Ian,

Thanks for your time.

The car was chocked--on the ground, not moving, emergency brake was probably not on. I did notice the laptop reading 23 mph once, and we certainly were not moving. I did not even know there was a VSS that needed calibrating. In looking at TS, VSS 1 is Off, VSS 2 is Off, Shaft Speed Sensors 1 and 2 are Off, and VSS Output is off. My guess is it has been set up like that since I got the MS3 Basic from Rev four years or so ago. (She's been tuned four times at two different places. Initial naturally aspirated tune, retune for squaretop, retune for the Rotrex install, and retune when I changed the intake tubing to the Rotrex.) If VSS is Off, does that still indicate a ground issue? If I need to turn it on, please let me know which one(s) and anything else useful. What would VSS being off cause, supposing everything else was working fine?

I checked the ground to the tranny/block beneath the heater hoses, the ground underneath the throttle body, and the grounding pack under the dash. All seem fine. Are there others?

TS says Mainboard Injectors Bank 1 Dead time @13.2V(ms) is 1.000, with Correction Curve 1. It also says MS3X Injectors (at the top of the pulldown) Dead time 0.630, Curve 1. I'm running the Flow Force injectors, new beginning of last year with the Rotrex install.

I just installed new Magnacore plug wires. They're maybe a week old.

Thanks again,

When you say you checked the grounds, does that mean you wiggled them or completely unbolted both ends and scuffed the contact surfaces and replaced them?

I pulled and replaced the engine. Both the grounds I mentioned under the hood were completely removed. I cleaned them then, which was only about a month ago. Yesterday, I just checked they were secure. I can do what you suggest again. The car is basically waiting for its next event, Feb or Mar 17 at the earliest. Plenty of time to check things.

Are there other grounds susceptable to the elements that I have missed?

Thanks,

The calibration is done in the "speed and gear sensors" menu, mine is set up as type "digital", input "PE2 Flex", diameter "1.9", type "pulses per mile", pulses "40,000", and "smoothing" of 50. I dunno if that's what all NB MS3s use, but it's something to look at it. I would expect that if the VSS is configured as "off" then the software should always output "0" for vss, but the MS3 code doesn't always follow the best software development practices... Might be worth trying to set it up and see if it makes the random values go away, it's possible that even when set to "off" it's running in some kind of analog mode that's trying to make sense out of random noise on the input line.

Those are all of the dedicated ground wires that I'm aware of in the car. OTOH, there are ground wires running to the ECU and all of the sensors in the car, and if any of those is damaged it could produce strange effects like this too. IIRC the VSS sends an analog signal to the gauge cluster, which interprets it and then sends a digital VSS signal to the ECU. I assume the speedo needle was sitting on zero and not wandering around while idling?

--Ian

I just noticed under Gear Detection in the Speed and Gear Sensors Pulldown, VSS/RPM is selected. and the number of gears and their ratios are input.

Yeah, that's so that the MS3 can know what gear you're in, by comparing VSS and RPM, it's used for boost-by-gear or other things like that, I think. I'd be surprised if it had any effect on this.

--Ian

If I were to turn it on and mess it up, would anything bad happen?

AFAIK the MS3 doesn't actually use the VSS value to compute anything critical, it's only used for extra features like displaying mpg and for logging. (It is quite useful in datalogs, though).

--Ian

I have not had a chance to look at your logs, but something helpful you can do when logging is hit spacebar in TS. This will cause a mark in the log so you know where to look. If you have not been doing that I would suggest giving it a try so we have specific places to look in the log. A good thing to do would be to hit the space bar a certain number of times and jot down what is going on. So then we could go to that specific part and the log and be able to see what you think is happening.

In post #55 there's a log from 14:22. Please take a look at the scatter plot. Does that mean anything?

Thanks,

Calculate gear using RPM and VSS.

EDIT: Duh, that's what you just said a few posts up. In this one you said, "nothing critical"... Agreed.

Like many technical people, I'm reading from the bottom up.

I mentioned in a previous post I replaced the coils with an unused spare set that had been given to me my the previous owner six years ago. I can't call them new. I don't know how old they are and was concerned one or both might be malfunctioning, so I obtained another used but functional coil pack. Installed last evening. It was dark and I decided not to take her for a ride. These logs are just idling in the driveway. No other changes or fiddling but the coils.

When she started idling rough, I got out the timing light again. #3 still had a weird pattern, but this time it was flash, flash, flash, long flash, flash, long flash, instead of flash, flash, blank, flash...

I've got the package tray carpet out and the cover off the fuel pump area. When it started running rough, there was no change in the sound coming from the pump. Can I assume the fuel pump is good?

Any advice would be greatly appreciated,

Gents,

I'm out of ideas. I really need a hand here.

I spent what seemed like forever cleaning/polishing/kissing and loving the grounds under the hood. She seemed fine when I started it up, so I was going to go for a ride and log some data. Unfortunately, she started running like crap before I even started out of the driveway. Very labored idle. I revved the engine slowly, and at about 1300 rpm she seemed out of balance. I fanned the throttle a couple of times, and at the end of the log, you'll see it just died. The fuel pump kept running for a second or two afterwards.

To recap,she's got new plugs and wires. I've tried three coil packs, three different fuel pumps, and two alternators. I've cleaned all the grounds. The crank position sensor is new. Rotrex and Flow Force injectors installed early 2015. I just swapped in the bottom end from a Japanese Domestic Market importer, replacing my 143,000 miler with one at about 60,000. When she's running right, she's a beast.

Thanks,

Sooooooooooooooooooo, I replaced the pretty new crank position sensor with the one that came with the JDM motor. I was dancing in the garage after about 20 minutes of smooth idling, but my dreams were dashed. She started running like shit again. Dammit. Now, I'm completely outta spare parts to try...

Please take a composite log when it's running shitty and post here.

I don't think it's a sync loss issue. It's showing lean on the wideband, even though it claims to be injecting fuel. Either it's misfiring with a bad spark, or maybe there's an injector that's misbehaving.

--Ian

There's the -not 100% reliable- report from the timing gun that spark is flaky. So it's likely to be spark related.
My best guess at this point is wiring.

That last log finally captured the engine dying. Are there any clues in that?

A few other questions.When I was cleaning grounds, I found that part of the wire bundle to the wideband was scorched by the header. However, no wires were showing, and the wiring was well clear of the header during that last run. If that wiring is actually damaged, could it cause the problem?

I modified the harness to extend the wiring to the water temp sensor when I did the coolant reroute. Is there anything strange in that last log related to coolant temp?

Anything else I can try?

Thanks,

Are you running sequential ignition?

Rev,

I hope you and yours are well.

Under Ignition Settings, in the Ignition Options/Wheel Decoder tab, the Spark Mode pulldown has Miata 99-05.