idling now, but some trouble with next pulse tolerance

[JustinL]

I've been making some progress recently on the car with some valuable forum help. The car will now start and idle now smoothly for a bit, but then is coughs and stalls. It's firing on all 4 cylinders, but the problem that I'm having is that the trigger +/- is nearly a constant countdown telling me it's missing teeth from the VR sensor at RPMs above 500 or so. I'm running a Dual Spark with Dual VR sensors, one from a stud on the flywheel and the other reading the 130 tooth ring gear with no missing teeth. The parameters that I found allowed me to get it running were the "next pulse tolerance". Anything below 50% would give me periodic RPMs that dropped to zero. At 60% it seems happier.

Here's my latest .msq and the log I just did of a startup and idle followed by a stall.

Very appreciative of the help,

Justin

[JustinL]

Ok, After some further research I know I need to make a couple of changes. I think I need to switch my inputs to falling edge. I can't find much documentation for the m-0 with crank sync so I've been using mostly the missing tooth documentation. I'm struggling with what to set my delay teeth at. I currently have it at 0, but I'm now thinking it should be 21. The crank sync is on VR2 at 58.6° BTDC so I would imagine 58.6/360 x 130 teeth = 21.16 is the correct math.

Justin

[grippo]

The easiest thing to try is changing the input to falling edge. Input 1 polarity is changed on the regular ignition menu and input 2 is changed through the dual spark option on the Advanced menu. I would try changing input 1 first because that is what is causing the missing counter to count down.

The documentation for timing for N-0 is the same as for N-m, just assume there is a missing tooth where the stud input comes in. Before changing trigger offset I would measure the timing with a light to see if it is anywhere near where it should be.

[JustinL]

I tried switching it to falling edge(inputs 1 and 2), and the same symptoms persist. I can watch the trigger add/sub gauge count down to a reset. What exactly does this count? Is this the input from the crank sync, or the toothed wheel? I can swap my motronic ecu back in and it runs fine, so I think the sensors are working. Another thing I noticed is that I don't get any tach movement in the instrument cluster from my tach-out microsquirt wire. I'm not sure if it's related or not, but I'll tackle that after it gets running.

I attached another log, but it's very similar to the previous.

EDIT-- I think I found a wiring problem... will solve that and report back.

[JustinL]

I found the problem with the wiring. Either my harness is backwards or the wiring guide is backwards on http://www.microsquirt.info. My coax shield was wired to pin 32 and my coax center was to pin 33. I switched these two and now I have a steady 0 in trigger +/-. In fact the engine runs quite nicely now revving up to 2000RPM. I'm getting a lot of resets. Is the reason for these resets likely because I'm now using the coax shielding as the signal for my VR1 sensor? When I previously had the microsquirt controlling just fuel and not ignition I didn't get resets, so I'm pretty sure it's not the alternator or grounds.

[grippo]

There are actually 2 problems going on here. The first you appear to have solved by switching the wires on the VR cable. There were a few cables that had this problem and evidently yours was one of them.

The second problem is the resetting, which also occurred in your first datalog, before you switched wires. That datalog showed trigger+/- counting down, meaning you were missing wheel pulses, but it also showed the seconds resetting to 0, so the VR reversal is not causing the resets. I talked to Bruce about this and he said that a reset means there is something going on in either the +12 raw or +5 Vref signals. Any problem here might very well not show up on MS II but could show up on microsquirt just because it is smaller and therefore more susceptible to noise or dropouts. He suggests you put a large stereo type capacitor from the +12 raw signal to ground and see if that solves the problem.

[JustinL]

Problem 2 is now solved. It's a problem with my serial connection to the laptop. With the laptop unplugged, it runs like a champ! I checked the timing with a timing light and it's spot on. I'm going to pull an old laptop out of hibernation to see if it's the dynex USB-DB9 adapter or if I can connect with just the db9 connector. My Adapter is a DX-UBDB9 for future reference. In fact, it's only when I launch megatune that I get resets. If it's sitting idling with everything connected it purrs away until I doubleclick megatune.

On to tuning now!

Edit-- I tried the old laptop with a regular DB9 connector and still no luck.

[Bruce Bowling]

Problem 2 is now solved. It's a problem with my serial connection to the laptop. With the laptop unplugged, it runs like a champ! I checked the timing with a timing light and it's spot on. I'm going to pull an old laptop out of hibernation to see if it's the dynex USB-DB9 adapter or if I can connect with just the db9 connector. My Adapter is a DX-UBDB9 for future reference. In fact, it's only when I launch megatune that I get resets. If it's sitting idling with everything connected it purrs away until I doubleclick megatune.

On to tuning now!

Edit-- I tried the old laptop with a regular DB9 connector and still no luck.

Are you running a power inverter with the laptop? If you are getting resets from the serial then there is some sort of ground loop from the uS back to the laptop and back to the engine. If the car is on a battery charger and you are running the laptop off of A/C, or you are powering the laptop off of an inverter hooked up to the vehicle then you probably have a ground loop situation.

If you run the laptop off of a battery pack, do you get resets?

- Bruce

[JustinL]

Bruce, I do get resets with battery power. The car idles under it's own power with no battery charger as well, and I've taken it for a couple trips around the block. But as soon as I try to look at anything with megatune it starts throwing resets. I've actually started a more specific thread for this problem in the general section (trying to keep problems in the right sections/topic). Eric Fahlgren has given me a couple ideas to try, but we've had a big dump of snow... so my project is on hold for a couple more days.