Issue with wasted spark ignition

General Chat About Electrics, And Ignition Systems.

Moderator: phpBB2 - Administrators

DaveEFI
Forum Contributor
Forum Contributor
Posts: 3991
Joined: Fri Feb 26, 2010 4:27 pm
Location: SW London, UK

Post by DaveEFI » Mon Aug 07, 2017 9:49 am

Depending on the tach input circuitry, you may need an external pull up (or pull down) resistor.

Some hall effect sensors are quite temperature sensitive. Some have an upper limit below what you could see under bonnet.

If it were a regular misfire the type of sensor would be suspect, though. But an occasional one like this is going to be difficult to find.

EDIS is just about the most reliable ignition system ever made - and that uses a VR sensor.


Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

minorv8
Knows His Stuff
Knows His Stuff
Posts: 477
Joined: Thu Nov 23, 2006 5:10 am

Post by minorv8 » Mon Aug 07, 2017 9:53 am

The software has an engine data page when you can see the rpm, trigger count etc.

With the first Hall sensor the starting rpm was around 2000 rpm i.e. a bit excessive. That was my mistake, I did not check the Honeywell data sheet. It required at least 10 mm gap from tooth to tooth. The gap on my trigger wheel was less.

My friend has the same E6X in his supercharged Mini with 60-2 triggerwheel. I checked which sensor he is using and bought a same Opel/Vauxhall sensor. That read the rpm correctly but apparently did not read the missing tooth since it would fire only some of the cylinders. I used a timing lamp to check which cylinders fired which did not.

The VR sensor fixed these problems and the engine fired instantly and started behaving as it should.

The VR sensor is a Ford Zetec sensor.

Settings are as per the E6X manual states.

I have played with the VR sensor gain and filter settings in the sofware. I got them wrong and the engine did not run past 4700 rpm at dyno.

Again, please remember that I can trash the engine all day long past 6000 rpm and it runs flawlessly. It is only when cruising at steady speed that this occurs.

User avatar
stevieturbo
Forum Contributor
Forum Contributor
Posts: 3508
Joined: Sat Nov 18, 2006 6:22 pm
Location: Northern Ireland

Post by stevieturbo » Mon Aug 07, 2017 9:53 am

There are reliable systems all over the world that use either sensor. As proven by millions of OEM engines that use either.

But obviously all parts need to work together, when you start using a selection of different parts then hope to get them working together, problems can occur.

Not all sensors are the same, not all VR sensors are the same, not all hall sensors are the same, nor is the ecu circuitry within whatever they are attached to....and indeed the wiring it'self, and its routing and environment

Depending how annoying the problem is, changing one thing at a time and just going with that to see if it changes is probably best approach as if you change a lot of things you might never know what fixes it ( although if its fixed you may not care lol )

But the above is why using an OEM hall, with it's matching trigger wheel is usually best. It gives a simple clean square wave output regardless of rpm. No f***** about which if you're having problems....matters !
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

User avatar
stevieturbo
Forum Contributor
Forum Contributor
Posts: 3508
Joined: Sat Nov 18, 2006 6:22 pm
Location: Northern Ireland

Post by stevieturbo » Mon Aug 07, 2017 10:03 am

minorv8 wrote:
Again, please remember that I can trash the engine all day long past 6000 rpm and it runs flawlessly. It is only when cruising at steady speed that this occurs.
When DTA released their S series 10 years ago, they deliberately built the metal case isolated from all electrical parts....seemingly some morons in the past managed to short the ecu case on things like batteries etc so he deemed it safer to fully isolate the case on the new ecu

However in some small cases...and I think mine was the first, at low loads, very random the engine would do almost what I think you're describing. This tortured me for ages. Allan eventually said to earth the ecu case. This resolved the issue.

Again...it points to an interference issue somewhere. Again check wiring...VR should use twisted screened pair. Route nowhere near any HT wiring, always use resistor spark plugs.
I've used a Ford VR sensor myself for many years too without any problems...but on a wheel supplied with tooth sizes etc to suit.
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

DaveEFI
Forum Contributor
Forum Contributor
Posts: 3991
Joined: Fri Feb 26, 2010 4:27 pm
Location: SW London, UK

Post by DaveEFI » Mon Aug 07, 2017 5:13 pm

Certainly with MS setting the zero crossing point wrongly in the tach input can result in it cutting out at highish revs. But that will be constant - not intermittent.

You need some way of looking at the signal the processor is getting from the tach sensor and input circuitry. To see if there is a disturbance when your fault occurs.

Is the car rev counter showing something odd when the fault occurs? If the ECU isn't seeing pulses or any other ignition funny, the rev-counter won't be getting the correct pulses either.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

minorv8
Knows His Stuff
Knows His Stuff
Posts: 477
Joined: Thu Nov 23, 2006 5:10 am

Post by minorv8 » Mon Aug 07, 2017 6:18 pm

Yes, it shows a slight drop of revs.

One thing that I have forgotten. Several hours on rolling road and it never did this :D

DaveEFI
Forum Contributor
Forum Contributor
Posts: 3991
Joined: Fri Feb 26, 2010 4:27 pm
Location: SW London, UK

Post by DaveEFI » Tue Aug 08, 2017 8:20 am

What sort of air gap has your VR sensor got? Have you checked that on several teeth - to see what the run-out is? And that there's no wobble on the trigger wheel?
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

minorv8
Knows His Stuff
Knows His Stuff
Posts: 477
Joined: Thu Nov 23, 2006 5:10 am

Post by minorv8 » Tue Aug 08, 2017 10:11 am

Can´t remember the exact air gap. Less than 1 mm in any case. I checked the run-out when I fitted it and it was pretty much zero.

Bracket is made of 5 mm angle iron, bolted and pinned into the timing cover.

DaveEFI
Forum Contributor
Forum Contributor
Posts: 3991
Joined: Fri Feb 26, 2010 4:27 pm
Location: SW London, UK

Post by DaveEFI » Tue Aug 08, 2017 10:36 am

I generally set them at 1mm. Although it's not usually too critical. Plus or minus 0.25mm Unless Haltech say different.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

User avatar
stevieturbo
Forum Contributor
Forum Contributor
Posts: 3508
Joined: Sat Nov 18, 2006 6:22 pm
Location: Northern Ireland

Post by stevieturbo » Tue Aug 08, 2017 11:44 am

Again it all depends on the sensor, wheel diameter, tooth size/pitch etc...

That's why hall is almost always more reliable. They either work, or they dont. VR being a variable voltage and more susceptible to interference through bad wiring etc....just has more failure options.

Although if you pick an OEM wheel and use the relevant sensor that's usually a good starting point too.

Maybe it's resolved though...or just run it on the dyno all the time :P
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

DaveEFI
Forum Contributor
Forum Contributor
Posts: 3991
Joined: Fri Feb 26, 2010 4:27 pm
Location: SW London, UK

Post by DaveEFI » Tue Aug 08, 2017 3:54 pm

It's one of those faults which is very difficult to guess at a fix for.

If it is a tach signal fault, you need to see what it looks like at the processor, input circuit and sensor - to see where corruption is occurring.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

SuperV8
Knows His Stuff
Knows His Stuff
Posts: 749
Joined: Tue Jul 07, 2009 11:25 pm
Location: West midlands

Post by SuperV8 » Thu Aug 17, 2017 11:53 am

How are you firing your coil packs?

Could be getting electrical noise in your sensitive circuits?

I had a problem similar to yours (although i'm using MS) random 'hiccups' when cruising, it may have happened at higher RPM but it wasn't noticeable. I was getting noise in my crank signal from the MS firing the high current coil packs internally, which used to be when they recommended for ease of setup. Now they recommend using an external coil module for dumb coil packs which only needs a small logic signal from your ECU.

Tom.
Dax Rush 4.6 supercharged V8 MSII

minorv8
Knows His Stuff
Knows His Stuff
Posts: 477
Joined: Thu Nov 23, 2006 5:10 am

Post by minorv8 » Thu Aug 17, 2017 1:41 pm

Separate igniters.

Too much work at the moment to continue with testing things...

Here´s a photo showing the igniters and coils. Halfway thru the conversion, carb still fitted.

Image[/img]

Post Reply

Return to “Electrical & Ignition Area”