I'm at a lemons race in road Atlanta and hoping my race prep bros can bail us out. We have an non turbo NC (sorry bros) with a 2.5 swap. It went from a top end mis to completely losing cylinders 1 and 3. We have checked and originally found issues with the grounds but even after fixing, no luck. We know 1 and 3 are dead because if we pull coil plugs on 2 and 4 the engine stumbled but not 1 and 3. We tested voltage on the power line as well. The plugs on 1 and 3 are black and the car back fires on throttle lift.



Sorry for the wall of text I'm on my phone at the track. Looking for any words of wisdom. Compression test was also done.

 

Hmm have you tried actually swapping coils? Could try that just to rule out some dead ones. Black plugs is interesting for a miss, usually indicative of running rich. Maybe fuel injectors sticking open and causing plugs to foul?

 

What's compression test say?

 

We did swap to completely new coils. We even pulled the rail to swap injectors around but the issue persists on cylinders 1 and 3. I'm not surprised about that spark plugs on those 2 being black as they are getting no spark and only fuel. We did also swap spark plugs.

I wasn't there when they did the compression test. I just got back from AutoZone and they said it was good.

Thanks guys

 

Looks like we found the problem. Even though you could test good connections through the could plug with a multimeter, when you plugged them in, they didn't make good connection. Swapping to a new set of electrical plugs for the coils and she worked immediately

 

 

Wait so we're not going to get a full engine build now? Awww

 

NC coil connectors and the OEM coil wiring are junk. I had so many issues that I finally added DTM connectors so that I could keep new spares ready to go and quickly swap them out at the track. I also used a much heavier wire size than what's electrically needed to add some mechanical strength against vibrations. Can't remember if it was 12, 14, or 16 gage but I never had another failure after switching to the heavier wire.

I also recommend buying new pins and connectors from Ballenger instead of buying the 4 pack pigtail repair kits from amazon or ebay or whatever.

 

At that point I’d just pot the bare terminals onto the pins at the coil, sans connector, and have a Deutsch connector on a pigtail, professional motorsport style. Did not know that the duratec coil harnesses sucked though, good to know.