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434josh

Link Extreme replacing Megasquirt

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Well I did it, the MS3Pro is long gone now and I am currently wiring in my new Extreme. On to the Link NOOB question of the day.

 

There are some distinct terminology differences on the A&B plug wiring schematics vs the Megasquirt so please bear with me. 

I am running a 36-1 crank wheel with a hall sensor and a camshaft synchronizer with a single tooth VR pickup. The Megasquirt had a dedicated CPK+, CPK-, CMP+. CMP- however on the Link I am only seeing Trigger 1 and Trigger 2. I am assuming the CPK+ and CMP+ would go directly to the trigger inputs and based on the help file both the shield and the two -'s would go to sensor ground --- but there isn't anything labeled sensor ground. Only ground, ground out and shield/ground. Am i right to assume the Shield/Ground is in fact the sensor ground? If so, there is one listed for each plug, so are they totally independent of each other or linked together on the board? What exactly is the ground out and its purpose?

Then my last question for the evening is the trigger offset. My missing tooth is 81.5* BTDC which is what the Megasquirt liked and gave the theoretical best rpm range. Will that work with the Link ecu? Should i simply replicate that trigger offset in the set base timing page?

Thanks for all of your help. 

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Trigger 1 is the primary sensor (usually crank), Trigger 2 is the sync sensor (cam), so yes these are your CPK+ & CMP+.  The pins labelled "Gnd out" and "Sheild/Gnd", are both sensor grounds and can be used interchangeably.  Typically for triggers we splice the sheilds and the two trigger grounds together and connect them all to the shield/gnd pin that is right next to the trigger pins.

As for the trigger offset question, the "reference tooth" that the offset is measured from is the tooth that comes immediately after the gap.  So if the centre of your gap is 81.5BTDC then the reference tooth is probably about 71.5BTDC.  This would translate to a trigger offset of -71.5 in Link language.  Or possibly 360deg later (288.5) depending when your cam tooth passes the sensor.   

Im not sure what limitations the MS had in terms of gap position but with Link there is no limitation, you can have it wherever you like.  However it is generally best to have the gap outside of the area your spark normally occurs (say 0-40BTDC) as when there is no tooth there the ECU has slightly less info to predict engine position as accurately.

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Ok Adam, I have another set of questions maybe you can help with...or anyone else. 

The link is all wired in. Injector tests all look good. Dbw e-throttle is setup and calibrated, working great. Getting an RPM signal while cranking (36-1 crank/hall with single tooth vr cam sync) but not getting any coil fire. Setup a coil test and nothing. Coils all have power to them. 

Not sure if they are configured correctly or not. Megasquirt needed the coils set for "going high" and stated that 99% of setups will use going high. Link states most setups will use "Falling". That first through me for a loop because at a glance it would seem going high would = rising but reading the description I am understanding falling means it charges when a rising signal is given and triggers on a falling signal. Is that correct? My coils are GM LS D514 coils. Would Falling be the correct setting?

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Correct, falling is the correct setting for those coils.  The MS terminology "going high" is a bit ambiguous and I suspect probably a leftover from old days when their DIY boxes had coil drivers built in.  Pretty much all other ecu's nowadays use the same convention as we do which is "falling edge" means the coils spark on a falling edge (i.e. when the coil input pin is grounded).

So, Im not sure if that helps your situation.  There are a couple of different pinouts for the LS coils, I think yours should be the "LS2" wiring right?

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These coils were on the motor before and wiring didn't change. Same switched power, chassis ground, ecu ground, same trigger signal from the ecu.  

Screenshot_20180628-062337.png

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I guess the next step then is to get a LED test light or noid light etc connected to the ignition wire and see if it flashes with the ignition test on.  Also make sure that Pin B does have continuity to ground.

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Coils are firing now in test mode. Would have before but I was doing it wrong. I am occasionally getting an odd spark here and there while cranking but not consistent. 

Do you have a vid or good write-up on setting trigger offset? I am quite confused on this process. With the Megasquirt I simply entered 82.5 which was the number of degrees btdc where the missing tooth fell and it fired up. Adjusted it to 80.5 to get it spot on. If I enter -80 in the adjustment page and hit ok the number resets to zero so I am not sure if that made a behind the scenes adjustment or if it did nothing. 

I am thinking it maybe doesn't like where my missing tooth is in relation to my cam sync combined with generally being off in terms of the offset. But that's just a guess. 

I know it's reading my crank sensor as it's registering rpm while cranking. However doing a trigger scope is barely registering anything.

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4 minutes ago, 434josh said:

If I enter -80 in the adjustment page and hit ok the number resets to zero so I am not sure if that made a behind the scenes adjustment or if it did nothing. 

You have to hit enter after typing in a new offset, it should turn blue to indicate it has been applied.  This catches out lots of users as for some reason this field behaves a bit different to most others in PC Link where you dont have to hit enter to make the change.  A reference tooth at 80BTDC should convert to a trigger offset of -80 (or 280) depending on cam tooth position so you have guessed that right.

 

Also, can you do us a triggerscope while cranking so we can see if there is anything to worry about there.  Here is a quick video showing how to do that:  https://1drv.ms/v/s!AiYbYlZQuRHPmieMTkwQDCXEb2LY

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I did a few trigger scopes. One showed a good waveform for the crank but the single tooth cam sync was showing several trigger events per revolution. I will correct the trigger offset tomorrow and try again to see if that helps. 

Thanks. 

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Update...

I get good spark with wasted spark but nothing in full sequential so it's something with my cam sync. 

It runs and I got the fuel table setup enough to idle and rev for about 20 mins. Let the fan cycle a few times and all seems good. I am liking the e-throttle control. 

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Please do a triggerscope as per the video above, we can then see what it is not happy about.  Its quite possibly something simple like the arming threshold on trigger 2.

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Well I did several trigger scope logs and they all showed data on the screen but opening them up later they have no data.

 

 

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48 minutes ago, 434josh said:

Well I did several trigger scope logs and they all showed data on the screen but opening them up later they have no data.

 

 

does the file size say "0Kb"? 

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11 hours ago, Adamw said:

does the file size say "0Kb"? 

No. They were like 27 and 35kb but when I open them in the log viewer everything says no data.

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11 hours ago, 434josh said:

No. They were like 27 and 35kb but when I open them in the log viewer everything says no data.

Then it sounds like they are ok.  In a triggerscope log the only parameters that will have any data are called "trigger scope 1" and "trigger scope 2".

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Your cam sensor polarity is reversed, swap wires around.  Its also got a bit of a nasty secondary "bump" just after the tooth, we can probably mask that using the arming threshold.  Swap the wires and do another triggerscope during cranking and attach that here.  After seeing that we'll decide if we can make it work.

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