since I've owned it and across each mod as it was installed.

Here's some pics of the coil that I replaced ... definitely a needed fix ...


I'm fairly sure that the snaps that I mentioned above we a problem with the coil that's pictured above. Perhaps it had an internal defect / ground path near the high voltage socket? I let the car idle for 15 minutes while I tooled around my garage and didn't hear a single Tesla coil like snap. These would usually come at the rate of about one every two minutes. The car did miss twice though.

I'll drive it to work next week log my runs through second gear at WOT. The misses here are fairly obvious as rich spots where previously the tune was perfect.

Well, what say all of you? Have I overlooked anything?

Thank you for your effort and suggestions!

James

wstrohm

Have you ever looked at the stored ECU fault codes?

nismosilvia270r

iTrader: (5)

Pfc

James Paventi

iTrader: (34)

I drove the car for about 6 months before the PFC was installed. The stock ECU never lit the check engine lite.

Banzai-Racing

iTrader: (11)

It is strange how often I see the leading coil in this condition. L1 in perfect shape, while L2 is completely corroded. I have not figured out what is actually causing it to happen.

James Paventi

iTrader: (34)

I wonder if there is something presenting a ground for the spark in that area. Has anyone ever cut their defective coil apart?

Speed of light

iTrader: (8)

I've seen that kind of discoloration (due to excessive heat) as a result of the plug wire not being fully seated (and arcing) in the coil tower. It did not seem to have any adverse affect on coil performance in my case.

wstrohm

There are quite a few faults that do not light the CEL (writing of a stock ECU, of course) but which can be read out per the link in my previous post. (Just FYI)

James Paventi

iTrader: (34)

good to know.

Maximum

iTrader: (5)

Have you tried bypassing the twinpower? I had similar symptoms. Disconnected the twinpower and went back to stock ignition and everything was fine. The red light was still on on the twinpower box but obviously it was shot.

James Paventi

iTrader: (34)

Well, I ran the car home from work today, SoCal heat, A/C on, boosted here and there, favored red lights (so that the car could heat soak a bit) and then headed home.

I pulled into the drive way and then, bam, a complete miss. I wasn't outside of the car and so couldn't tell if the Tesla coil sound was present but it was definitely a misfire.

Next up, I'm I' taking Maximum's suggestion and bypassing the Twinpower.

James Paventi

iTrader: (34)

Hey Gang,

So ... I pulled the Twin Fire and the misfires are gone. I've been driving the car all week, A/C on, traffic, parked and let it heat soak, etc.

I'm thinking of replacing my Twin Fire with these (link). It'll be a while but I'll update this thread with results when it happens.

Thanks for all of the help! Especially Maximum.

James

James Paventi

iTrader: (34)

Here's a quick update.

link

More after I've driven the car for a while.

James Paventi

iTrader: (34)

Well,

I'm beyond happy with the AEM coils. The car now has zero misfires. Even when idling fast and lean in the morning. This is did by the way with or without the Twin Power, stock ECU and PFC.

The car pulls so much stronger past 5000 RPM that I'm convinced that something other than the Twin Power or leading coil was to blame. The trailing coils are a possibility as are the wires. The plugs are the still in the car so they are not the issue.

I'll put the Twin Power, PnP harness and plug wires up for sale this weekend with a link to this thread and an offer of a refund if there's a problem.

... another post if the sale narrows down the problem.

James