AJ16 engine runon

I recently acquired a gorgeous 96 VDP that had been stored for quite a while, well
over a decade actually. It starts and runs fine & getting better the more I drive it.
The problem is that it tends to diesel after the ignition is turned off. It will sit there and
chug away until the key is removed from the ignition switch.
Anyone have a suggestion as to the cause and corrective action on the matter?
All replies welcome & appreciated.

Earl Kiker

Not sure how that can happen with FI, with a carb the engine can continue to draw fuel in and hot spots in the cylinder head can keep igniting the fuel.

I only ever experienced that with carburetted engines. You would think there have to be multiple faults with a fuel injected engine. Maybe the injectors aren’t sealing properly and are dripping. I wonder why pulling the key out of the ignition would stop it dieseling?

May be a fault in the ignition switch - Jim Butterworth mentions something about this in connection with a non starting issue:-

We all get used to thinking of the switch only working in a rotary fashion, but it doesn’t. The lateral part of its movement (along the barrel axis) has a switching function too, and for sure that function switches power to things like the electric seat entry function, i.e. before the key is rotated to the first position.

Often, one of the relays behind the RH front headlights stays live all the time if this part of the switch is not cutting the power, draining the battery. If this relay remains closed, the ECU thinks the engine is still running so the car won’t start.

Sometimes it is only necessary to remove the switch and free up the lateral function with WD 40 or similar, unless the spring is broken, in which case you’ll need another switch.

Just a thought.


What you DON’T want to do is try to free up the switch by inserting the extension tube into the ignition switch, the little trap door likes to hold onto it, ask me how I know :imp:

Try cleaning the butterfly plate in the throttle body first
If it sat that long does the pedal stick just a hair?
Amazing how an aj16 after ten years just drives on and on
If pedal sticks a hair clean the butterfly I think you will be done!

Thanks so much for bringing that to my attention! I have had that very thing in the back of my mind for several days. I’ll do that tomorrow & see if it helps with this and a couple of other minor problems.


Final solution to the problem turned out to be a short in the ignition switch. Not only did
it cause engine run-on after being turned off, it resulted in battery drain that caused
battery to go flat after 4-5 days of sitting idle.
All fixed now! Engine shuts down properly & battery okay after several days of sitting.
Thanks to everyone for your advice and council!!.

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