Hi. Iv got a series 3, approx 90k on the dash always serviced, recently noticed with the cold weather, startin up in the morn (its freezing at 6:30am) the car kicks over and fires excellent, yet if i turn off the ignition, the entire car shuts off, the dash goes off, and the engine keeps running? verry low quiet idle, probably around 100rpm....its enough to rock the car.... only when its cold though, and about 3/10 times. i am out of ideas, i noticed the timing had been advanced perhaps its out a few degrees. or time to renew the belt any input would be appreciated.
its called dieseling .. oh dear !! http://en.wikipedia.org/wiki/Dieseling Dieseling or engine run-on is a condition which can occur in spark plug gasoline powered internal combustion engines whereby the engine keeps running for a short period after being turned off, due to fuel igniting without a spark. Dieseling is so-named because it is similar in appearance to how diesel engines operate, by firing without a spark. However the ignition source in a diesel is the compression of the gas in the cylinder, while in the dieseling phenomenon the compression ratio is not sufficient to ignite the fuel and it is a hot spot inside the cylinder that starts combustion.
thanks WAZTTED. i just cant understand, why it would run-on even if i shut off ignition prior to running for even a few seconds. like many problems with z'dz especially electrical issues.....time is money, time on a zd is cossssstly. any help is apppreciated. I will add, as the ecu is located passenger floor front, i have had bad door seal leaks in the car, and have had alot of rain lately, the carpet is damp sooo....especialy on that side, moisture and electronics mix like petrol and water lol
never heard of it happening on a z before that for sure... someone hasnt hooked up a dodgy turbo timer have they
its an NA, but i just made sense of it, the ecu's location is right in damp carpet, my door seals are shot and i have had alot of rain, enough to soak the cars carpet over time... on the passengers side...perhaps that has contributed
Running like a diesel engine Last time I saw that happen was on my RZ350 two stroke motor cycle, interestingly enough the throttle got stuck on so I turned the ignition off and pulled over to my surprise it kept running at 10,000 RPM on the rev limiter. I then turned the fuel off and stood back until the carbies drained and stopped the engine (1990). Luckily enough in your case the fuel pump will stop with the ignition off and the engine will only run until there is no fuel pressure in the rail.
yes i gather that, what keeps it dieseling when the engine is cold though....... how can it combust when still cold
Even in this situation it should not run on with an injected engine. Key off = injectors stop pulsing and plugs stop sparking. The only way a petrol engine will run on is if fuel is still getting into the pots and there is a nice little piece of hot carbon around the valves igniting the fuel, or an engine with very high compression ratio.
Your wet ECU is likely the culprit. Water and electronics can produce all sorts of weird and wonderful results.
My mates old Mazda 1000 ute used to do it. Bit weird, had been rebuilt, high comp, but largish cam. Was carby though, every so often he would have to stall it when he parked. Was real rough running though.
i do not know, the engines timing is highly advanced (purchased this way) the car will contiunue to fire and idle cold......electrical issue. i agree ignition off - injectors off......F'ing mistry
a likely answer car may have leaky injectors, which allow a small amount of fuel to seep into the cylinder over time....this extra fuel burns off during the warm up period, so the problem will not occur when warm(no extra fuel in cylinders)....but if the engine is shut down while some cylinders have remaining unburnt fuel, plus the hotspots or ecu playing up caus its wet........you do the maths hehe
My Kombi did the same, but when it was hot, carbon buildup was the culprit. Ran a methanol/water mist through the intakes for a while and it cleaned out the cylinders good and pretty. I'd more look at a static charge due to the wet ecu being the cultprit, take it out, open it up and let it dry out and see if it still happens.
cheers AndyMac, slight moisture in ECU, now it runs sweet again and DRY lol. Thanks everybody for your help
