Oct 20, 2021

Misfire : RB26dett Ignition Coils

By Sean Morris October 20, 2021 coils, Featured, ignition

This ignition coil has a crack where marked. See pictures below for more details

We had a couple of issues come up with the Saurus car. While at Cars and Coffee one weekend, it decided to start to run funny. It wouldn't go into boost without cutting out. I drove it back home and started some diagnostics . It appeared that fuel pressure wasn't rising with boost. I figured that a line in the tank might be leaking. However it turned out that it actually had two fuel pumps in the tank, and one had failed.

Ernie replaced one dead pump with another stock pump we had. Installed an Apex Electronic Fuel Pressure Gage. Fuel pressure was good, but the car was still cutting out. Onto the next step of troubleshooting, the ignition system. Removing the center plate and harness, it was a little crispy, and a couple of the connectors had pieces come off them. New Wiring Specialties harness, and that issue was cured. The next thing was cleanup, and sparkplug change. Since this is a special car, I broke out a set of my "best" plugs for an RB26. For this car I had a full set of 7436-9's and they went in.

NGK R7436-8

NGK R7436-9

NGK R7436-10

We pulled the boots of the coils, and Ernie noticed one of the coils had a more pronounced crack at the parting line. We noticed, it but we didn't actually do anything about it. Just noted.

Around the crack, you can see marks/scratches where it appears the spark was leaking

New plugs, new harness, cleaned all the coils up, put dielectric grease, and took the HKS twin power out of the loop (for testing). Went out for a drive, and while it was much better, it was still misfiring at about 12 psi of boost. Back to the shop, pull the cover back off. Hit that one coil. Replaced, out for a drive, and its cured. Car is running as it should again.

When you see something wrong, it probably is something wrong. Observation in troubleshooting is big. Sometimes you just need to take a minute with some light, and look at things. Make sure you see or don't see something.