MicroSquirt.com read only forum (Jan.15,2018)

OK guys,

I’ve got some specific questions related to MS2 and the wheel decoding setup. I did “kind of” ask these on another thread, albeit it was a bit of a hijack of a totally different thread so I thought I’d start another. So, sorry for the semi cross posting, I hope nobody minds as this should be clearer.

I have just got my car (4 cyl) running with V3.0 MS2 2.54 running my fuelling from a 36-1 VR setup. On this same car I am running EDIS for ignition from an MS1, reason being I need the MS2 to be fuel only for some fuel only code testing in the near future. Anyway for the sake of this post please ignore the fact I’m running fuel only as I have some MS2 ign related questions …

My 36-1 wheel and VR combo is set exactly as per the EDIS 4 requirements with the sensor/tooth alignment as shown in attached pic. Missing tooth is dead opposite my sensor 90* BTDC #1.

I know the following is correct for the wheel decoder settings:

Trigger wheel teeth 36
Missing teeth 1
Skip teeth 18

But I am not sure what I should be running for the delay teeth. If I use Al’s description to the letter I believe it should be 28 as the crank has to rotate a full 270* (27 teeth) from TDC #1 for the missing tooth to align with the sensor. Then go another 10* for the sensor to line up with the first real tooth after the missing one. Therefore it should be 28 teeth (from the 280*).

Is that correct?

James M has suggested I use delay teeth = 3 and trigger offset = 60. I have to be honest here James and say I don’t follow this. The trigger offset is confusing me.

Can someone please explain to me the relationship between delay teeth, trigger offset and how these values control when the MS gets a Tach signal? For example, when will my spark occur with delay teeth = 28 and trigger offset = 0. Would this give an ign event at TDC #1 ?

The next question relates to the trigger offset. The docs say this may be used for the cranking advance figure. Does that mean this should be kept between say 5-10 degrees for reliable easy starting? I know we can enter -90 to 180. Surely this would cause all sorts of starting problems? Could someone explain this, I am obviously missing a key point somewhere!

Many thanks

Dan

danc8000,

Delay teeth and trigger offset have a similar function - they both set an offset from the tooth to the TDC.

With missing teeth wheels, the delay teeth is important though, as it also sets what is considered a 'tach' tooth (one that is used to create an ignition event), and all the remaining 'tach' signal teeth must occur on real teeth.

So the intent is to set the delay teeth to the number of teeth after the first missing tooth when at TDC, and use the trigger offset to set the difference between the observed and actual timing. So delay teeth = 28 sounds right, and you would then use the trigger offset to calibrate the ignition using the trigger wizard.

The trigger rise will send the spark at the 'tach' teeth-trigger offset, which should depend on the position of the sensor relative to the crank wheel and can be determined by observing the difference between the actual timing (on a timing light) and the timing commanded in MegaTune - you enter the trigger offset that eliminates this difference. That tells you how far the tooth is offset from TDC, and the cranking spark will occur at the trigger offset value (i.e., if it is behind by 1/2 a tooth at TDC, then in your case you would get 5° advance, etc.). .

Lance.

I just want to point out that you can't specify the EDIS option with wheel decode - I have no idea what might happen with this combo. I have no reason to think you are doing this, and I know you aren't controlling spark from MS 2, but just want to make sure you set the non-EDIS option with the wheel decode even for fuel only.

Thank you Lance, that's cleared that all up very nicely.

Al, thanks for the note on not setting EDIS. It's running with it set at std coil charging so no problems there. Appreciate you pointing that out though.

I have two other related questions I could do with some help on - the subject of one of them always gets dismissed and boo'd at but no harm in asking I guess!

1. Trigger offset: If one was running ign and fuel from MS2 with a 36-1 exactly as above diagram (alignment wise) with delay teeth = 28, the trigger offset (if everything is lined up spot on) should be zero, correct? I read in the docs that the trigger offset is what may be used for the cranking timing value. Does that mean one should always try to get a trigger offset in the range of 5-15 degrees for reliable starting? If so would it be better (with the wheel/sensor alignment staying the same) to alter the delay teeth value to something like 29 and a trigger offset of 10 degrees?

2. Fuel timing: Can you tell me with this same 36-1 setup with delay teeth = 28 and trigger offset = 0, when should the start of the injection period be? I know we don't have a seq system here but for what I am trying to do, I need to know when the inj pulse should begin relative to say TDC#1 (let's assume 1 squirt per cycle). Would it be close (within the resolution of the code etc) to TDC#1 for example?

Thanks for any feedback guys, as always very much appreciated.

Dan

Has anyone got any thoughts on these two questions?

danc8000,

As Al says, you either run EDIS OR the wheel decoder, not both. I assume you are running an EDIS wgheel, but not the EDIS module.

For EDIS, the EDIS module sets the cranking timing.

For the wheel decoder, cranking timing is set at the trigger offset if you have selected trigger rise. If the sensor alignment is 'perfect' this will be zero. Personally, I would go with a delay teeth of 28 and an offset near zero (as required to calibrate the timing with the trigger wizard) rather than mess with the delay teeth, etc. Zero is fine for cranking.

The fuel will be injected on a 'tach tooth' ± the trigger offset. If the delay teeth is correct (i.e., putting the tach teeth at TDC), then you will have the fuel injected at the trigger offset. So it will be near TDC, but it may be on the compression stoke or the exhaust stroke.

Lance.

Hi There!

We are installing v3.0 msII to the Renault 5. It has wheel with VR sensor like attached gif. Is firmware 2.5+ can handle that? What wheel decoding settings should be set.

Actually, at first we have already tried to run it with v2.33 embled code but no success. Then we changed it to Hall sensor in the distributor and neer to get success, but anyway as currently wheel decoder is availalbe I think better to turn it back to the VR sensor on the crankshaft wheel.

Thanks,
Igor

MS II will not run with that wheel for 2 reasons. It has 2 pairs of missing teeth, plus it looks like it also has a long tooth after the missing tooth.

Yes. It has 2 pairs missed tooth and long tooth.

Then the question, if anounced router is supposed to handle that?

But anyway, we are happy! Engine is running. MSII rocks!

Yes the router will handle that.