JanspeedZ Posted July 14, 2011 Share Posted July 14, 2011 So in the search for more power but without lose drive-ability i am interested in megasquirt possibility First here is my base project! The car have only 92000 kms THe engine is F54 with N42 head, no EGR or AC the only modifications was JR direct filter, cranes cams coil, and taylors wires , sport muffler and double output Here is the result: Good just below the origin, normal for the kms... and here is also the lambda result, normal tune for economy... Quote Link to comment Share on other sites More sharing options...
JanspeedZ Posted July 14, 2011 Author Share Posted July 14, 2011 Talking with the mechanics at the dyno shop about megasquirt, he tell me that he don't like this system, he had experienced it several times but he say that the megasquirt computer was not accurate about the RPM information He had see several time 300 rpm variation in the rpm information! Someone had ever hear the same thing? about megasquirt? Quote Link to comment Share on other sites More sharing options...
Cannonball89 Posted July 14, 2011 Share Posted July 14, 2011 Most dyno shops will clamp their tach signal onto one of the spark plug wires just like a timing light, this is not an accurate way of measuring the RPM at all due to the noise coming off of the other plug wires. I can see where their would be a discrepancy in the RPM data at high RPM but it is almost certainly an issue with the shops RPM data, not megasquirt. If megasquirt is not reciecving accurate RPM data then the computer will lose sync and the engine will stumble and miss until it syncs again. I can't believe a shop would tell you that. Megasquirt has been proven to be rock solid and reliable on hundreds if not thousands of Z cars and is going to be the cheapest aftermarket efi system for your car with loads of support available to you. I would not use a shop that believes their RPM data to be more reliable than the ECU. Quote Link to comment Share on other sites More sharing options...
JanspeedZ Posted July 14, 2011 Author Share Posted July 14, 2011 The rpm for the dyno was take on the battery! not on the plug wire The guy say that he works with several made, but same are not so accurate than the other because of there internal components! Is critical about megasquirt is that when he works to find the better data chart for the fuel times or ignition the rpm values moves and jump, for him the reason is the system that not convert correctly or not enough speedy the rpm signal deliver by the rpm sensor... Quote Link to comment Share on other sites More sharing options...
JanspeedZ Posted July 14, 2011 Author Share Posted July 14, 2011 My project with megasquirt is to change the calculator but keep all the original sensor and actuator except the AFM and the TPS (upgrade to a better one, or a 240SX body...) First i will be very happy if i could do that and have a good benefice AFter if all is ok, i will convert to an upgrade Ignition piloted by the megasquirt calculator Quote Link to comment Share on other sites More sharing options...
Cannonball89 Posted July 15, 2011 Share Posted July 15, 2011 How can the battery possibly tell you anything about RPM? Correct me if im wrong, but I can't think of anyway you could possibly deduce anything about engine speed from the battery unless your some how measuring the clock rate of a certain draw such as coil(s) firing. Quote Link to comment Share on other sites More sharing options...
JanspeedZ Posted July 15, 2011 Author Share Posted July 15, 2011 No no; is it possible, powerdyn use this method ! In reality the rpm are in the current deliver by the alternator and with the electronics you could extract with accuracy the engine rpm... http://www.powerdyn.fr/English/Powerdyn_me.html Quote Link to comment Share on other sites More sharing options...
Cannonball89 Posted July 15, 2011 Share Posted July 15, 2011 Well in that case any slippage of the belt on the alternator pulley could account for RPM discrepency. My main point is that regardless of what this shop told you, megasquirt is an accurate and reliable efi system. And your plan of using the stock sensors with megasquirt is a solid plan for now. Quote Link to comment Share on other sites More sharing options...
didier Posted July 16, 2011 Share Posted July 16, 2011 No no; is it possible, powerdyn use this method ! In reality the rpm are in the current deliver by the alternator and with the electronics you could extract with accuracy the engine rpm... http://www.powerdyn.fr/English/Powerdyn_me.html Where did you see that ? powerdyn need a DIY inductive coil around one HT spark plug wire, and records the data with a wave file or other one I think nothing is better than a trigger wheel on the crank shaft for accuracy, with a VR or Hall effect sensor A perfect square wave signal with no noise ,megasquirt will read rpm without any problem, much better that an old inertial dyno. If you want tune your engine, you'll have to find a steady state dyno. (Not so much in France ) Quote Link to comment Share on other sites More sharing options...
JanspeedZ Posted July 16, 2011 Author Share Posted July 16, 2011 I am agree with you.... (Powerdyn have 3 models: Powerdyn, powerdyn OBD which use the OBD plug of the car to read rpm, and motor power analyzer who could be link to battery or cigar lighter) Megasquirt is not interesting for a shop because too open for every one...this is the right reason perhaps Yes if i would to convert it would be economical and open to progress after for a total update Could we use the original relay of the car ? or must we use the powerdyn relay board? Yes Change the dumper pulley and ad a trigger wheel is the more accuracy method as the distributor could jump and vary because of the driver shaft Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted July 21, 2011 Share Posted July 21, 2011 (edited) No no; is it possible, powerdyn use this method ! In reality the rpm are in the current deliver by the alternator and with the electronics you could extract with accuracy the engine rpm... http://www.powerdyn.fr/English/Powerdyn_me.html Measuring RPM off alternator speed is open to pulley slippage or just plain errors in measuring the drive ratio. MegaSquirt counts pulses directly from the distributor or crank trigger and compares them to a precision crystal oscillator. You can check out the crystal's data sheet if you like - the frequency accuracy is under 30 parts per million. Unless the MS is misconfigured (such as telling it the wrong number of cylinders), if someone tells me the MegaSquirt's RPM reading does not match their tach, my advice is to troubleshoot the tach. Usually, I've seen two common reasons for a shop to dislike MS. One is that there's not as big a margin on reselling them. Two is that they may have had to straighten out a couple poorly done installs and it left a bad taste in their mouth. Edited July 21, 2011 by Matt Cramer Quote Link to comment Share on other sites More sharing options...
didier Posted July 21, 2011 Share Posted July 21, 2011 Hi , Matt I bought your book last month( incredible sum of good informations ) and a MS2 last year ( assembled but not yet in the car, at DIY AUTOTUNE ), and i agree with you: some people want plug and play ECUs without searching inside their brain . I don't trust " professional people " speaking about products they don't know anything . regards from France Didier Quote Link to comment Share on other sites More sharing options...
jaredroot Posted August 5, 2011 Share Posted August 5, 2011 Thia thread kind of threw me off. I want a megasquirt EMS for my practically stock 1980 280zx but I am not sure what all I need to get. Is there a thread specific for that or could someone help? Thanks -Jared Quote Link to comment Share on other sites More sharing options...
akeboshi Posted September 1, 2011 Share Posted September 1, 2011 @ jaredroot I think it was worth it to megasquirt a stock l28 engine. Mine was on th fritz and I did an ms 2 conversion. It's fantastic. Really all you need is a ms2 unit, air temp sensor and a tps from a 240sx, lock out your dizzy and wire up to stock harness unless you don't wanna use harness then get the diyautotune harness. A wideband o2 is mandatory as well. I did my kit complete with wiring harness for about 700$. Considering the cheapest aftermarket ems is around 900 for JUST the ecu I find megasquirt to be a steal. It should be illegal because of how awesome it is! If you have any questions just ask. Ms forums are very supportive. Marcus Quote Link to comment Share on other sites More sharing options...
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