COPs and slight misfire in park.

[mremington]

After a recent spark plug blowout I changed plugs and coils with all new motocraft brands and ngk 4177. Still had a slight "misfire in idle at park or neutral". I can hear the misfire and feel it from both exhaust pipes but its very slight. Swapped plugs again for motocraft sp433 iridium. Still the same thing. Is it possible I've got a bad brand new cop. Ordered the from summit racing and they looked brand new. Any way to test voltage to these. Ive seen some members recommend MSD blaster or other coils that perform a bit better. There is no problem with acceleration or WOT, not a hiccup, its just in park or neutral at idle. Cleaned MAF and IAC, new air filter, cleaned TB. Gonna do fuel filter next as I just ran a bottle of techron through the tank. Any ideas? Thx.

[fastblackmerc]

After a recent spark plug blowout I changed plugs and coils with all new motocraft brands and ngk 4177. Still had a slight "misfire in idle at park or neutral". I can hear the misfire and feel it from both exhaust pipes but its very slight. Swapped plugs again for motocraft sp433 iridium. Still the same thing. Is it possible I've got a bad brand new cop. Ordered the from summit racing and they looked brand new. Any way to test voltage to these. Ive seen some members recommend MSD blaster or other coils that perform a bit better. There is no problem with acceleration or WOT, not a hiccup, its just in park or neutral at idle. Cleaned MAF and IAC, new air filter, cleaned TB. Gonna do fuel filter next as I just ran a bottle of techron through the tank. Any ideas? Thx.

Take one of your old cops and start swapping it with one of the new ones. When the misfire clears up you've found the bad COP (if that's the problem).

Make sure the COP connection on top are good.

[GoldPanther]

a weak or bad coil makes the misfires more noticeable when the engine is at warm temp. Also when driving at high speed but at low rpm. Test drive at around 43-45 mph with the overdrive fully engaged, slowly give it a little gas and if it stalls then you have a weak coil.

[Ourobos]

Triple check all electrical harness connections at each coil

[mremington]

Ive done the part where i accelerate around 35-45 even uphill and there is no hesitation at all even with the engine load at 96.6 or so according to the gauge.
It's one of these pesky issues thats just bugging me. And the misfire isn't bad enough to kick or buck in park, just can feel it slightly in the seat. There are other times it smooths out completely in drive or even in park after a long drive and its warmed up. Very frustrating. thanks again.

[mremington]

I'll also try and clean the COP connections and make sure they are tight and not frayed or bent bad, they looked fine the other day. Would a bunch of dilectric grease on the boots and springs help?

[fastblackmerc]

I'll also try and clean the COP connections and make sure they are tight and not frayed or bent bad, they looked fine the other day. Would a bunch of dilectric grease on the boots and springs help?

You just need a small dab of dielectric grease.

[mremington]

I'll check em again tonight, thanks. Can you test the COPs with a voltmeter? Would it show which was bad or low output even if theyre brand new?

[Zack]

From a stop, go WOT to about 90mph. That gives the pcm enough time to detect a misfire and throw a code

[mremington]

Done that, no codes. Unfortunately when I bought the car from Martyo we think it had a tune from DR on it. Runs great with then tune however it NEVER throws a code. Even after I had a plug blow out up into the boot it still didnt throw a code. we're guessing DR turned off a bunch of ECU error logging or something. I'm getting a new tune from Martyo ASAP hoperfully next couple of weeks and he's going to leave on every ECU code he can. I cant even get Mode 06 data to show up, which would at least help me pinpoint the cylinder to look at.

[BLACKMARAUDER04]

I had the same problem after blowing out #8 plug.
Drove for a week with a MISFIRE.
Going uphill in overdrive was very noticeable.
Took it back to the dealer.
Got the car back and it was fixed. NO charge.
I assumed one of the COPS was not installed properly.

[mremington]

Since my mis is slight and only in idle is swapping coils a good way to determine the possible bad one? Is there a better way with measuring voltage?
At this point im just gonna pull the COPs again, clean all the connectors and reseat the using some dilectric grease and see how it goes. Without the ECU data or mode 06 its annoying to track it down. thanks again!

[GreekGod]

I was told Autozone can test our ignition coils???

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