charlie_pank Posted July 21, 2003 Share Posted July 21, 2003 My friend and I have made me an adaptor so the my Emerald can use my EU3 wiring loom, so I can finally try and figure out which sensor's playing up and causing a very rough idle /occasional stall on idle when using the rover mems... These are the symptoms: Coolant sensor reading appears to be correct Air manifold temp sensor appears to be at least 15 degrees C too high (ie reading 40 yesterday when in open air outside manifold) However, I've tried to start the engine in 3 different ways: 1. With both sensors plugged in - result = coughs splutters and dies fairly quickly 2. With air temp sensor unplugged - result = same as 1 above 3. With coolant temp sensor unplugged - result = starts first time If it is a problem with the reading of the AIR temp sensor (given that it seems to be reading much too high) why is it that the engine refuses to run until I unplug the COOLANT sensor? Charlie'n'Kermit The plan is: Fit an emerald so I can find out why Kermit's overfuelling S5EVN Edited by - charlie_pank on 21 Jul 2003 11:42:08 Link to comment Share on other sites More sharing options...
Peter Carmichael Posted July 21, 2003 Share Posted July 21, 2003 The coolant sensor corrections are much larger than the air sensor ones. When you default the coolant input it is making a large correction in the right direction and so the engine runs. When you default the air temp sender, the corrections applied will not be as large and may not be noticeable. It sounds like you haven't got to the bottom of this yet. I presume you did reset the MEMS by the old: ign on, open and close throttle fully 5 times, ign off... etc. Edited by - Peter Carmichael on 21 Jul 2003 10:20:50 Link to comment Share on other sites More sharing options...
charlie_pank Posted July 21, 2003 Author Share Posted July 21, 2003 Thanks Peter, I was beginning to worry no-one would reply! The original problem was with the Rover Mems, a very rough idle and coking of lambda probe and spark plugs. I replaced lambda probe which fixed it for about 100 miles, til that one got coked up too! I have now got an emerald so that I can see the temp sensor readings. Although the air temp sensor seems to be reading too high, and the coolant temp sensor seems to be reading true (judging by the dashboard temp readout, compared with the Emerald - PC readout). The behaviour does suggest that the coolant sensor is the one telling porkies, this is backed up by your statement that coolant adjustments are much larger than air temp adjustments. I'm going to try plugging in the coolant sensor once the engine is running to see what difference it makes, and also try running it with no coolant sensor AND no air temp sensor. If this works then I will just have to accept that the coolant sensor is the one at fault, even though it doesn't look like it in the Emerald readout. Maybe it's only out by about 10 degrees - could that be enough to cause the symptoms? Charlie'n'Kermit The plan is: Fit an emerald so I can find out why Kermit's overfuelling S5EVN Link to comment Share on other sites More sharing options...
Peter Carmichael Posted July 21, 2003 Share Posted July 21, 2003 The behaviour does suggest that the coolant sensor is the one telling porkies, this is backed up by your statement that coolant adjustments are much larger than air temp adjustments Sorry Charlie but that wasn't what I was saying. I was merely suggesting that the air temp corrections might result in barely noticeable changes to fuelling whereas the difference between the coolant temp plugged in and reading correctly and defaulting the sensor would likely result in a noticeable change; in your case this change was in the right direction. Instead of comparing the sensor readings to the dash gauge (which I wouldn't trust unless using something like Stack or SPA gauges/senders) try and confirm the correct *characteristics* for the coolant sender. If the engine starts up and cames up to temperature, the rate of climb of temperature is pretty consistent. When it reaches the thermostat opening temperature, the temp climb flattens off until all the coolant in the radiator circuit has been brought up to temperature as well. The temp will then start to climb again. This is a notable characteristic of the cooling system and you can use it to sensecheck a sender reading. I know also that starting and running your engine is a problem at the moment, so this might not be the most helpful suggestion. You could also demount the sender and use it to sense some boiled water... etc. I'm a bit concerned that you are having to resort to unplugging senders that appear to be working and that you are building a hypothesis based on only a little information. Best of luck in getting to the bottom of it though - sound sliek you ar ebeing resourceful. Link to comment Share on other sites More sharing options...
charlie_pank Posted July 21, 2003 Author Share Posted July 21, 2003 If it's not the coolant sensor (under investigation) and it's not the air temp sensor (doesn't make enough of a difference when defaulted) what else could it be - is there a MAP sensor, if so - where? Charlie'n'Kermit The plan is: Fit an emerald so I can find out why Kermit's overfuelling S5EVN Link to comment Share on other sites More sharing options...
Peter Carmichael Posted July 21, 2003 Share Posted July 21, 2003 MAP is inside the MEMS Ecu itself and is fed with a vacuum hose that picks up from the plenum side of the throttle body. Link to comment Share on other sites More sharing options...
charlie_pank Posted July 21, 2003 Author Share Posted July 21, 2003 I'll have a look for a vacuum tube coming out of the manifold, but there's definately no vacuum tube going into the Rover EU3 Mems or the emerald, so the sensor must be somewhere else. BTW. Would I be right in thinking you're the kind of person who fixes this kind of stuff for a living (albeit on much more powerful engines)? If I can't figure it out, would you have a look at it for me (in professional capacity of course), or can you suggest anyone close to SE London who would? Charlie'n'Kermit The plan is: get a new engine 'cos I'm bu$$ered if I know why this ones not working S5EVN Edited by - charlie_pank on 21 Jul 2003 13:57:56 Link to comment Share on other sites More sharing options...
simon_h Posted July 21, 2003 Share Posted July 21, 2003 Have you got a standard plastic plenum on your engine? If you have, the air temp and the MAP sensor are combined, maybe the MAP part of it is broken?? If this is the case it would go some way to explain why you are over fuelling so much. When the sensor is unplugged along with the coolant one the default limp home values will be good enough to run it. If you have throttles and are running alpha-n then it will just be using the air temp part of it, assuming you have some sort of air temp correction, so it doesnt matter. Link to comment Share on other sites More sharing options...
charlie_pank Posted July 21, 2003 Author Share Posted July 21, 2003 Aha! Yes Simon, I do have the plastic plenum. This is sounding more promising, I wouldn't be at all surprised to learn that the MAP sensor was broken. I'll have a look at the MAP readings when I get home and see if that makes sense. - that would also explain why the air temp sensor is so ******* expensive ~ £50 !! C Charlie'n'Kermit The plan is: get a new engine 'cos I'm bu$$ered if I know why this ones not working S5EVN Edited by - charlie_pank on 21 Jul 2003 15:25:19 Link to comment Share on other sites More sharing options...
Peter Carmichael Posted July 21, 2003 Share Posted July 21, 2003 Hi Charlie, Looks like you're getting to the bottom of your k-series fuelling problems. I'm just a hobbyist rather than a professional, but with a good load of K-series experience. If you want a second opinion I'd be happy to look round, but my experience is more limited for EU3 engines so may not apply. I am however a dab hand at Emerald setup, if you are continuing down that path. Link to comment Share on other sites More sharing options...
simon_h Posted July 21, 2003 Share Posted July 21, 2003 At idle I would expect to see about 300-350 mBar MAP, on standard cams/timing that is. I expect you will be seeing 1100 plus, i.e. more than WOT fuelling. That would soon choke the engine and O2 sensor up. Unfortunatly I fly to the USA on business later on tonight, I think I have a spare tMAP at home somewhere which I can let you have for a few beer tokens, but I wont be here until the beginning of August. If you can wait that long or cant get one mail me around the 3rd and I'll see what I can do to help. Simon Edited by - Simon Hayward on 21 Jul 2003 20:54:51 Link to comment Share on other sites More sharing options...
charlie_pank Posted July 21, 2003 Author Share Posted July 21, 2003 Thanks very much for your help guys, I've found the problem... the IACV. The emerald is incapable of controlling it (which I knew when I bought it) but I had assumed that when I removed the rover mems it was fully closed (and would stay like that as long as the emerald was plugged in). This was a MISTAKE!! The IACV was open so providing a reasonable amount of air-flow at load site 0, this meant that it was running very lean as the ECU was expecting no air from the closed throttle. I figured this out after I saw that removing the coolant sensor changed the injection compensation from 70% to 170, thus allowing it to run with the increased airflow. Peter, having taken an hour or so to map the emerald at idle and seeing as it's way too lean as soon as any throttle is applied, I would really appreciate your help if you don't mind. I can provide beer/coffee/pizza/curry if they are adequate incentives... besides, how could you possibly resist the opportunity to learn all about the EU3? - (I don't actually think it's any different apart from the loom and wasted spark). Charlie'n'Kermit The plan is: Map the emerald so it can drive as well as idle S5EVN Link to comment Share on other sites More sharing options...
Peter Carmichael Posted July 21, 2003 Share Posted July 21, 2003 Edited by - Peter Carmichael on 21 Jul 2003 23:29:05 Link to comment Share on other sites More sharing options...
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