Pierre Gillet Posted May 24, 2005 Share Posted May 24, 2005 My mate Serge is still struggling with a Seven whose engine does not cut off when the ignition switch is turned off. He is now suspecting the MFU which is of the 'old model' (according to the excellent angus&tessa site), car is 1997. He would like to order one from Rover. They need a reference. There is no apparent tag on his MFU. Can someone help ? Edited by - Pierre Gillet on 24 May 2005 21:28:41 Link to comment Share on other sites More sharing options...
Pierre Gillet Posted May 25, 2005 Author Share Posted May 25, 2005 😬 Pierre Link to comment Share on other sites More sharing options...
caterhamnut Posted May 25, 2005 Share Posted May 25, 2005 Hi Pierre - I got an email from Serge - I am trying to find out what i have and will get back to him asap. Big update! here 80,000miles in 3 years plus Link to comment Share on other sites More sharing options...
Colin Mill Posted May 25, 2005 Share Posted May 25, 2005 Hi Pierre Is this not the problem that is caused by the cooling fan (or heater fan) acting as a generator after the ignition has been turned off? (TADTS) Colin Link to comment Share on other sites More sharing options...
Pierre Gillet Posted May 25, 2005 Author Share Posted May 25, 2005 Thanks guys Colin, this is very interesting. I shall pass the info to Serge. Cheers Angus and Colin ! Pierre Link to comment Share on other sites More sharing options...
Colin Mill Posted May 25, 2005 Share Posted May 25, 2005 Hi Pierre If Serge wants a fix for the run-on I have one that I'm going to fit once I get my car back from CM. It just involves powering each of the two fan motors via schottky diodes. This blocks the back EMF of the motors from driving the ECU when you turn off. To be on the safe side I'm going to double up on the diode feeding the cooling fan so one diode could fail and still leave you with a working fan. Colin Edited by - Colin Mill on 25 May 2005 20:38:00 Link to comment Share on other sites More sharing options...
Pierre Gillet Posted May 25, 2005 Author Share Posted May 25, 2005 Thanks Colin I figure that the motors need to be running to be able to act as generators ? In fact Serge is experiencing the problem with a cold engine and a heater fan not running *confused* Pierre Link to comment Share on other sites More sharing options...
Colin Mill Posted May 25, 2005 Share Posted May 25, 2005 Hi Pierre Most odd! Since the ECU needs quite a bit of power to operate the injectors and produce the sparks its amazing that it manages to run on with no apparent power source - perhaps Serge has a diesel 😬 Link to comment Share on other sites More sharing options...
Colin Mill Posted May 25, 2005 Share Posted May 25, 2005 More seriously though - do you know about how long the run-on lasts? Also does Serge have any non-standard bits of electrical stuff fitted to the car? It would be interesting to connect an LED in series with about a 1k resistor across the switched side of the ignition and look if it goes out sharply when you turn off or goes out gradually. Link to comment Share on other sites More sharing options...
Pierre Gillet Posted May 25, 2005 Author Share Posted May 25, 2005 It seems that the relays do not get from the ECU the cut off signal...if he uses his ignition switch. If he takes the ECU fuse out, the engine stops. Pierre Link to comment Share on other sites More sharing options...
Pierre Gillet Posted May 25, 2005 Author Share Posted May 25, 2005 Colin your last proposal is troubling since there actually was a diode on one of the white leads (switched side of the ignition button) probably inserted by the former owner. Serge did not insert it again when he installed a on/off helicopter style ignition switch and a starter push button. here Pierre Link to comment Share on other sites More sharing options...
Colin Mill Posted May 25, 2005 Share Posted May 25, 2005 Sorry Pierre - I should have looked at the wiring diagram closer. There is an unswitched feed to the ECU (via fuse 14) so I guess this provides the injector and ignition power. That explains part of it. I'll look a bit more at the diagrams and get back to you Link to comment Share on other sites More sharing options...
Colin Mill Posted May 25, 2005 Share Posted May 25, 2005 Yes, that diode looks exactly the sort of thing. Perhaps its worth dropping it back in. If the ECU relay is really low current then perhaps a decoupling capacitor on the input side of some bit of electronics on the car could hold the relay in for long enough to cause the problem. At a guess the overun does not happen with the headlights on - am I right? Link to comment Share on other sites More sharing options...
Pierre Gillet Posted May 26, 2005 Author Share Posted May 26, 2005 Thanks Colin. I passed on the info to Serge sometimes with a quick translation. He definitively should apply for membership to the Club to be able to post 😬 Pierre Link to comment Share on other sites More sharing options...
Pierre Gillet Posted May 26, 2005 Author Share Posted May 26, 2005 The Rover reference for a 1600 K 1997 MFU is YWB 10022. With a a new ECU/Immobilizer and a new MFU the problem is still there: the engine cuts off in 2 mn of time with his old MFU and 4 mn with the new one. Serge has still not bought the LED and resistor but plans to do it presently. Hi Colin, the overun does happen with the headlights on Pierre Edited by - Pierre Gillet on 26 May 2005 20:41:43 Link to comment Share on other sites More sharing options...
Colin Mill Posted May 26, 2005 Share Posted May 26, 2005 Ok - its certainly a tough one. That's one hell of an over-run time as well! The only additional info I have is from a Rover circuit diagram. When the MEMS ECU is fitted to a Rover Metro the feed to ECU plug 2 pin 80 seems to be switched by a relay. In the Caterham this feed is unswitched. So on the Metro the relay does the equivalent of pulling fuse number 14 (which I seem to recall you said stopped the over-run) Colin Link to comment Share on other sites More sharing options...
Pierre Gillet Posted May 27, 2005 Author Share Posted May 27, 2005 Seems to me that this info could be very valuable. Thanks for it. I pass it on to Serge. Cheers Colin! Pierre Link to comment Share on other sites More sharing options...
Pierre Gillet Posted May 28, 2005 Author Share Posted May 28, 2005 Serge finally had his car looked after by the Rover garage of Chambery. Their electrician solved the problem. At this time we still do not know how, but we keep you posted as soon as possible. Many thanks for your help guys *thumbup* Cheers, Pierre Link to comment Share on other sites More sharing options...
Colin Mill Posted May 29, 2005 Share Posted May 29, 2005 Pierre I'm glad its sorted - I look forward to hearing how it was fixed. Link to comment Share on other sites More sharing options...
Pierre Gillet Posted May 30, 2005 Author Share Posted May 30, 2005 OK Serge has now the explanation from the Rover electrician: It seems that a small loss of current on the windscreen electric heating was feeding the ECU through the positive lead after ignition under a 2 Volt tension.So the ECU was not getting the signal that ignition was off when the ignition switch was turned off and was not triggering the main relay which was quite normally staying closed until consumption of this current which would take about 2 minutes. The first owner had used a diode to avoid the 2 V current feeding the ECU. Hope it is clear My question is : how can a resistor (the windscreen electric heater) accumulate current ? Pierre Edited by - Pierre Gillet on 30 May 2005 20:56:54 Link to comment Share on other sites More sharing options...
Colin Mill Posted May 31, 2005 Share Posted May 31, 2005 Pierre Yes, I too wonder how the screen heater could have the effect described unless its acting as a radio antenna and you are near the Droitwich transmitter 😬 Link to comment Share on other sites More sharing options...
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