Steguis Motorsports: Flooded Cylinder 1

Sunday, August 11, 2024

Flooded Cylinder 1

I was getting ready for my next track day when the car wouldn't crank. At first I thought it was just a bad battery so I swapped in my spare battery and same thing. It would try to turn but stop like it was stuck. I was looking everywhere for anything broken and realized I was smelling fuel but saw no fuel leak so I started pulling the plugs out and found this. The spark plug in cylinder 1 was very dark and went from fuel and I could smell a strong scent of fuel coming out of the cylinder. I checked the other 3 cylinders and they looked just fine.

I then took a wrench to manually turn the crank and fuel started com up through the spark plug tube. For some reason the cylinder was flooded with fuel. I soaked up all the fuel as it came up as I kept manually cranking. Once I felt it had cleared and let it dry overnight, I changed the oil and put in a fresh set of spark plugs and tried to crank it and it started for a few seconds then died again. Took the spark plug out and it was wet with fuel yet again. I cleared it out again and just double checked the compression to make sure it was still and and it was still above 240.

So shutting off my fuel pump and cranking allowed the engine to crank but as soon as I applied fuel it would flood. Either I wasn't getting spark or I had a leaky injector. I tested for spark and sure enough I had spark so it wasn't that. Before checking the injector, SJF said to get a noid light and see if I was even getting proper pulses to it. This is when the literal lightbulb turned on. The noid light should be off normally and pulse as the ECU signals the injector to fire. Instead, even with the key just in the on position it was already on causing the injector to just stay open.

Noid light staying on

I then wiggled the wires and the light would flicker on and off. Aha, I had a short somewhere. I stripped back all the harness wrap and the heat shrink wrap around the solder joints. The joints looked good but I'm guessing at some point it poked through the insulation somewhere causing a short so the plan was to apply new insulation. I also thought it'd be a good opportunity to replace the very brittle injector clips that were falling apart with each touch. Perhaps the short was there as well.

New injector clips

I depinned the clips and slid on some new high quality heat shrink tubing that has adhesive on the inside to prevent it from sliding around. I then put the pins in the new connectors. I wrapped everything in high temp harness wrap, the kind you see on most Euro cars, and then re-tested then noid light. This time it stayed off as expected and no amount of wiggling caused it to flicker. I changed the oil yet again and put in another set of fresh injectors (the previous one I tried was a cheaper variation I could easily get my hands on as a stop gap). It fired up, idled just fine and had perfect air/fuel ratio. It did take a while for the exhaust to stop smoking. All that oil and fuel and had to get burned out but once all that was done she was back to driving like a champ.