chrispot Posted January 7, 2013 Share Posted January 7, 2013 hi david, just another thought, I'am no tuner but from what i have read the ecu at idle alters the timing to contol idle speed quickly rather than an air control device, ignition timing can be changed almost instantly where as an idle vavle will take more time to raise or lower engine speed. I don't know what it could be in your case but you might be able to disable it in the ecu and see if that is your problem? I would'nt know how to sort it. good luck regards chris Quote Link to comment Share on other sites More sharing options...
David P Posted January 7, 2013 Author Share Posted January 7, 2013 (edited) Chris, Thanks for the input, simplest thing I could do that I haven't, is to unplug the knock sensors and see what happens, yet I need to get up-to-speed with the Laptop part of the equation. I have found an error with the electric fan circuit, the thermostat is switching a positive relay signal. I can't see how that could be the problem, but suspicious of temperature related devices, first chance I get will rewire it anyway and whilst the dash is out there are a few other things on a minor priority list I can do whilst in there. The radio hasn't worked for the previous 18 months, yet my ears have been tuned either into the Test Channel or listening to the Supercharger Song. Edited January 7, 2013 by David P (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 7, 2013 Share Posted January 7, 2013 On a stock ECU disconnecting a knock sensor will make the ecu go onto a "safe" map and pull timing and (I think) add fuel. Nor will unscrewing a knock sensor and leaving it connected work, the ecu expects to hear some noise. Too damned clever by far. If you download Audacity or similar you can make an interface to look at the outputs of the two sensors in real time, graphically. You need to be happy building the interface though. Quote Link to comment Share on other sites More sharing options...
David P Posted January 7, 2013 Author Share Posted January 7, 2013 It's behaving like an intermittent sensor signal. Next time I'm grovelling in the foot-well, I'll check the knock sensor wires at the ECU end and if all looks good, I'll take a connector from a spare loom and try a bypass feed. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 7, 2013 Share Posted January 7, 2013 Knock sensor signals are very low level, and easily swamped by picked up noise, or iffy connectors. A really good assessment of the connections and cabling might reveal something, but as far as I know if the knock sensor triggers the ignition ramps back up slowly, so it may not give the symptoms you describe. If you go to the Motec site there's a document on their knock sensor module that may have generic info of use to you. Quote Link to comment Share on other sites More sharing options...
David P Posted January 7, 2013 Author Share Posted January 7, 2013 I've not found much information any use, I'll go and have a look. Cheers. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 7, 2013 Share Posted January 7, 2013 I may have the file here if you can't find it, it *MAY* be the help file in the software for knock control. Quote Link to comment Share on other sites More sharing options...
David P Posted January 7, 2013 Author Share Posted January 7, 2013 I didn't find the file but found the Webinars, Motec have put a lot of effort into these. I really must study the AEM User Manual. http://www.motec.com/webinars/webinararchive/ Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 7, 2013 Share Posted January 7, 2013 Damned right they have, that's what you get with Motec, great support, 24 hours a day. Here it is for you: http://www.chriswilson.tv/knock.pdf May or may not help, but don't knock it. Quote Link to comment Share on other sites More sharing options...
David P Posted January 8, 2013 Author Share Posted January 8, 2013 After watching the Motec data-logging Webinar, I've broadened my horizons and discovered that the ignition begins dicking about just before the fans cut in, not because of temperature, but because at tick-over, that's when the voltage is at it's highest. At tick-over, just as the volt-gauge creeps past 12.8, the shenanigans begin, then the fans come on drawing current and cure it, turning on a couple of things cures it too. The 200 amp alternator has already been replaced with a stock auto 100 amp unit, so the battery has become chief suspect, I'll have it tested and also curious to confirm the extended cable I used is man enough for the job. Curiouser and curiouser. Quote Link to comment Share on other sites More sharing options...
mellonman Posted January 8, 2013 Share Posted January 8, 2013 Curiouser and curiouser Im not you have aem ecu and have loads of gremlins, does the aem forum suggest firm ware anywhere with this ecu? As the firm ware seems to change how it see's signal wave lengths. Not sure if your ecu is the same but the aem fic does Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 8, 2013 Share Posted January 8, 2013 12.8 is very low, do you mean 13.8 volts? Normal alternator voltage regulator level is about 13.8 volts. Quote Link to comment Share on other sites More sharing options...
David P Posted January 8, 2013 Author Share Posted January 8, 2013 (edited) Curiouser and curiouser Im not you have aem ecu and have loads of gremlins, does the aem forum suggest firm ware anywhere with this ecu? As the firm ware seems to change how it see's signal wave lengths. Not sure if your ecu is the same but the aem fic does This is an electrical feed Gremlin. 12.8 is very low, do you mean 13.8 volts? Normal alternator voltage regulator level is about 13.8 volts. That's a conundrum too, the gauge reads 13.8v with an ignition circuit feed, or 12.8v with a constant positive from the original positive battery terminal. Edited January 8, 2013 by David P (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 8, 2013 Share Posted January 8, 2013 Multimeter set to low volts range, say 0 to 10 volts. Negative lead of meter to battery negative post. Positive lead of meter to a GOOD ground on the engine (clean bright metal) Crank engine. Watch meter, whilst cranking. More than about 1.5 V volts showing is a bad engine to chassis ground. If that's OK negative meter lead on engine block still. Positive on alternator body. Read meter after starting, preferably after leaving some stuff on to get the battery state pretty low, and make the alternator work hard upon the engine starting. More than about .5V showing, bad alternator to engine ground. Could conceivably be a totally shot battery, but I would have thought it wouldn't start the engine after leaving overnight. Quote Link to comment Share on other sites More sharing options...
David P Posted January 8, 2013 Author Share Posted January 8, 2013 Both engine and alternator have additional ground wires and the battery is as strong as it ever was, yet I've noticed a hic-cough and timing-spike sometimes, second or third attempt at cold start. I'll get it into "shenanigan" mode and then clip a jump-lead from the battery at the back to the OE positive terminal at the front and see if that shuts it up? Quote Link to comment Share on other sites More sharing options...
mellonman Posted January 9, 2013 Share Posted January 9, 2013 dave what AEM ecu are you running exactly? Quote Link to comment Share on other sites More sharing options...
Shane Posted January 9, 2013 Share Posted January 9, 2013 12.8 at the batterry is too low, you obviously have a grip on it now, but if it was me I would be measuring the the voltage at the alternator, and comparing it with the voltage at the battery. If its simply voltage drop from where you have moved your battery to the boot then it cant be much other than cable, connections or grounding I wouldnt think. I would say bring it over at the weekend but am a little busy on Saturday Quote Link to comment Share on other sites More sharing options...
David P Posted January 9, 2013 Author Share Posted January 9, 2013 dave what AEM ecu are you running exactly? Series one 30-1100. 12.8 at the batterry is too low, you obviously have a grip on it now, but if it was me I would be measuring the the voltage at the alternator, and comparing it with the voltage at the battery. If its simply voltage drop from where you have moved your battery to the boot then it cant be much other than cable, connections or grounding I wouldnt think. I would say bring it over at the weekend but am a little busy on Saturday I 'angled' to do that last weekend, yet when I discovered what you are doing next weekend thought better of it. Quote Link to comment Share on other sites More sharing options...
Shane Posted January 9, 2013 Share Posted January 9, 2013 Series one 30-1100. I 'angled' to do that last weekend, yet when I discovered what you are doing next weekend thought better of it. Oh I see, sorry! I was pretty busy when you called, not helped by screaming kids and visitors. Next time, just ask! Quote Link to comment Share on other sites More sharing options...
David P Posted January 9, 2013 Author Share Posted January 9, 2013 (edited) I heard the bedlam and let it pass, put me on the list for when your dust settles, it looks as though the fystery will still be mucking around. I had the choice to work standing in 1" of mud or 2" of water over hard-standing, the mud was in the shade so chose the sunny water, there was no wind so I emptied out the back of my Supravan onto the roof and checked the battery, all looked fine, but nipping up the earth terminal gave back the missing volt. I was hopeful, but the 'shenanigans' now behave just the same at a volt higher. The jump-lead link made no change either. When I can next get to the workshop, I'll treat myself to some cross a job off the list therapy and do a nuts&bolts job swapping the diff, it looks to be turning too cold for a soldering iron job anyway! Edited January 9, 2013 by David P (see edit history) Quote Link to comment Share on other sites More sharing options...
chrispot Posted January 11, 2013 Share Posted January 11, 2013 (edited) another thing to try is the alternator sense wire, what is does is sense the voltage at the battery and is connected to the alternator to adjust its output to keep the voltage at the battery 14.2v (alternator could be at 15v trying to keep the battery at 14.2v) what you could try is take the sense wire from the front of the car (in the fuse box with a 7.5 amp fuse) and put this on the battery which is in the back. A quick test could be done, if you remove the sense fuse and connect wire there and at the battery. another to try (but there should be no need to) is a large capacitor like the ones used in some car sound systems connected at the front to reduce any voltage spikes? another could be to place a diode inline with the sense wire this would up the charging voltage by .7v or so Just thought there could be a problem with the sense fuse, connection or wire and no need to do any of the above. good luck regards chris some older cars never had the battery sense and had to rely on voltage that the alternator was set at. so when a heavy load is used the voltage would drop and the alternator would put out a high current, but instead of 14v or so reaching the battery it may have only have been getting 13v at the battery because of the losses in the cable. Edited January 11, 2013 by chrispot added some more letters etc (see edit history) Quote Link to comment Share on other sites More sharing options...
David P Posted January 11, 2013 Author Share Posted January 11, 2013 (edited) In the workshop there are 8 cars rescued from the crusher, 4 more wrapped up under the lean-to and a couple more on the concrete pad. I had access to work on the road-stone drive this afternoon, I was reluctant to swap the diff on this surface, but beggars can't be choosers and I want to move the project along. Trolley jacked it up, chocked the drivers side front wheel and as I have done many times before, supported the body on a pair of seam-seating axle-stands. It was a dim old day, so removed the wheels to let some light in then laid on the whoopee cushion and removed the 6 prop-flange bolts. As I lay there wondering which bolt to undo next, I heard a faint crunching sound and quickly wriggled out from under. CRUNCH The bumper brushed past my left shoulder on the way down. It was a very close shave and I'm lucky to be alive. There's a foot or more of compacted hard-core and 2 inches of road-stone chippings, but the ground's not quite level and one of the axle-stands wasn't happy about it. The mat I was laying on was directly under the diff before the car fell. These shenanigans used up the day-light, so I just checked it over and put it back together, the diff will get swapped in the snow soon. Fortunately, no damage was done, yet I'm beginning to think that God doesn't want me to finish the Project. Edited January 11, 2013 by David P (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 11, 2013 Share Posted January 11, 2013 Very dangerous! Please put the two removed wheels and tyres under the car once it's on the stands as a secondary support, if anything slips they will still support the car. I mean one wheel atop the other, unless you are remarkably skinny. So that's 9 minus how many lives now? Quote Link to comment Share on other sites More sharing options...
J-Meiser Posted January 11, 2013 Share Posted January 11, 2013 Wow! That was a lucky escape! It's because of things like this why I'm always wary of working underneath cars. The main thing is that you're ok and not received any injuries Quote Link to comment Share on other sites More sharing options...
JasonR24 Posted January 11, 2013 Share Posted January 11, 2013 Dammit! Was there any damage to the car?! Quote Link to comment Share on other sites More sharing options...
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