[fleagret]

Hi,

I'm swapping my triumph spitfire from megajolt to speeduino, so I'm only asking the speeduino to run ignition at the moment. I've swapped the megajolt, EDIS and ford coilpack for a speeduino 0.4.3.C (with vr conditoiner board) and vw smartcoil. For the most part its running, but I'm getting random short spikes to high rpms. This is seemingly intermittent occasionally not happening for several minutes, but can be as frequent as multiple times a second. Given the VR sensor and shielded cable are retained from the previous megajolt install I'm not sure they are the issue, I'm also getting a good signal from the tooth logger. Before I try and get another vr sensor could someone check I haven't done something silly in my tune that's causing the issues please?

Thanks in advance

[Rednaxs60]

This appears to be similar to the "RPM Break at High RPM" thread. An issue with a new install, and I have experienced it myself, is to ensure that the ECU grounds are correctly connected. Easy to overlook, and not be concerned with at the start.

I made a lot of assumptions with my project when I started my project. Can't discount anything. Just need a systematic troubleshooting routine, rule out one thing at a time. Just because it worked properly previously, is no guarantee that this will be the case as you go forward.

The sensor grounds and the main ECU ground must be separate. All unused ECU grounds must be connected to the main ECU ground. To check for this, disconnect the ECU from the wiring harness. At the wiring harness connector, check for continuity between the main ECU ground and the sensor ground, if continuity not good, need to rectify, if no continuity good, nothing else needs to be done. A small bit of installation maintenance. You may want to check for "dirty" noisy grounds and such as those from fuel pumps, rad fans and such. Move these grounds directly to the engine ground connection. You can also move these "dirty", noisy grounds to a different connection on the engine. The engine block is a good noise filter for grounds.

Once this small issue is verified, on to the next possible cause.

This video by Andy Whittle discusses ECU grounding: https://www.youtube.com/watch?v=EJ2TeodWDUE. Just a thought or two. Good luck.

[fleagret]

Thanks for the info. I've re-wired my as per that guide with the shielded cable run away from the coilpack and alternator. Earths for the speeduino and sensors are grouped together and connected straight back to the battery and the coilpack is earthed through the chassis separately via a longer path.

I'm still having issues with the system getting the odd pulse in rpm which seems to correspond with a sync error. This occurs despite having what looks to me like a good trigger signal without trigger filtering.
I've had other issues wihere the system seems to run for a short while before stopping generating any spark and needing a power cycle before it'll run again, so I'm not able to get any logging on the roads.

I'm only running the system for spark, so I've got MAP sensor connected, VR sensor running through the daugterboard vr conditioner, and a VW smartcoil pack.


Short datalog and tune attached, I'd be appreciative of any thoughts at this point!

Cheers

[LPG2CV]

The prefered method of wiring is to return sensor grounds to the Speedy board. Shielding should also only be grounded at the speeduino board end. Try shielding at the speeduino first.

[fleagret]

The prefered method of wiring is to return sensor grounds to the Speedy board. Shielding should also only be grounded at the speeduino board end. Try shielding at the speeduino first.

Thanks, that's what I've tried to do.

The Vr sensor cable shield is earthed to the speeduino board. The speeduino board main earth, all other speeduino board earth pins, and the coilpack connector earth pin are currently connected to a multi way busbar which is earthed directly back to the battery. The coilpck body has a good earth connection back to the chassis. The earth's do run past the coilpack due to packaging constraints in the engine bay, but I don't think this should be an issue.

This is my interpretation of the correct way to wire, from the various resources I've read. If there's something I've misunderstood and can improve then please let me know.

[fleagret]

I've sketched out the wiring as I've got it connected up.

[PSIG]

What has worked reliably for many - sensor grounds (signal return) should be at the ECM, on a dedicated sensor-only terminal, in order to prevent voltage offsets and other noisy or high-amp issues. Remaining multiple ECM grounds to the engine block or primary collector. Hi-amp and noisy grounds (e.g., shielding) to these primary ground points.

Sweep the vehicle in operation for EMI/EMR sources that could be causing interference. Use twisted-pair wiring where possible to balance or neutralize EMI. There are other wiring options for defense, but require deeper homework.

[LPG2CV]

In the tune, if you look at Settings - I/O Summary, you will see that there are no settings that are default settings.

This suggests to me that you did not load a base tune and instead just keyed values into TS. Speeduino needs a base tune to be loaded to set some values that are not available to the user.

You can download a base tune via SpeedyLoader. You can from SpeedyLoader, load fw that completly clears the eeprom if you wish. If you do so, you will need to re calibraate the sensors.

Looking a little more at the tune, you have it set to trigger high. More often than not it is set to low, but it does depend on the vr condition you have. you may also need to swap over the wires from the vr sensor to the board. So four possible combinations there.

The map readings look a little high at idle! This may improve with more tuning, or you may have a vacuum issue.

[fleagret]

What has worked reliably for many - sensor grounds (signal return) should be at the ECM, on a dedicated sensor-only terminal, in order to prevent voltage offsets and other noisy or high-amp issues. Remaining multiple ECM grounds to the engine block or primary collector. Hi-amp and noisy grounds (e.g., shielding) to these primary ground points.

Sweep the vehicle in operation for EMI/EMR sources that could be causing interference. Use twisted-pair wiring where possible to balance or neutralize EMI. There are other wiring options for defense, but require deeper homework.

Thank you. I think what you're saying is that the VR signal cable shield, and the earth from the smartcoil plug should both be earthed back to the chassis, and not to the Speeduino board, or sensor earth bar as they currently are. That and I need to look at the other RF sources, which I think is probably only altenator and coil pack, but there might be something else from the 50yr old loom!

[fleagret]

In the tune, if you look at Settings - I/O Summary, you will see that there are no settings that are default settings.

This suggests to me that you did not load a base tune and instead just keyed values into TS. Speeduino needs a base tune to be loaded to set some values that are not available to the user.

You can download a base tune via SpeedyLoader. You can from SpeedyLoader, load fw that completly clears the eeprom if you wish. If you do so, you will need to re calibraate the sensors.

Looking a little more at the tune, you have it set to trigger high. More often than not it is set to low, but it does depend on the vr condition you have. you may also need to swap over the wires from the vr sensor to the board. So four possible combinations there.

The map readings look a little high at idle! This may improve with more tuning, or you may have a vacuum issue.

Thank you for your comments, very useful. Yes, I set up a new tune from scratch. I assumed that tuner studio would give me access to all the variables, so good to know it doesn't and I'll start again by modifying a base tune. I'm not sure about the VR triggering, I've set to rising trigger edge as per the questionmark wizard which say to do that for a MAX 9926 vr conditioner, I'm working on a setup to interrogate the signal with a 'scope which should hopefully get that sorted.

As for MAP, I'm aware there's an issue - it's always had one and will be the focus of my problem solving once it's drivable and I can properly diagnose it. It seems to have no vacuum at idle, but starts to pull vacuume with small throttle openings. I'm pretty sure there's a small leak, which I will hunt down, but it pales into insignificance against the crank signal issue!