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PWM Option when populating MS ECU board

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Hi all! 

I'm well into building the Megasquirt ECU kit which I got from Nige recently. (As I am a bit of a magpie, there was also a lot of other shiny stuff in the box which I am itching to play with.) Ultimately, everything will come together with a 4.6 Thor engine which is going to be transplanted into a 2001 Defender. 

I've been using these instructions: http://www.megamanual.com/ms2/V3assemble.htm and I reckon I have picked the correct options on the way down and the tests have worked at each key stage. 

I am confused about the output options. I have the "Thor PWM Control Kit" from Nige to fit. 

My questions are: 

1) Do I follow the modification for "For PWM Idle Valve Users Only"  (Around step 62; it says "Do not install Q20, do not install D8, and jumper R39 as well." The step also involves not installing Q4 and using a more powerful TIP120/121/122 transistor. I realise this sounds like a stupid question, but Nige's site says of the PWM kit ''This will immediately work with our standard ECUs current or past, without any additional electronics or programming required.' So, I am wondering if either the standard transistor setup can handle this particular PWM device or all of the pre-built ECUs are going out with this mod. 

2) At step 69, I can choose to install the 'PWM flyback damping circuit'. Should I install this or not? 

I am quite happy to be told that I have missed something, but I always think that the stupid questions are the ones we don't ask. So..... can anyone help? 

kind regards

 

 

Ian

 

 

 

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If you're aiming to hit the same setup as Nige's stuff then this is what you're aiming for:

 

v3_edis_minimods.jpg

 

v3components_minimal.png

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Wow! Thanks very much for the comprehensive reply. I bought the Thor kit from Nige along with his suggested mods and upgrades, so I am very much looking to do it 'his' way. I will study the pictures and follow these mods where they differ from the ones suggest on the v3 build page. 

Thankfully, I haven't done too much of the output stage yet, so this is very timely advice. 

Thanks once again, Mr FF. 

regards

 

Ian

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HIS way ?... :rofl:

 

I have a proper grown up do ECUs,

 

The thought of me doing those electricitky bits and waving a soldering iron would be similar to Mongo from Blazzling Saddles doing a Pacemaker fiment :D

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Ok. :D

I'll keep my electron manipulation questions for the collective. Am I right in thinking that when you get involved, the magic smoke escapes from the components and they stop working? 

I have other questions about transplanting which might suit you better. I'll post them in the other section. 

A quick question for Mr FF, if I may: I notice that on the schematic, Q9 and Q12 are white which is keyed 'do not fit'. But, they are populated in the photographs. Looks like they might relate to my active flyback circuit question. I would appreciate any thoughts, but especially the decision process. 

I am sure that the content of this thread might be useful for those non-Nige types who like poking things with a hot iron. :ph34r:

 

regards

 

 

Ian

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The diagram is newer than the photos - the evolution is towards not fitting stuff you don't need as it means less to go wrong.

For example, Q2+Q19 form a current limiting circuit for the fuel pump relay, but that means a lot of the time that circuit causes Q2 + Q19 to dissipate a lot of heat as it operates near the threshold for a normal relay... which means Q2 + Q19 are more likely to fail. Deleting the current limit circuit means Q2 is on "hard" all the time and not overheating, making it MORE reliable The trade-off is that your fuel pump relay circuit is longer idiot-proof, so if you short-circuit 12v into the pin you'll blow Q2 up, but that's your fault.

Same deal with the PWM flyback, if you're not driving Low-Z injectors using PWM (which you shouldn't be) then having the protection circuit fitted is a similar extra thing that *could* fail in the wrong circumstances.

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Ok. Makes a lot of sense. I will follow the diagram. I am making an assumption that the standard LR injectors are Hi-Z otherwise I am sure that Nige would have warned me. :unsure:

 

 

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Only the flapper were low-Z and they had a resistor pack to bring them up to Hi-Z.

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Ok. I finally had some time today, so I have finished building the board up to exactly match the diagram. Plugging into the Jimstim (V1.5 board and v2.04 software), the gauges respond as I would expect, but I don't have a reading for Engine Speed/RPM. 

I'm starting to dig around for some documentation on the JimStim to see if I need to set/change any jumpers or switches to provide a suitable signal for this MS configuration. Any advice is, as always, very welcome. 

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Ok - it turns out that I am a little bit myopic! I had linked XG1 to XG2 as per the megabuild manual and missed that FF's diagram did not have this jumper in place. I cut the link, powered back up and she breathes! 

So, lights are flashing everywhere, gauges are moving around and I'm a happy chappy. Now to carry on stripping the V8 out of the Discovery! 

 

 

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Result, well done!

I'll admit my wiring scheme is odd compared to the manual but it minimises the number and length of jumper wires required and keeps things as neat as possible.

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Thanks! Now I have read your diagram in conjunction with the relevant bits of the manual and taken into account your comments about simplification earlier in this thread, it makes a lot of sense. 

I had to pick up a 1.3K resistor which cost me all of 10p. I'm just going to make up the bit of vacuum pipe with the brass connector and I will close the lid (at least for a little while). :D

I notice that the lamda reading on Tunerstudio gauge goes down as I turn turn the O2 pot on the stim clockwise. Is this normal behaviour?

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Yes, Lambda sensor is reading the exhaust gas O2 (oxygen) content, also known as EGO / EGO2... there's too many acronyms!

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