The V8 Owners Forum -

Totally fine with a good thread hijack
I've previously used a relay coil to drive the tach. I'd highly recommend removing the switching bits of the relay as I didn't and the noise from it was quite audible over my engine!

It would be possible to build a circuit to give a larger pulse if needed. It is after all how the coil makes the pulse.

scudderfish wrote: ↑

Sat Jul 10, 2021 7:52 am

Totally fine with a good thread hijack
I've previously used a relay coil to drive the tach. I'd highly recommend removing the switching bits of the relay as I didn't and the noise from it was quite audible over my engine!

I'd be surprised if the relay could be heared over my engine but I'm with you on that. In fact I already have a relay butchered, er I mean modified, in this way.

DaveEFI wrote: ↑

Sat Jul 10, 2021 8:21 am

It would be possible to build a circuit to give a larger pulse if needed. It is after all how the coil makes the pulse.

If I don't get anywhere with the relay I have I may be looking for ideas. Larger coil than a relay but smaller than ignitionmaybe?

It's alive! It starts and runs for about 10 seconds before dying, but fundamentally it works

I've had it idling now. I had to fiddle a bit with the req fuel figure to get it ball park right. I had to stop it when the fan didn't kick in at the right time and it was heading towards overheating. I suspect I have air in the cooling system to bleed out as well.

scudderfish wrote: ↑

Sat Jul 31, 2021 3:57 pm

I've had it idling now. I had to fiddle a bit with the req fuel figure to get it ball park right. I had to stop it when the fan didn't kick in at the right time and it was heading towards overheating. I suspect I have air in the cooling system to bleed out as well.

If you need to alter the req_fuel by much at idle, chances are your dead time is out. Assuming you've calculated reg_fuel correctly, taking into account your fuel pressure.

DaveEFI wrote: ↑

Sat Jul 31, 2021 5:06 pm

scudderfish wrote: ↑

Sat Jul 31, 2021 3:57 pm

I've had it idling now. I had to fiddle a bit with the req fuel figure to get it ball park right. I had to stop it when the fan didn't kick in at the right time and it was heading towards overheating. I suspect I have air in the cooling system to bleed out as well.

If you need to alter the req_fuel by much at idle, chances are your dead time is out. Assuming you've calculated reg_fuel correctly, taking into account your fuel pressure.

My engine is a complete bitsa, running a 4 barrel TBI with 4 injectors of unknown origin and unknown flow rate I took the req_fuel figure from my MS1 tune as a starting point and then examined the logs. It was running until ASE dropped out (and lambda went lean) so I bumped up req_fuel until the injector time without ASE was at least what it was before with ASE to make it happier.

My next battle is my crank sensor mount. I've gone from a VR sensor to a hall-effect one. I bodged it into the mount I had previously made, but it was offset towards the rad by about 6mm and didn't really line up well. The engine runs, but I have a lot of dropouts to 0 rpm so I'm making a better one from scratch with more adjustability.

scudderfish wrote: ↑

Mon Aug 02, 2021 4:36 pm

I'm making a better one from scratch with more adjustability.

If you have any scratch spare could I have some? I make a lot of things from scratch and I'm running short.

Keep the updates coming always interesting to read about this stuff.

GDCobra wrote: ↑

Mon Aug 02, 2021 5:43 pm

scudderfish wrote: ↑

Mon Aug 02, 2021 4:36 pm

I'm making a better one from scratch with more adjustability.

If you have any scratch spare could I have some? I make a lot of things from scratch and I'm running short.

Keep the updates coming always interesting to read about this stuff.

You need to get a better cat. Endless supply of scratch if you need it. My cat is actually quite timid and gentle so I thought I'd better use steel instead. This is a mock up of what I'm planning to hang off the oil pump. Dimensions are all made up, I was just getting fed up of playing 3D Tetris in my head trying to figure it out. Flap disc in my grinder should make the welds look better when I make it.

scudderfish wrote: ↑

Mon Aug 02, 2021 4:36 pm

My next battle is my crank sensor mount. I've gone from a VR sensor to a hall-effect one. I bodged it into the mount I had previously made, but it was offset towards the rad by about 6mm and didn't really line up well. The engine runs, but I have a lot of dropouts to 0 rpm so I'm making a better one from scratch with more adjustability.

Are you getting 'sync resets'?
This is often caused by poor earthing strategy.
I had this and I followed an online 'expert's' earthing diagram. I re-wired to follow the official MSextra earthing wiring diagram and no more sync resets.

I also changed from firing the coils directly from MS - to an external Bosch coil driver and this helped reduce noise.

scudderfish wrote: ↑

Mon Aug 02, 2021 4:36 pm

My next battle is my crank sensor mount. I've gone from a VR sensor to a hall-effect one. I bodged it into the mount I had previously made, but it was offset towards the rad by about 6mm and didn't really line up well. The engine runs, but I have a lot of dropouts to 0 rpm so I'm making a better one from scratch with more adjustability.

You likely know, but Trigger Wheels do a sensor mounting bracket for the RV8. But may not be suitable depending on engine accessories like power steering pump etc position. But I'd stick with a VR sensor. Since they don't have electronics inside them, they tend to be more reliable than a hall sensor. But do require a dedicated circuit in your ECU for VR.

SuperV8 wrote: ↑

Tue Aug 03, 2021 7:38 am

scudderfish wrote: ↑

Mon Aug 02, 2021 4:36 pm

My next battle is my crank sensor mount. I've gone from a VR sensor to a hall-effect one. I bodged it into the mount I had previously made, but it was offset towards the rad by about 6mm and didn't really line up well. The engine runs, but I have a lot of dropouts to 0 rpm so I'm making a better one from scratch with more adjustability.

Are you getting 'sync resets'?
This is often caused by poor earthing strategy.
I had this and I followed an online 'expert's' earthing diagram. I re-wired to follow the official MSextra earthing wiring diagram and no more sync resets.

I also changed from firing the coils directly from MS - to an external Bosch coil driver and this helped reduce noise.

I'd stick to the same ground point on the engine that Lucas use.

The check as regards grounding is no sensor should have a ground with the ECU unplugged. Use a decent twin screened cable for the VR sensor, screen only connected at the ECU end. Keep it as clear of HT leads as possible, and make any HT leads that must cross it do so at right angles.

I should have really updated this. The problem was I had mounted a second processor (ESP8266) to act as a serial to wifi bridge. The emanations from this was doing silly things to the crank signal. Ripped it out and the engine runs with no drop outs. Self inflicted geek wound.