Bendirk Posted August 2, 2020 Report Share Posted August 2, 2020 (edited) Dear Tr6 experts, Recently the engine of my PI is cp “dieseling.” when I swich off the car. The car runs fine and nothing has changed recently. The wrong ignition may be due to carbon residues, but where does the petrol come from when the Bosch pump is switched off. At the moment I put the gear in 4 th and let the clutch slowly come in to stop the engine. Please advice where to look to cure this problem Thanks and Greetings from Ben Edited August 3, 2020 by Bendirk Quote Link to post Share on other sites
barkerwilliams Posted August 2, 2020 Report Share Posted August 2, 2020 Ben, Is the Bosch pump actually switched off or is it still running? Have you just assumed because the ignition key it turned off then the pump must have stopped? Alan Quote Link to post Share on other sites
Bendirk Posted August 2, 2020 Author Report Share Posted August 2, 2020 Alan, Indeed, I assumed the pump is off . The feed to the relay of the pump is coming from same source as the feed to the ignition. But perhaps the relay is sometimes “ sticky.“ I will do some checking Thanks Ben Quote Link to post Share on other sites
Mike C Posted August 2, 2020 Report Share Posted August 2, 2020 Could be liquid petrol lying in the inlet manifold boiling off when the butterflies are closed. Quote Link to post Share on other sites
Waldi Posted August 3, 2020 Report Share Posted August 3, 2020 Hi Ben, I would also check if the ignition remains energized (with a voltmeter connected to the coil feed) at the moment of switching off. Groetjes, Waldi Quote Link to post Share on other sites
Paul J Posted August 3, 2020 Report Share Posted August 3, 2020 I have had a similar issue when the electric fan continues to run after stopping and switching the ignition off. Paul Quote Link to post Share on other sites
stuart Posted August 3, 2020 Report Share Posted August 3, 2020 47 minutes ago, Paul J said: I have had a similar issue when the electric fan continues to run after stopping and switching the ignition off. Paul We have discussed this before I believe, fan generates enough current to ignite any unburnt fuel Stuart. Quote Link to post Share on other sites
barkerwilliams Posted August 3, 2020 Report Share Posted August 3, 2020 Ben, Does the engine only run on when the cabin fan is off? Next time the car is running on then please humour me by turning the wipers on. Did the engine stop? Alan Quote Link to post Share on other sites
Bendirk Posted August 6, 2020 Author Report Share Posted August 6, 2020 I measured some things. When I turn off the key I immediately measure 0 (zero) volts on the ignition coil the spark plugs therefore cannot spark. No illegal current from the fan and wiper motor. Fuel pump also stops. Relay is burned in, it may stick sometimes. Now testing with a new one. Thanks for the tips the story continues Ben Quote Link to post Share on other sites
Mike C Posted August 6, 2020 Report Share Posted August 6, 2020 How long does the engine run on for if you don't stall it? Quote Link to post Share on other sites
Bendirk Posted August 6, 2020 Author Report Share Posted August 6, 2020 Hi Mike Just a few seconds with terrible Diesel sound Greetings Ben Quote Link to post Share on other sites
Waldi Posted August 6, 2020 Report Share Posted August 6, 2020 Hi Ben, You could try to push your gas pedal a bit when stopping the engine. This will lean the mixture. Using petrol with a higher octane will also help. Waldi Quote Link to post Share on other sites
Bendirk Posted August 6, 2020 Author Report Share Posted August 6, 2020 Hi Waldi I give it a try. Using Shell V Power Ron 98. Greetings Ben Quote Link to post Share on other sites
John L Posted August 6, 2020 Report Share Posted August 6, 2020 As a matter of interest which plugs are using? John Quote Link to post Share on other sites
ntc Posted August 6, 2020 Report Share Posted August 6, 2020 Remember the word decoke it in the service guidance Quote Link to post Share on other sites
SpitFireSIX Posted August 7, 2020 Report Share Posted August 7, 2020 (edited) Hi, Two separate posts way above sound like alternator powering an additional ignition power relay. A diode bPut an end to that nuisance. Sounds like running on as something is still igniting fuel. Edited August 7, 2020 by SpitFireSIX text Quote Link to post Share on other sites
Mike C Posted August 7, 2020 Report Share Posted August 7, 2020 Or the fuel is still in the combustion chambers and available to be ignited. Quote Link to post Share on other sites
Waldi Posted August 8, 2020 Report Share Posted August 8, 2020 Hi Ben, Can I suggest you have a look at the plug fouling topic that is currently going? I certainly learned from that (but do not have any issues at the moment. Cheers, Waldi Quote Link to post Share on other sites
Bendirk Posted August 8, 2020 Author Report Share Posted August 8, 2020 (edited) John I have Bosch WR7DTC installed up to now no problems. Sorry must be W7LTCR Greetings Ben Edited August 10, 2020 by Bendirk Error in typing Quote Link to post Share on other sites
Z320 Posted August 8, 2020 Report Share Posted August 8, 2020 (edited) Hi, it's me, the guy with the stupid questions and different opinion. Sorry me for asking myself (and you) something about a 6 PI without knowing anything about this engine. "Dieseling" is a not controlled ignition? This is the case with the ignition switched off? Yes. But the still running fan produces voltage to suply the ignition? Yes. Then, with the ignition still suplied with voltage, and still working - why is there a NOT controlled ignition? Ciao, Marco Edited August 8, 2020 by Z320 Quote Link to post Share on other sites
Waldi Posted August 8, 2020 Report Share Posted August 8, 2020 Not a stupid question Marco. let’s wait for the answer, from people who know. my car has an electric fan, but it stops immediately after switching off. Guess the wiring diagram around the ignition barrel provides the answer. Waldi Quote Link to post Share on other sites
Nigel Triumph Posted August 8, 2020 Report Share Posted August 8, 2020 If the cooling fan is wired through the ignition switch, when the ignition is switched off when the fan is running, the momentum of the fan blades will keep the fan motor turning for a few seconds. During this short period of time, the fan motor can act as a dynamo, providing current to the ignition circuit. This may be enough to produce sparks and keep the engine running. However, the fan should quickly stop, then the current stops and with no more sparks, the engine should stop. I can't see how the cooling fan could supply enough current to run the ignition for more than a few seconds. Wiring the fan via a relay is recommended, to reduce the load on the ignition switch. Wiring via a relay should also prevent the turning off the fan from energizing the ignition circuit. Others with more electrical expertise will be able add to my basic explanation. Nigel Quote Link to post Share on other sites
SpitFireSIX Posted August 8, 2020 Report Share Posted August 8, 2020 4 hours ago, Z320 said: Hi, it's me, the guy with the stupid questions and different opinion. Sorry me for asking myself (and you) something about a 6 PI without knowing anything about this engine. "Dieseling" is a not controlled ignition? This is the case with the ignition switched off? Yes. But the still running fan produces voltage to suply the ignition? Yes. Then, with the ignition still suplied with voltage, and still working - why is there a NOT controlled ignition? Ciao, Marco Hi, If no additional relays have been added to the ignition circuit, a decelerating cooling fan can not supply the energy to fire the plugs. So, I do not believe what you describe is possible. Yes I have heard this myth before. Quote Link to post Share on other sites
Mike C Posted August 8, 2020 Report Share Posted August 8, 2020 4 hours ago, Z320 said: Hi, it's me, the guy with the stupid questions and different opinion. Sorry me for asking myself (and you) something about a 6 PI without knowing anything about this engine. "Dieseling" is a not controlled ignition? This is the case with the ignition switched off? Yes. But the still running fan produces voltage to suply the ignition? Yes. Then, with the ignition still suplied with voltage, and still working - why is there a NOT controlled ignition? Ciao, Marco I agree Marco. If the ignition system is supplied with a current, from whatever source, it still controls the engine firing. The engine running should be as normal. There should be no uncontrolled diesel "knock" as happens with preignition. Quote Link to post Share on other sites
Z320 Posted August 9, 2020 Report Share Posted August 9, 2020 (edited) Why switch off the ignition on a PI? There is no reservoir like the float chambers on carburetors? I would test to switch off the fuel pump WITH the ignition ON. This way I expect a controlled ignition until the engine stops because of no fuel. BUT - as I told before - I know nothing about the PI, you PI guys have to find out. Wishing you much success Edited August 9, 2020 by Z320 Quote Link to post Share on other sites
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