[gtrmonte]

This is standard 0.4 Speedy Mega board, on the Oct -2018 firmware.

Attached is the tune, and the log. It runs great, then develops a horrible sync loss and misfire at idle. In the log you can see as soon as I touch the TPS it goes away and runs smooth. As soon at TPS is back to 0 it misses again, then at the end of the log it completely clears up and runs great again.

Rumor has it new firmware means retuning the car, so I am trying to avoid that, as it actually runs pretty damn good as long as it isnt sync lossing. Which again, only at idle. It does occasionally cause the car to die if it decides to sync loss at a stop sign or something.

[PSIG]

I'm assuming VR sensors? Dirty (ferrous/magnetic trash) on wheels and sensors can commonly do that. Mis-adjusted sensors (distance, angle, wobble, vibration, etc), poor filtering or filter settings, and other stuff that affects the signal input would be typical places to look. Corroded cap terminals, poor connections on coils, rotor, or rotor phasing, dead noise capacitors (ignition coil and alternator) and of course cracked spark plugs, non-resistor plugs, and non-suppression or poor condition plug wires can cause EMI, affecting signals. I can't name everything that can cause EMI, but those are some of the more common ones.

General EMI on the sensor wire paths are another common source, so separating high current and signal wires often helps, as well as moving them away from other noise sources. Poor or missing grounds are probably the most common sources. One CRX we diagnosed with trigger issues had a poorly grounded audio amp as the primary culprit.

Because I can't test everything, I use a pocket O-scope as a probe using a short wire as an antenna, or a portable AM radio to listen for popping and buzzing as EMI detectors. Fix any noise makers. Shielding is a last resort after all other noise is found and removed. Oscilloscope traces of the sensor outputs, board inputs, and conditioner module outputs would be helpful for diagnostics if you can't find obvious hardware faults.

David

[EDIT] PS: Off-topic for your main issue, and I don't know your setup; but I see you're making heavy use of VE Table enrichment for accel (AE). That's fine, but when possible, we try to use TPS AE, perhaps blend MAP AE, and finally fill holes with VE cells to get the best fo each method when possible. If you have ITBs, supercharging or something else than stock-ish NA, then of course that plan may change substantially. What prompted you to use so much VE for AE? Just curious.

[gtrmonte]

Hey PSIG.

We are using a fully factory harness and only interfacing any wires at the OE ECU plug.

This is on a 240sx, using an optical sensor with an AEM 24-1 wheel in place of the Nissan 360-4 wheel that's comes stock.

I find it interesting that we only have sync loss at idle. I would think that as switching frequency rises within speedy, that's when I'd get interference.

I know signal strength on VR goes up with RPMs, but this Nissan optical sensor is just 'on-off' so I'm not sure.

I'm by no means a tuner. I'm learning rapidly.

A friend who is much better at getting cars to run than I am set up the VE based AE. Frankly worked a lot better than anything I managed to do with AE within the AE window. Since this is the old firmware, I don't have access to the Map based AE.

I was told that Map AE is much lower resolution than TPS, and in a perfect world we could blend them. Is that a new feature on the firmware that dropped today?

As far as the tune is concerned, I'm all ears on any advice.

[PSIG]

OK, and optical is digital, which is generally more resistant to EMI noise. Still, if you feel it is a signal issue, then some data would be very helpful from an oscilloscope or a digital analyzer. If you don't have either of those or a source to borrow them, cheap but useful USB digital analyzers are under $10 and 'scopes under $20 online. These tools can not only check your input signals, but also most of the outputs in order to verify they are doing what we and Speeduino think they should.

David

[CAnAm]

Hi David
What do I go looking for in terms of these tools?

@psig

[jonbill]

When did this problem emerge? Or has it always been there?
Tbh that firmware is incredibly old. Many many things have been massively improved since then. Including TPS AE.

[PSIG]

A "USB Logic Analyzer" is typically around $10US and up, ONLY reads DIGITAL signals under 5V, and connects to your computer/phone with free software to use and view. Very useful, usually with 8 channels, but limited by that <5V capability.

A cheap hobby-level and minimal "1-channel Oscilloscope" or better, runs around $20US and up for kits, $50 and up for pocket/portable versions, come with 1x leads to read up-to around 40Vpp typically. A version with optional BNC twist probe connectors is handy to use different probes to sense higher voltages (10x, 100x). Much more useful for more stuff, but more money the more you want. Many DS and DSO (Digital Storage Oscilloscope) 'scopes have handy features such as screen capture to share images, and more channels to compare in/out signals, etc.

For example, when away from the bench and working on the car, no extra cords are nice. I'm currently using an old DS202 2-channel rechargeable pocket 'scope ("2-ch DSO"). Originally under $100US, plus about $40 in extra leads and adapters. There isn't much I can't read for EFI and ignition, although it's a bit clumsy and often tedious to make settings being so small. Sure is nice when crawling under the instrument panel though. Pros and cons to everything. Make your choices for how you work.

[LPG2CV]

Don't rule out you may simple have an intermitant connection. At higher rpm the engine runs smoother. At idle it can move around a little more. This can emphasize an imtermittant fault. As the fault occurs, it can make the idle even more lumpy, and cause the fault even more.