AdmiralSenn (Adam S.) #3416 "Christine" Megasquirt conversion

As I approach finally getting 3416 rolling again, I'll be documenting things here, particularly my settings and some of the things I've done differently and most especially as they pertain to converting using an original manifold. Hopefully this will be a lot more coherent than my prior attempts.

For startings, I'm using a dual fuel rail system (each rail on its own ports on the fuel regulator), 29.5 lb/hr high impedance injectors on two alternating banks, on a 3.0L odd-fire block with custom headers, lightened flyhweel, MSD coil and wires with plugs gapped to .05". I will also be setting up Megasquirt to control ignition next year, and once that's dialed in I'll be controlling a nitrous oxide injection system through MS's auxiliary outputs.

Cool. The ignition is a lot easier than fuel. The hard part is actually biting the bullet and putting that tack weld on the centrifugal advance inside the distributor! I think there is a lot of optimization that can be done with the advance table. Mine is set to pretty much mimic the actions of the vacuum and mechanical advances of the stock engine with the exception that I get the advance in quicker. So far no knocking, so I think I'm ok. I may experiment with a knock sensor to "push the envelope", but not yet.

Next step is to get position sensors (hall) on both cam and crank so that MS can control the spark for each cylinder (via coil on plug or coil pack) and get rid of the distributor all together. Now THAT would be sick. Being oddfire we don't have the option of going wasted spark. Since our ignition events are not equally spaced, the MS unit needs sufficient information to know when we are TDC on #1 to get the timing right.

Yeah, full COP would be awesome.

Unfortunately I still have to track down the culprit behind my RPM issue. Not sure if it's my RPM source or the board or what, but TunerStudio insists that I'm running at either 1500 rpm or 0 pretty much constantly. It seems to work great once I get it revved up above that point though. I'm going to investigate the VR input trim pots first.

Stupid question: Wouldn't switching to coil negative input (grey/slate wire) interfere with ignition control later? I can't wrap my head around the idea of MS both controlling that coil trigger and reading RPM off of it. I'm only asking because I wonder if the problem isn't my tap into the VR sensor.

I'm going to try to get in the garage and fiddle with the computer to see if I can shut down the RPM problem. Once I get my rear fascia back I can start tuning in earnest, as long as I have daylight and empty roads handy. I'd rather not be stuck waiting while I tackle this new issue.

I can post ballpark req_fuel and idle pulsewidths as soon as this problem is fixed.

The pulse trigger and the coil pulses should have the same timings. So technically the MS should be using that signal for RPM. But you should use the white/slate wire to read RPM and not the + side of the coil. You can read the RPM of either but the - side would have more voltage swing.

Adam, Bitsyncmaster (Dave) was really helpful when I was having issues getting my spark control up and running. We need to get him into this camp and developing the next evolution of ignition control or other cool things for us!
:relative:

I need to do a little remembering of how/why mine is setup the way it is, but my immediate recollection is that I go from VR straight into MS. No slate/white wire. Let me go back and check on things before you take that as gospel.

*sigh*

I suspect that either somebody is slipping something into my food, or someone is screwing with my car in between work sessions.

I went and checked out the car again today. First thing I found, the VR pots were turned about six turns clockwise - I always ran them fully disengaged counterclockwise and then MAYBE half a turn in. Fixed that and it made a marked improvement - TunerStudio now reports accurate RPMs and the car starts far more easily. So I guess I don't have to modify my input circuit after all, which is good.

Second thing I noticed, my tune was based on MS2Extra 2.1.0.... which came out before I even got the laptop that I use for tuning. How I managed to download a version of the software that's two years out of date is beyond me. Now running 3.1.1 and it's running great.

Currently running at ~1.3-1.5 pulsewidth at idle. If it wasn't hunting and seeking I could get it to idle at ~500 RPM no sweat, maybe lower - it will randomly decide to oscillate up and down and at that low of a speed it takes it too slow to keep running. Req_fuel 10.8 at the moment and AFRs in the 13-15 range - again depending on oscillations. Prior to the code update the same settings were yielding something more like a 9 or 8 AFR.

My garage light just went out again so I'm done for the night. I definitely have an exhaust leak so maybe Thursday I'll pop off the header and muffler and see if I can bend them back into shape - the muffler end is slightly ovaled out so the car sounds vaguely lawnmower esque.

I do think that the car is overall still running a bit rich and/or needs yet another set of spark plugs. I was running it at ~19 degrees advance (whatever the maximum is with no advance) and after the update I can get it to run decently at ~13-15 but it's SO MUCH HAPPIER at the higher end that I don't like to leave it that way.

What are you guys running for your idle advance?

And yes, the more of Dave's brain that we have access to, the better. Having a wizard is never a bad thing.

It sounds like you should be rejoicing not sighing! Your injectors are so large (29.5 versus my 19 pound/hr) that I wonder if you aren't doing yourself a disservice with the terribly small pulsewidth. Bigger isn't always better; it's how you use them.
:devil:
We'll keep working on Dave (Bitsyncmaster) and get him over to this (unstated whether the light or dark side) of the force. He would truly appreciate the hardware and software flexibility of Megasquirt and I could see him having a field day with it.

I'd forgotten that you were advance controlling as well. Yes, those VR pots are important! Check my advance tables in my project thread. I'm fairly happy with it, but God only knows if it could be optimized. I followed the philosophy of the stock design, vacuum advance going up and then decaying, mechanical advance continuously increasing to a maximum of 37 total degrees. I try to get it all in by 2000 rpm if I recall.

Quote:

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Originally Posted by AdmiralSenn

For startings, I'm using a dual fuel rail system (each rail on its own ports on the fuel regulator), 29.5 lb/hr high impedance injectors on two alternating banks, on a 3.0L odd-fire block with custom headers, lightened flyhweel, MSD coil and wires with plugs gapped to .05". I will also be setting up Megasquirt to control ignition next year, and once that's dialed in I'll be controlling a nitrous oxide injection system through MS's auxiliary outputs.

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Are you using the engine from the 3.0L PRV?

I have one of these sitting around, and am very interested in doing the swap.

Perhaps we can bring back the "3.0 swap and support" thread?

--buddy

I have 24 lb/hr high impedance injectors. At idle, I have pulsewidths around 3.5-4, an AFR around 14 once warmed up, and MAP at ~35.

Mike et al: I'm not sure where the ~1.5 pulse width in my previous post came from... looking at one of my logs it is CLEARLY idling quite happily at ~3.3-3.5 (lowest at 2.7), MAP at ~36, lowest at 33, six squirts alternating. I'm not sure what happened with my brain there. I could just be tired. The old tune ran in the 1.5 range and it never did very well, maybe my memory got mixed up. Shouldn't happen at age 24, but... I guess it's a good thing the lights went out when they did.

Owen, I'm not yet doing ignition control, just fiddling with the mechanical dizzy still. I'll be doing that map after fuel makes some kind of sense. Either way the advance numbers should be somewhat similar. And I know these injectors are huge, but I'm planning to use them on the nitrous oxide re-installation and then later on my supercharged build if/when I can afford that project. They're on the upper end of sanity for sure but they WILL let me drive it adequately.

nullset (buddy?), it's actually a very bizarre motor... PO did a lot of work to squeeze 3.0L pistons and rods into a factory odd-fire bottom end. I think this is the only one like it; if it ever blows up I'm just going to drop in a later 3.0 and be done with it. I don't know much about it because I didn't build the motor. I do think the 3.0L thread should make a comeback although I won't be any help with it, unfortunately.

I thought my hunting issue might be the fuel overrun settings but that's actually turned off in this tune, so I'm just going to have to keep hammering at it. I'll take a log of it if I can't figure it out and post it (tuning laptop's battery just died). The log I have shows very clear sine wave patterns of RPM, MAP, PW and AFR taking huge swings simultaneously. I'm not running any sort of idle air controller yet either so that's definitely not the issue.