driversdomainuk 8 Posted July 13, 2007 Hi I know this sounds rather dim, but I know bugger all about electrics/ignition The engine I am picking up tomorrow (circa 200bhp Mi running twin 45s with delimited ECU) has well....a delimited ECU! However, now for the dumb bit....my 8v has twin 45's but no ECU.... how does this work then..? why does this MI engine still have the ECU and why has mine gone..???? PS - what will an MI rev to..? bearing in mind I have forged pistons and conrods? Cheers Share this post Link to post Share on other sites
driversdomainuk 8 Posted July 13, 2007 (edited) Sorry, I know the ECU must be located under the sterring wheel off to the right.... I am meaning will my ecu still be working/or what parts of the ecu will still be active as my 8v engine, which is soon to go runs carbs and so no AFM, SAD etc....? Edited July 13, 2007 by driversdomainuk Share this post Link to post Share on other sites
danpug 1 Posted July 13, 2007 It sounds like when that car was originally mi converted they kept the 8v management and used a de-limited ecu, it isn't any use now its got carbs though! Share this post Link to post Share on other sites
Ryan 99 Posted July 13, 2007 Perhaps it had a delimited ECU before the carbs were fitted, then the seller got someone else to fit the carbs and doesn't know the ECU is now redundant? Share this post Link to post Share on other sites
driversdomainuk 8 Posted July 13, 2007 Perhaps it had a delimited ECU before the carbs were fitted, then the seller got someone else to fit the carbs and doesn't know the ECU is now redundant? Thats ok then - thought I was going mad, either that or I know fcuk all about engines LOL!!! So how does aftermarket ecus work..? you must have TBs for this and not carbs? Share this post Link to post Share on other sites
brumster 135 1 Cars Posted July 13, 2007 So how does aftermarket ecus work..? you must have TBs for this and not carbs? Not strictly speaking, no, you can get engine management that just maps the ignition for you (obviously no injection because you're on carbs). More tuneable than just running a dizzy-based solution but ideally you'd get a 3D mapping system that does injection too, and run TB's, for the 'ultimate' setup. Share this post Link to post Share on other sites
driversdomainuk 8 Posted July 13, 2007 Not strictly speaking, no, you can get engine management that just maps the ignition for you (obviously no injection because you're on carbs). More tuneable than just running a dizzy-based solution but ideally you'd get a 3D mapping system that does injection too, and run TB's, for the 'ultimate' setup. But basically a "delimited ecu" will be totally useless with a carb'd car? Share this post Link to post Share on other sites
brumster 135 1 Cars Posted July 13, 2007 (edited) But basically a "delimited ecu" will be totally useless with a carb'd car? Sorry, wasn't making comment on the delimited nature. I presume that just means it's had it's rev limiter removed? [shudders] Not necessarily. If the ECU is controlling the ignition, then it's not useless, and could have still imposed a rev limit by retarding/cutting the spark, even if it had no control over the fuelling. EDIT: Sorry, this is a STANDARD Motronic/Jetronic ECU, not an aftermarket one, you're getting right? I don't like removed rev limiters, ever since a throttle cable snapped on me mid-stage and sent the revs through the roof at the stage end before I got chance to cut the ignition . Cost me some sheared flywheel bolts but could have cost me a lot more, including bent valves or a trip into a ditch if I'd not been paying attention! Edited July 13, 2007 by brumster Share this post Link to post Share on other sites
driversdomainuk 8 Posted July 13, 2007 Sorry, wasn't making comment on the delimited nature. I presume that just means it's had it's rev limiter removed? [shudders] Not necessarily. If the ECU is controlling the ignition, then it's not useless, and could have still imposed a rev limit by retarding/cutting the spark, even if it had no control over the fuelling. EDIT: Sorry, this is a STANDARD Motronic/Jetronic ECU, not an aftermarket one, you're getting right? I don't like removed rev limiters, ever since a throttle cable snapped on me mid-stage and sent the revs through the roof at the stage end before I got chance to cut the ignition . Cost me some sheared flywheel bolts but could have cost me a lot more, including bent valves or a trip into a ditch if I'd not been paying attention! It will be a standard ECU I am getting...So will I be able to bin it as I dont currently run an ECU and the Mi engine has been converted to take 8v dizzy and loom. Will probably buy a rev limiter and set it to 8,500rpm.... Share this post Link to post Share on other sites
Hilgie 16 2 Cars Posted July 17, 2007 If the Mi has been converted to take 8V dizzy and loom then you can bin the ECU. If the Mi is still running its stock ECU (Motronic) then you should retain the ECU for ignition only. Share this post Link to post Share on other sites
petert 580 Posted July 17, 2007 If the Mi is still running its stock ECU (Motronic) then you should retain the ECU for ignition only. You can, but how does the ECU sense the engine load to determine light ignition advance for cruising? The AFM normally supplies this information. So expect to get poor fuel economy and less than fantastic part throttle response. Share this post Link to post Share on other sites
Hilgie 16 2 Cars Posted July 17, 2007 Yes...agreed. Throttleresponse is not a problem though but fuel economy is out of the window then. Share this post Link to post Share on other sites
