MSNSPNP: 94 S/C Miata reset issue?
 

Friend finally installed his PNP and came over to have me help him tune it. Wired open the actuator for the supercharger to get some base tinkering done. We went for our first drive after getting his idle rock solid, and every once in a while Megasquirt resets. The gauges in megatune go blank, the reset indicator increases, the car stalls for 1/2 a second and the tach drops to 0.

Put the factory ECU back in and drove it for over 2 hours without any problems in drive ability. Doesn't make any difference what you're doing when it happens w/MS installed. Turning, going straight, bump, smooth surface.. Its not a problem with the car, I'm 99% sure. Anyone else ever had this problem with a PNP? Going to try and reflash DIY's firmware and see if that helps. Anyone??

Never had this problem, but perhaps it's a grounding issue? The ECU grounds for the '94 are underneath the throttle body. Check and clean them and see if anything changes.

That was oddly the VERY first thing I checked. Gonna try and clean it though and see what happens. Noticed he had the ground in trunk by the battery disconnected, so we fixed that already. The engine is grounded to chassis with a 4 gauge battery cable.

Hes on his way back over again, we'll clean those grounds and post results. *cross fingers*

Had him clean the crap out of the grounding post and ring connector for the grounds below throttle body, and make sure they were good and snug. After that was complete I went ahead and flashed the firmware into MS again.

Started the car and drove it for 20 minutes before it reset again. After 2 hours of driving it only reset 3 times total. Still kind of bugging me, it shouldn't be doing that.

We've got some other issues to look into; Throttle won't indicate < 10% or > 77% closed/open...

Going to have him make a rather large ground wire to attach from the ECU grounding spot under TB to the chassis and see if that helps the resetting..

The throttle just needs to be recalibrated in software. It's under the rightmost drop-down menu, tuning I think?

Resets can be tricky, and you should be getting none at all. Never. Nada.

The only time I ever got actual hard resets was when I stupidly had a relay coil paralleled with an input to the MS, every time the relay de-energized, the spike caused reset- dumb wiring mistake.

DIY sometimes suggests that a large (3,300 or 4,700uf) cap be placed on the main MS board between +12 and GND. Specifically, +12 is taken at S12C or the striped side of D10.

Beyond that, grounding. I ran two ground wires direct to the head, in addition to the ones on the ECU harness that I re-used.

Yeah I tried recalibrating the TPS three times, still won't close. Since I'm leaving town again and won't be able to help him anymore I left instructions to remove the throttle body inlet elbow and have someone manipulate the throttle, after he backs out the idle screw. Make sure it closes all the way and opens 100%. Since the TB has been moved over to the inlet of the supercharger I thought there might be something sticky or off whack with the throttle cable / linkages. He was planning on taking this off anyway to add a tiny meth injection nozzle to the supercharger inlet in hopes of cooling the bearings / charger / charge off? I Don't think its worth the effort, but we'll see. Also told him to install the IAT sensor at the manifold inlet position before we start tuning for boost.

Other thing that enters my mind.. Just made him replace the 'extension' harness for the TPS which was compromised by the cam gears causing it to run funky.. So maybe the TPS shorted out or is bad? If he can't find anything wrong with mechanical aspect of it, I've got a spare TPS to try.

We're making progress on the reset issues though, thankfully. Once he gets that beefcake ground installed we'll see what happens. I didn't think what we did would've solved the problem.

Should the PNP unit be grounded to the chassis behind the seat well, or is it okay to just mount it on the painted surface? For my boomslang style harness I broke out grounds incoming from the cars harness straight to ground, then coming from megasquirt straight to ground.. Plus added 3 - 5 others under the hood. Had too many problems in the past with cars and grounding issues... Figured I'd cover the bases.

my PNP used to just sit on the carpet and never had a resetting issue.

Mine is just setting in there too. I'm going to velcro it to the floor. I have never had a reset issue.

Just a thought. I had all types of crazy things going on when I was using my Vista computer. I'm sure your not using it. But if so, try a different computer. As soon as I switched all the weird qirks fixed on mine.

Could you post a data log with some of the resets? They may have a couple of clues about what's causing them.

Also, it is best if you don't ground the MSPNP case at all.

Hmm. Even if the TPS is physically jammed in such a way that it won't fully open or close, you should still be able to get it to read 0-100% in MegaTune. That's the whole point of the calibration process- to scale the input appropriately, taking into consideration that a TPS will rarely if ever be built and installed in such a way as to actually provide an exact 0-5v output. They're usually designed such that the throttle motion does not actually cover 100% of the potentiometer's range.
If the "wiper" lead was shorted out, then it is possible the wiper and element could have been damaged by overcurrent when the wiper moved to the +5 side of the element. This would tend to be exemplified by a very jumpy reading, with skips and spikes, when viewed in the RealTime display.

Well I have several logs I captured from last night for some tuning and I know all three resets are captured in the logs.. The problem is, they're all HUGE HUGE logs and I don't know how to identify for sure when it reset aside from watching it playback in Megalogviewer to watch for "RUN" to switch from yes to no.. Hints?

Joe, I'm still stumped on the TPS issue. Think we'll try a new TPS and see what happens.. The realtime and logs both show smooth linear operation.. Highly confused.

Resets appear in MegaLogViewer as vertical red lines so they stand out a bit.

Ok this weekend we will test everything again, IAT will be installed and found my big mamma jamma ground hidden by piping under the heatercore hoses had rust on it from previous water leak, cleaning it off tomorrow and hopefully have a successful venture this weekend.

Cool, Thanks Matt. I'll look for it and post it up when I get home. Guess I've never had a reset logged before that I noticed.

http://www.jugrnot.com/reset.jpg

The cursor is over the reset right there so I could show what was happening at the moment of reset. Reviewed ALL fields before and after reset but I don't see anything in there that would cause it. Battery voltage is pretty steady 13.8 - 14.6 and I see no abnormal spikes or any other indicator. Anyone else see anything strange?

Thats the very second data log, so its untuned grossly at this point, I know. ;)

http://www.jugrnot.com/reset2.jpg

This one is a lot more telling...

Before the reset:

RPM: 2320
MAP: 45
CLT: 184
MAT: 98
AFR: 16.1
PW: 4.1
TP: 15
Spark: 24.8
Boost: -7.4
Battery: 14.1

During the reset:

RPM: 2366
MAP: 113
CLT: 119
MAT: 79
AFR: 15.246
PW: 6.0
TP: 30
Spark: 24.8
Boost: 2.466
Battery: 15.8

I'm puzzled.

Just as an FIY (and probably unrelated to your reset) it looks to me like you've got trouble with your crank/cam sensor input. See that huge spikey section in RPM in the first log, and the fact that max RPM was recorded as 12,xxx in the second? That strongly suggests trigger trouble.

Could you post the whole file? These are often more helpful than a screen shot.

Thanks for pointing that out, Joe. The first time we tried to start the car it wouldn't. No RPM input. Come to find out, one of the wires that were cut for an old timing controller that didn't get patched back together. Since then we've made 100% sure everything was back together correctly. Think it could just be getting noise from a butt splice behind the seat?


Matt: Crap, Sorry! I thought I posted the whole file, forgot;

http://jugrnot.com/datalog200809012044.xls

There is a single reset in the log, and it's a real one. There isn't anything to suggest its cause though.

The RPM readings look pretty steady to me - a little jitter, but not much of any spiking.

Is this an MSPNP, or a DIY MS setup for PNP use on your Miata? If it's an MSPNP shoot us an email and link to this thread, include all of the information on the label on the bottom of the unit, we can tell from that if it's got that large cap on the 12v input already, which willl help make the units pretty reset resistant unless you've got major ground/12v issues or something else funky going on with your harness maybe. Shoot it over to websales@diyautotune.com

Matt and Jerry:

Thanks for helping out. I'm going to have Andy send you guys the version number in an email, its a PNP from you guys. At this point I'm seriously doubting its something directly with the megasquirt unit. We cleaned the ECU grounds and drove around all day yesterday in the shitty rain. Early in the day had 3 resets in pretty quick succession, then drove another 5+ hours total without a single one. Still on the list is to add another ground from the ECU ground to chassis and see if that helps things a bit.

I'm also happy to report with the factory loaded timing and fuel maps we've already started to tune for boost, and its been a piece of cake. I was really worried about how well it would work out since I've only tuned two N/A cars on megasquirt thus far. What you guys provided for the base maps with minor adjustments has been an excellent place to start for 8psi supercharger. :D

MSPNP MM9495 v1.01 rev C

Email has been sent.

That's currently the latest revision and should be fairly reset resistant. It's got a large cap on the 12v feed to smooth out the rather noisy 12v power available to the ECU which in most cases helps even if your grounds are weak. We'll still be glad to take a look at the ECU if you do suspect it at some point. Is it possible you have any damaged wiring, or noisy ignition modifications placing coils/plug wires along EMS wiring?

At any rate, glad to hear the base map was a good start for your tuning, that was the goal!

No damaged wiring as far as I know had a few cut wires from before but all is solid now, Just installed another heavy duty ground from the ecu grounding point to chassis, about to go drive some more and see if anything happens. Will probably install a 2nd heavy duty ground at another point later today. Thanks for all the support and replies guys!

Andy

I have another observation that has me scratching my head:

http://jugrnot.com/slippingbelt.jpg

Very bottom graph, the dark red... are those HUGE voltage fluctuations normal? I actually never checked voltage in logs from my miata...

That's pretty big. While MLV zooms in and that can make some signals look noiser than they should be, your battery voltage signal is pretty noisy. I think there's a charging issue here.

Well, I took my lovely 217K mile alternator in today to get tested, well it passed on Oreilly's machine, a few buddies work there so we hooked up a multimeter and ran the tests again to get specific numbers, well it's putting out 14.9 volts and jumps to 15.3 volts and it puts out a whopping 12 amps.

How about the voltage regulator - how well is it working?

Not sure how to test the voltage regulator in the alternator, but new alternator comes in tomorrow.

Tossed in brand new alternator unit. Changed nothing.

At this point, we've started adding grounds. The number thus far is around 10 new grounds in various places on the car. So far today since we stopped working on it, we haven't seen a reset yet. Will post back soon if that changes.

Guys I want to thank all of you for responding and helping me out with this issue. After adding a ton of grounds anywhere and everywhere the problem seems to have stopped the last two days the car has run AWESOME! If anything changes i will update. Thanks again.

Andy