ArkLaTexSC

I have had a developing dieseling issue that is only getting worse recently. Sometimes it will take up to 15, 20 seconds to totally die. It's embarrassing and I'm ready for it to stop.

Does anyone have a suggestion? Could it be my ECU, since I know it needs the capacitors fixed?

kmartinez1

It could be leaking fuel injectors

ArkLaTexSC

Does that happen more than anomalies?

mecheng10

it could be a faulty ignition switch...

SCereal

iTrader: (4)

It's an odd occurrence with a fully ecu controlled car. If you think about the combustion triangle and how each piece is delivered, its hard to imagine it happening without something that keeps power flowing. I'd be inclined to think ignition switch too just because the ECU has to be on to pulse the injectors. leaking injectors could be a possibility too but I wouldn't expect the car to run on for so long since the injectors wouldn't be "firing" at the right time just constantly leaking fuel into the cylinders.

Thats the fuel side of the triangle. The spark side, you either have power firing your plugs or a hot spot in the chamber auto igniting the air fuel mix. I would think you would have more issues than just this if that were the case so that leads up to think there's still power and enough of it to fire off your spark plugs.

Air is always present even with throttle blade closed so not a concern but for it to run for so long after the car is shut down means it has to be either really lucky or still measuring the airflow.

To me, all signs point to the car still having power and thinking it needs to run so probably electrical in nature. Ignition a good place to start. could be ECU I suppose if it wasn't handling the ignition being turned off properly.

how's the car run otherwise? how well does it run while it's dieseling? is it a smooth idle or a really rough coughing sputtering about to die but just keeps going like a crappy old lawnmower?

ArkLaTexSC

It actually runs pretty well. It's got the power and response it should have.

When it is dieseling, it tends to slow down a good bit and sputter as it dies.

SCereal

iTrader: (4)

Is the rest of the car operating normally like the radio and stuff while its doing it or is it just the engine running? That can help isolate ignition switch.

Another thing to check would be to put a noid light on your injectors and see if they're firing when its doing it. that'll isolate leaking vs firing on purpose and clue us in a little more. also can check for spark to see if its plugs igniting or auto igniting.

ArkLaTexSC

Nope, just the engine continuing to go. No radio, steering wheel auto-recesses like normal, etc.

If it helps, my vacuum lines are a bit odd, and I did notice a LOT of heat in the engine bay (though the engine itself isn't running hot).

SCereal

iTrader: (4)

probably not your ignition switch then since everything else shuts off. check your injectors out, put the lights on them and see whats firing and whats not. that'll narrow it down.

matsushima

Old school vehicles would almost always diesel because of ignition timing being too retarded. That random unwanted detonation could cause more heat than normal from the engine. The thing that I don't understand is how a EFI car can have issues that would change the ignition timing and still manage to get fuel to run after being shut off.

Does your car have any codes? On some cars, I could see a combo of things like leaky injectors (fuel) and a bad knock sensor (retard timing) making it diesel, but it seems unlikely since your ignition switch should cut out power.

ArkLaTexSC

Friend with a lot more experience came over and immediately decided it was my vacuum lines....and it was.

SCereal

iTrader: (4)

Wow that's crazy. Wouldn't have guessed vac. Glad you got it squared away. Any explanation of how or why?