tiddy1 Posted July 15, 2004 Share Posted July 15, 2004 When I switch off my K-series it will run on for up to 10 seconds with the ignition key totally removed, any sugestions why? my thought is that I have leaking injectors? it sis a 200 bhp ex VVC engine running TBDS and an emerald. however it use to do it prior to converting to emerald Simon Link to comment Share on other sites More sharing options...
Sue Dinnim Posted July 15, 2004 Share Posted July 15, 2004 Sorry I can't answer the question but I will be interested in the answers as I occassionally have the same trouble. Standard 1.6 KSS Someone did once suggest it could be down to the timing but it is an intermittent problem in my case so therefore unlikely. Could it be differing fuels? Link to comment Share on other sites More sharing options...
Nev Posted July 15, 2004 Share Posted July 15, 2004 I've read on here that it's to do with the Cooling fan running at the time you switch off the Ignition. This acts as an generator for a short period and keeps it running. I have had the same thing happen on my K-series SV Hopes this helps Nev Link to comment Share on other sites More sharing options...
Peter Carmichael Posted July 15, 2004 Share Posted July 15, 2004 This only happens when the radiator fan is running. Link to comment Share on other sites More sharing options...
Graham King Posted July 15, 2004 Share Posted July 15, 2004 I have the same issue (1.8Kss), I may be imagining it but the car seems to run on when the radiator fan is running, whereas if fan not running car seems to stop immediately. Is the fan ECU switched (or does it inform ECU that it is running) or is it direct from stat 🤔. I always wondered if this was something to do with it. Not really answered question but has anyone else noticed any correlation. R7 GPK Superlight #85 Link to comment Share on other sites More sharing options...
Peter Carmichael Posted July 15, 2004 Share Posted July 15, 2004 It is just the bodged up wiring loom that doesn't pull the ignition circuits to ground. It could be classed as a fault and under MSA rules would be inadequate as the only method of stopping the engine as it is not guaranteed to stop the engine immediately. Link to comment Share on other sites More sharing options...
Chris W Posted July 15, 2004 Share Posted July 15, 2004 I concur with the replies above from Nev and Peter. If the radiator fan is running at switch-off it acts as a generator and holds its supply line high for a few seconds. The ECU will work down to about 6v so the ECU doesn't "know" you've switched off until the output from the radiator fan drops below this value. Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
John Howe Posted July 15, 2004 Share Posted July 15, 2004 ... they all do that, sir! It is being fed from the radiator fan. When the fan is not engaged it will not happen. JH Deliveries by Saffron, the yellow 222bhp Sausage delivery machine Link to comment Share on other sites More sharing options...
old captain slow Posted July 15, 2004 Share Posted July 15, 2004 Isn't it the Lambda sensing unburnt fuel in the exhaust and as it's expecting a cat to be present won't stop the engine until the fuel is used up? Can't imagine the cooling fan having enough inertia to run the engine for several seconds. Also in my K the fan stops the instant the ignition is switched off but the engine can carry on for a while. Either way they all do it and it stops after a bit. 😬 C7 CDW Link to comment Share on other sites More sharing options...
Peter Carmichael Posted July 15, 2004 Share Posted July 15, 2004 Your lambda theory isn't viable - it even happens with an Emerald not using the lambda input. It is related to the fan running. I like the lambda theory however, but not nearly as much as I like the leaky fuel injectors theory. Link to comment Share on other sites More sharing options...
tiddy1 Posted July 15, 2004 Author Share Posted July 15, 2004 This seems to happen when the fan is not running, so that blows that theory. but the ecu not going to ground seems more likely. Pete why don't you like my leaking injector theory. Simon Link to comment Share on other sites More sharing options...
Chris W Posted July 15, 2004 Share Posted July 15, 2004 David I have an LED across the supply line to my fan so that I know it is indeed switching on and off occasionally whilst running. When I switch off with the fan running, the LED stays bright for quite a few seconds and then fades slowly. This is a direct indication that the supply line is being held high temporarily. Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
Myles Posted July 15, 2004 Share Posted July 15, 2004 'Interestingly' - after wiring in Chris W's override switch and LED, you can see the LED light weakly in lowish light conditions when pressing on... I guess this just goes to show that my radiator isn't blocked externally.... Keep BC free and open for ALL. Membership No. 43xx Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Colin Mill Posted July 15, 2004 Share Posted July 15, 2004 If it is the fan that's responsible we could cure it by putting a suitable size diode in series with the fan. Does anyone know what the start-up current for the fan is as we would need to spec the diode to cope with that initial load. Colin Link to comment Share on other sites More sharing options...
grumpy the 7th Posted July 15, 2004 Share Posted July 15, 2004 I agree with the 'fan running' theory. I too have a LED accross the fan feed & yes that slowly fades out if the fan is running. (thanks ChrisW it was your email about the switch with built in led that gave me the idea) *thumbup* rog C7 TNT (Honda Irish Green and Peugeot Graphite grey - it's dynamite) http://www.seven-ecstasy.co.uk/html/stoneleigh04_64.html Link to comment Share on other sites More sharing options...
Chris W Posted July 15, 2004 Share Posted July 15, 2004 Colin The start-up current is around 10A (hence the 15A fuse) with a running current of around 6A. You will drop around a volt across a high-power diode so the power P to the fan (and therefore its speed) will decrease by about 20% (P is proportional to V squared). This may or may not affect the cooling effectiveness. The diode would need to handle about 15W to be sure it doesn't burn out. I suggest a heat sink for it if you want to go this route. Remember, though, you are adding another point of potential failure. If the diode burns out, the fan will not run at all with far more serious consequences. An alternative solution, that won't affect the fan speed, would be to insert a high-power resistor across the fan which will short the "generated" current to ground at switch-off. However, the resistor will have a quiescent current through it of (V^2)/R where V = 14v with the engine running. The smaller the resistor the faster the fan will stop but the more quiescent current through the resistor and hence the greater the power dissipated. I would suggest experimenting with resistors in the range 1 ohm to 10 ohms. Use a ceramic type on a heat sink. So with a 1 ohm resistor the power disssipated will be 200W (all the time)!!! With a 10 ohm resistor this will drop to 20W. To dissipate this much power I would suggest using a chain of resistors in series (say 5 x 2 ohm resistors with each one therefore dissipating 4W). The best solution of all, IMHO, is just to live with it. It's only a couple of seconds. Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
Colin Mill Posted July 15, 2004 Share Posted July 15, 2004 Hi Chris Yes, I'm not likely to do anything to 'cure' it on mine - some of the old air-cooled VWs would still be running when you left the car park so its not likely to get on my nerves. For those that want to try, a Schottky barrier rectifier would be good as with something like an IR 47CTQ030 you would only be loosing 0.3v across the device at 6amps. The dissipation would be a bit lower too (under 2W) so the heat sink would be easier to organise. They come out at only about 2 quid even from RS 8-) Best regards Colin Link to comment Share on other sites More sharing options...
Peter Carmichael Posted July 15, 2004 Share Posted July 15, 2004 Shurely you just arrange the ignition switch as a switchover, linking a resistor into the ignition circuit pulling the circuit to ground. Link to comment Share on other sites More sharing options...
Chris W Posted July 15, 2004 Share Posted July 15, 2004 Peter Yes but..............The standard 7 ignition switch doesn't have a contact in the OFF position. One would have to ensure that with a toggle switch ignition, one had an SPDT (or a DPDT) to be able to do this. Given this, the method would work fine. Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
old captain slow Posted July 15, 2004 Share Posted July 15, 2004 Next time I get the old girl out I'm going to run some tests re the "fan club". To see what happens. C7 CDW Link to comment Share on other sites More sharing options...
Chris W Posted July 15, 2004 Share Posted July 15, 2004 Colin Do you have a website for that particular diode as I can't find it on the RS site nor anywhere else. IR is International Rectifier for the maufacturer but RS don't list that particular model number. Normally, Schottky's have similar Vf's to conventional diodes ie: around 1 volt for high currents. Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
charlie_pank Posted July 15, 2004 Share Posted July 15, 2004 Interestingly, I have a similar problem and am familiar with the radiator fan theory. I think my issue is different though as it does it when the fan isn't on, AND it's only done it since I got an Emerald. It doesn't really bother me, neither does it appear to have done any harm, just a bit odd. Charlie'n'Kermit The plan is: There is no plan S5EVN Link to comment Share on other sites More sharing options...
Mrs Locust Posted July 15, 2004 Share Posted July 15, 2004 The heater fan causes it too Link to comment Share on other sites More sharing options...
Tony C Posted July 15, 2004 Share Posted July 15, 2004 Mine used to continue running if the coolant fan was running, but since I fitted an Emerald it no longer does it - Dave Walker was a little surprised during the rolling road session when it didn't run-on - spooky BRG Brooklands SV 😬 It seems that perfection is achieved not when there is nothing more to add, but when there is nothing more to take away. (Antoine de Saint-Exupery) Link to comment Share on other sites More sharing options...
Colin Mill Posted July 15, 2004 Share Posted July 15, 2004 Hi Chris The Schottky I mentioned is one I found in a last years RS catalogue but I guess they still do it. The RS order code is 357-4100 and they rate it at Vf= 0.38v drop at If=20A. It has a Ifmax of 40A. Its good for a reverse of 30v so assuming none to many inductive nasties from the fan motor I would give it a good chance of surviving. There are others in the series with the usual trade-off of Vrrm and Vf performance. (I just realised I cocked up on the part number in my previous message - sorry. Its actually 42CTQ030 ) Best regards Colin Link to comment Share on other sites More sharing options...
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