Quote from: dieselgeek on June 24, 2014, 04:47:47 PM

but my money is on the megasquirt recording the falling edges accurately. 

-Scott

Would that be a trigger positioning thing, or a trigger type problem.

I'd believe a possible triggering issue (sensors, targets, or circuit conditioning on the Megasquirt inputs we are using) causing error...  but I am confident in the processor and code accurately recording the position of the falling edge signals it's seeing.  Otherwise we'd have to question the ignition timing, and anything else referencing crankshaft position.

Quote from: dieselgeek on September 08, 2012, 10:45:09 PM

What a bummer.

If you're free I'm coming up there to figure out what's going on with your starting issues in the Shelby.  I've never seen TWO bad EMS-pros but it's possible I guess?  (Jay has a spare that also won't work).  Meanwhile, both EMS's did work when the engine was last dyno'd, yes?  I am wondering if there's a flaw in the EMS-pro wiring harness in the car.  The EMS just isn't getting the same signal seen down at the sensor with an oscilloscope...

Scott, I am free and would love to have you come up for the weekend to help figure out what is going on.  I would be the first one to point a finger at the wiring harness in the car, except that it hasn't changed from last year, and the car went down the track twice and also went down the road with this harness.  Is it possible that there is a flaw in the wiring harness that could affect only the starting?  Maybe its noisy, and that makes the car harder to start?

At the time I ran the engine on the dyno (last summer), I only had the one ems-pro.  It did give me some issues, but on the dyno I was able to crank up the battery voltage by turning the battery charger on boost.  This spun the engine faster and it seemed to start better like that; maybe it was just higher battery voltage?  FYI after our calls yesterday I did check the voltage on the Tuner Studio dashboard during cranking, and it was about 11.5 volts with the starter spinning.  That should be plenty of voltage based on our previous conversations.

Color me pretty confused on this one...

Check my email, my schedule this weekend just blew up thanks to the EMC / early Hemi guys deciding to.

But, I did do some testing late last night with an EDIS wheel and two different sensors on an EMS-pro I have here at home.  I was able to log cranking RPM down to 35-40RPM with both a Hamlin and Cherry sensor (hall sensors, Cherry required a pullup), and using a Ford VR sensor I was able to get it down around 65rpm steady cranking, with the EMS-pro identifying cranking RPM without switching to Run mode.  I use a variable speed Ryobi drill press to control RPM.   This EMS has your specific modifications to the tach inputs, but it's got a dead injector driver (it was a warranty swap for a guy who miswired his fuel injectors).  I don't think the dead driver portion of the board improves or hurts the tach input performance.

We've done similar testing with Huber and Bill Fowler in the past all with good results.   There is something in your combo that I am missing / haven't figured out.  But I will!  There are way too many people using the exact same combination not having the same problem for it to be something other than software config or hardware.  I can send you some of those guys' tunes if you want to load them and try them out?  just to see if you get cranking RPMs.

-Scott

A heads up on the TPS function in the MS3X, it's only used for accel pump shot.  It doesn't control the fuel in the defaul tune that I set up.


IMO, the problem is most likely going to be air distribution at idle.  With 8 O2s or EGTs you'd likely see as you get lower in RPM, the EGT/O2s will vary wildly cylinder to cylinder.  The "shut off" point is the point where more cylinders are misfiring, than those firing.


I think working with the plates as CDMBill suggests is likely the best approach.   I'm not sure why you're having an issue with the datalogging, it's very rare, but we can always get on the ms-extra web forums and ask about the problem you are seeing...  meanwhile, keep an eye on the Ignition Advance gauge and the Pulsewidth gauge.  If either of them do something strange when the engine shuts down, then there would be a problem with the tune.  There might be a better combination of fuel and ignition timing than what's in there now, to run below 1400rpm, so it might be that as well.

Meanwhile, once the engine is in the car, the idle tuning will be largely different than that on the dyno, as the dyno loads the engine at low RPMs somewhere around 20-50hp, versus in the car with no load other than the accessory drive.  You might have a much easier time tuning idle in the car then on the dyno.

expecting 850, hoping for 900.   Sounds like a good goal!!  See you on Saturday morning,
-Scott

Jay, the Jag engine for my land speed car is distributor-less and makes use of a coil-on-plug layout. The problem is that the individual coils are about the same size as your thumb and are prone to failure. I'd therefore decided to make use of the same sort of arrangement you are using. What is the source of the coils you are showing in the pictures above? Thanx!!!

KS

Hi KS,

The IGN1-A coils Jay uses have onboard transistors (also called ignitors), where your OEM-style coils might not.  There are versions of this same coil without the transistors, make sure to ID which type you need before purchasing,

-Scott

Cool!!  That will probably work better than you hope.  What are you using to control them?

Jay, check out the spreadsheet I sent you.  A friend made this a few years back, to help un-confuse the trigger wheel setup.   It'll either help dramatically - or confuse further - let me know.  Fighting valvetrain probs in CA this morning, so I have a little downtime.