Cranks but won't fire
 

Hey team,

I have a supercharged (sprintex) GT86 running Ecutek. Car's been running great for years. But I only run it once a week, sometimes not even that.

The other day I moved it out of the garage to clean it. I turned it on and drove it out of the shed a few metres. Turned it off. Cleaned it (inside) and then put it back.

I was then away for the next 4 days. When I came back it wouldn't start.

Cranks over, just no fire. I feel like there was a small stumble the first time like it was going to start but that hasn't happened again since. I get about 4 goes at starting it before the battery starts to die.

I've tried starting it with jumper cables but that didn't help. In fact, the battery still went flat trying which I thought was a bit odd. Must take a lot of juice to crank it.

I've tried starting it with my foot on the accelerator to the floor in case it was flooded. Although I think the fuel would have evaporated while I was away.

I've tried spraying a bit of 'Engine Starter' in the intake, and into a vacuums tube before the supercharger.

What is next? I'm wondering if running it so briefly might have fouled up my plugs. But I would have expected it to at least stumble or run rough with dirty plugs. Is this a common problem?

If it won't start on ether then you don't have spark. Check all your grounds of course then maybe sensors starting with crank position

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I forgot to mention the Ecutek app isn't showing any DTCs. I would have expected something like a crank position sensor to report a fault code?

How does one go about testing the crank position?

Can you do a "trigger test" through ecutek? My standalone will let me do that. Start test, crank, look at results. It graphs the crank, cam, and coil pulses. Otherwise pull it out and look online how to test a crank sensor. Not sure if it's a Hall effect or not though

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I like this observation. How old is the battery? Do you have, or are you willing to get a charger?

If you don't want to go through the hassle of getting a charger, just swap batteries between cars. Otherwise disconnect the battery and, while it's out, step on the brake pedal for a few seconds. (brake lights) to drain the filter caps in the ECU.

I suspect that the ECU got jammed up with the brownout you gave it the first time.

The battery is a bit old and shit. I have a battery charger.. and I charge it up of course.
When it is charged up it will let me do continuous cranks until the ECU cuts off. And it will allow me to do that about 4 times before it starts sounding flat.

But even if the battery was a bit crappy it should still start.

I have no idea what you're talking about draining filter caps in the ECU.. or how these got jammed up. But I will try what you suggest!

Computer stuff. He's not trolling. Caps are capacitors

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Ha ha I did wonder if he was going to tell me to check my flux capacitor fluid next. No I don't think I can do a trigger test with Ecutek. At least, not through the Ecutek Connect BT app anyway.

Got a laptop you can use?

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Yeah I've got a MacBook that I put Bootcamp on so I could run Windows for Ecutek. Not that I know my way around using it really. I only did that to load on the initial tunes. Not even sure if it can do such a test? Google isn't coming up with much.

I imagine there won't be much info. On my unit the trigger test is under a tools tab. I can't imagine the name of the tool could be varied much beyond "trigger test". It might not be included with tuning software since it is covered by tech stream. Worth a shot though. As long as you don't mess with settings or numbers in a table, you won't fuck anything up

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When in standby mode, the ECU draws so little that it can keep the memory floating on the energy stored in the power supply filter caps for quite a while. Stepping on the brakes drains them and ensures a full reset of the temporary learned stuff which can be corrupted by a brownout. Not saying that's it but at least you'll be able to rule it out. The effect is real. I've read about it here many times.

Interesting.. what is a brownout?

Anyway I tried it and it didn’t help. After a few more goes with a bit of ether I managed to get one more very brief stumble.. a tiny something but nothing more.

Supply voltage drop. If the starter struggles, lights dim, blah blah...

Well, at least it's a hard failure somewhere. Sounds like you have spark. Do you hear the main fuel pump run when first turning on ignition? Fuses all good?