Forum » General Tuning Discussion » Link g4+, RB30, LS1 coils, spark at key on engine off, pre crank

Link g4+, RB30, LS1 coils, spark at key on engine off, pre crank

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hi Guys,

i have just fitted a link fury to my rb30 set up as sequential fire with cam and crank sensors.

I am working on tuning the cold start - E85 and every time I turn the ignition on after attempting to crank it prior to poor cold start, it sparks once and back fires through the exhaust. This is at key on engine off prior to cranking. Obviously it has unburnt fuel in the exhaust but why is it sparking at key on?

my guess is it is relating to my trigger set up. I am running a 36-1 on the crank with a Hall effect motec sensor and your typical single pick up off the cam as a home sync also using the motec sensor.

I am planning on switch to a 12 tooth trigger wheel on the crank as this set up has caused me issues in the past with a reluctor sensor and my previous ecu.

cheers,

trent

I don't believe this is a trigger wheel issue.

Sounds like you have the power sequencing incorrect. Check your ECU documentation for proper power connections. Normally an ECU will need to be wired so that it sees power, and controls another relay that turns on power to external devices like coils. Or a separate ignition switch is used, so the ECU is powered from the master switch, and the ignition is enabled later. Some ECUs consider the ignition switch a Run/Stop that enabled the coils outputs.

The Link should have no problem with the 36-1 trigger wheel, and switching to a 12-tooth wheel would certainly be a downgrade in capability.

Thanks for your reply David.

i will check those things you have suggested.

can I ask why you say switching to 12 teeth would be a down grade in capability?

As per Davids comments, it is very unlikely a trigger issue. The link will have no drama with the 36-1 provided the sensor is suitable (many generic industrial hall effect sensors arent suitable for missing tooth wheels).

The 12 tooth is a downgrade as the ECU gets lees updates per revolution so the timing will be less precise. The most noticeable effect is generally during fast transients you will see more timing drift with less teeth.

I have seen the "spark during bootup" with some older ECU's like DTA, Haltech E6, Motec M4 etc but I have never seen it with a recent Link. I think general cause in the old days was if the coils have power before the ecu has fully booted up, the ignition drives were permanently pulled up or floating for a few milliseconds until the ecu booted up and then switched the ignition drives low. The common fix was to have the ignition relay triggered by the fuel pump relay (the fuel pump relay cant get a trigger until the ecu has booted up).

As I say, I have never seen that happen with a Link as I think the ignition pull-ups disabled during bootup but that is the only explanation I can put to it.