Engine Won't Turn Off After Battery Went Flat And Jump Started It

[dan.1337]

I left an interior light on in my R33 which unfortunately drained my month old battery completely. I've jump started it a hundred times before on my old battery as it died every few days, but this time I was careless and hooked up the wrong cables on the jump pack (black-red, red-black instead of black-black, red-red).

I recognised this error after my jump pack started beeping at me, so I swapped the cables around, jump started it, and took it for a drive.

When I turned it off, the car just kept running. All electronics and the turbo timer was shut off but the engine continued to run. Since then, I've had to use my fuel pump kill switch to turn my car off.

I checked all my fuses (bonnet, cabin, boot) and none appear to be blown. Something else I've noticed is that my central locking using my remote still works, but the immobiliser "beep" doesn't sound anymore when I lock and unlock my car.

I disconnected the battery for an hour yesterday but it didn't seem to help, so I pulled the battery out completely and have put it on a charger to pump it right up.

Do you guys have any ideas my engine might not be switching off when I turn the rest of the car off?

Unfortunately Google and search hasn't helped much this time around.

[KiwiRS4T]

No 1 ditch the turbo timer.

[dan.1337]

No 1 ditch the turbo timer.

Been meaning to do that since I bought the car but haven't got around to it. It's always been set to 0 seconds so the car switches itself off straight away anyway.

[tridentt150v]

ECU issue is my guess. When you disconnected the battery did you hit the brakes and/or turn the headlights on? Just to absolutely drain the system.

[dan.1337]

ECU issue is my guess. When you disconnected the battery did you hit the brakes and/or turn the headlights on? Just to absolutely drain the system.

Potentially an ECU issue, but the engine still runs like usual when it's on?

I didn't hit the brakes or anything. It was completely drained when I got to it as it was just the little reading light on.

[tridentt150v]

When you disconnected the battery I meant - was it completely drained when you disconnected.

Anyway the spark from connecting jumper leads can be damaging to ECU's. You may have to source another one if its standard, if its aftermarket [apexi, haltech,link etc] then they may be able to repair it, not sure.

[dan.1337]

When you disconnected the battery I meant - was it completely drained when you disconnected.

Anyway the spark from connecting jumper leads can be damaging to ECU's. You may have to source another one if its standard, if its aftermarket [apexi, haltech,link etc] then they may be able to repair it, not sure.

In that case, I didn't pump the brakes or turn on any lights. I have pulled the battery out of the car completely since then to put it on a charger though, so it should be well and truly dead by now.

Because I used a jump pack there was no spark. I connected the leads then turned the pack to "on", then turned it off after it started beeping because the leads were crossed.

I have a PFC and will get my mechanic to check it out if I can't find the cause myself.

[jiffo]

Why do guesswork?

Remove the turbo timer first and then see how she goes.

If it's any decent brand it will have a patch harness that simply plugs/unplugs into the stock harness, 5 seconds work.

After that I'd check the ECCS and IGN relays. (both beside the ECU)

But get rid of the timer before you start worrying about a fried ECU.

[dan.1337]

Why do guesswork?

Remove the turbo timer first and then see how she goes.

If it's any decent brand it will have a patch harness that simply plugs/unplugs into the stock harness, 5 seconds work.

After that I'd check the ECCS and IGN relays. (both beside the ECU)

But get rid of the timer before you start worrying about a fried ECU.

Great, thanks for this. It's a branded turbo timer (Apexi from memory) so I'll try the above tonight.

[Duncan]

Why do guesswork?

Remove the turbo timer first and then see how she goes.

If it's any decent brand it will have a patch harness that simply plugs/unplugs into the stock harness, 5 seconds work.

After that I'd check the ECCS and IGN relays. (both beside the ECU)

But get rid of the timer before you start worrying about a fried ECU.

Yeah exactly, it will almost certainly be directly unplugable, just follow the large wires and plug from the back of the ignition key. All it would take is something minor in that not being protected by a fuse to melt to open and cause this.

If not, I'd check (ie swap) the ECCS relay before worrying too much about the ECU having an issue, it might also have failed to always on

[dan.1337]

Thanks for all the suggestions.

I'd been meaning to pull out the turbo timer for a long time and this was a better time than ever to do it. Was piss easy (not sure why I didn't try earlier), and now everything is rosy again.

Car turns right off and the immobiliser is back online.