TomX8

I've been googling around and found this specific thread about a man having trouble to restart his engine after it stalled.

Low Voltage to Coil Starting Issue | Shamrock Boat Owners' Club

It turned out that although the battery terminal, ignition and rest of the system were at full voltage (12+), the coil input voltage was between 6 and 7 volts, not nearly enough to fire a hot coil. Het put them to 12V and BANG, the engine fired up right away. I've read out my OBD2 data and quite often I have found that the engine starts when the voltage gets to atleast 11,5V. I've been reading out the catalytic converter temperature and it only starts to rise in 0,1 increments Celsius when it gets just before the point before it fires right up, and that's after 10 seconds of cranking. The engine is flooded aswell and it starts out smoking the driveway.

Now with new OBD2 data I found this trend again, and decided to measure the voltage from the coil connectors. The symptoms sort of fit the theory that the coils may fire, but it being too weak to actually ignite the mixture.

I will try this out and post the details of my findings.



Just before that the voltage was 11.2, and the engine cranked 480rpm. I will also calculate how the engine would start by rolling it down a hill and starting it in 6th gear at the speed when it should turn the engine around 400-450rpm while the battery remains at 12.8V. If the engine starts within 2 seconds of rolling and releasing the clutch, it may confirm that the voltage drop may have something to do with it.

I've also had cases as seen here, that once I stop cranking, the engine takes a second or 2 and launches the engine:

TeamRX8

iTrader: (25)

There's a huge difference between 6v and 11v on a 12v system

You don't seem to know that the RX8 pcm has voltage correction built into the ignition dwell table

Higher voltage doesn't just affect the coils, it cranks the engine faster too

Plus you're reading battery voltage and not the actual voltage at the coil then just making that assumption, which is in complete contrast to the situation in the basis article

You're like a crazy scientist without the scientist ...

TomX8

I also came here to check with you guys, as the information that you just gave is pretty important. I know I was reading battery voltage, my intention was to measure the coil input voltage with a multimeter.

dannobre

iTrader: (3)

Wouldn't hurt to check...but the difference is likely not going to be much unless there is a problem with corrosion or poor connections in a fuse or relay