Honda K series Crank & Cam Type

HondaDrag
Posts: 60
Joined: Wed Mar 06, 2013 5:12 pm

Re: Honda K series Crank & Cam Type

Post by HondaDrag »

Yes will do them and let you know, Thanks alot.
pavlo
Zen Performance
Posts: 407
Joined: Mon Aug 04, 2008 10:18 am

Re: Honda K series Crank & Cam Type

Post by pavlo »

Have you set ignition 1-4 outputs to be TTL with 5v output?
HondaDrag
Posts: 60
Joined: Wed Mar 06, 2013 5:12 pm

Re: Honda K series Crank & Cam Type

Post by HondaDrag »

I have set Required spark output to Normal not TTL and output voltage to 5.8v.
Thanks
pavlo
Zen Performance
Posts: 407
Joined: Mon Aug 04, 2008 10:18 am

Re: Honda K series Crank & Cam Type

Post by pavlo »

There is your problem!

It's firing on the wrong edge as it will float high and then be pulled low for the dwell time, but the CDI fires on the falling edge which is at the beginning of that cycle.

You have two choices.

Set it to TTL (assuming board is hardware capable) and fit pull down resistors to be sure.

Change M&W CDI to rising edge and check (hope) that the timing is consistent, or in otherwords the output voltage floats up in a consistent manner.

I would try the latter as it's just a jumper on the CDI, and check it with the light, but if doing this from scratch I would go TTL.
HondaDrag
Posts: 60
Joined: Wed Mar 06, 2013 5:12 pm

Re: Honda K series Crank & Cam Type

Post by HondaDrag »

All solved Paul good job :).....just set the M&W jumper to rising edge and timing went steady. So normal setting for the S8 is rising edge and TTL is falling edge than.

Now I have some small issues but will write on another new topic.
Thanks again.
pavlo
Zen Performance
Posts: 407
Joined: Mon Aug 04, 2008 10:18 am

Re: Honda K series Crank & Cam Type

Post by pavlo »

No not quite.

Normally you only use TTL as an input to a CDI. Normally you use the non TTL to drive a coil directly with no amplifier, and to be honest if you wanted to get rid of the CDI you could in most applications where you're not using lots of boost and/or methanol.

What you have ended up with works by pure luck given the combination of the components you have, the CDI unit probably has a pull up on the input, and then the pulldown nature of the normal ignition works fine, but if you were driving an amplified coil for example, it will not work.

As an aside you should probably put the max gap checking on, and tweak the max gaps to be large enough that it doesn't cause any problems.
HondaDrag
Posts: 60
Joined: Wed Mar 06, 2013 5:12 pm

Re: Honda K series Crank & Cam Type

Post by HondaDrag »

If thats the case than i will tweak the wiring with the resistors and switch to TTL output and re-do the timing, I dont want to play with luck.
I will eventually need the CDI as the engine very soon will be on 100% ethanol and will see lots of boost :))

I dont know what you meant Paul by this, can you help me abit more?
As an aside you should probably put the max gap checking on, and tweak the max gaps to be large enough that it doesn't cause any problems.
Cheers
pavlo
Zen Performance
Posts: 407
Joined: Mon Aug 04, 2008 10:18 am

Re: Honda K series Crank & Cam Type

Post by pavlo »

I don't think that's necessary. If it was mine I would be happy to leave it as it is. I would check the voltage on the input to the CDI without the engine running and check that it's steady. If it's pegged at close to 5v then you can be pretty sure it has a pullup on it, and that will work absolutely fine, it's just the opposite of an active high output and a pull down resistor.

The main thing is to understand how and why it works.
pavlo
Zen Performance
Posts: 407
Joined: Mon Aug 04, 2008 10:18 am

Re: Honda K series Crank & Cam Type

Post by pavlo »

You mentioned you turn off "max gap checking"

Turn it back on now the gap setup is correct, if you occasionally run in to some gap errors, you can tweak the maximum and minimum cap tables to avoid the errors in normal running, that way if something does go wrong it will detect it straight away.
HondaDrag wrote: I dont know what you meant Paul by this, can you help me abit more?
As an aside you should probably put the max gap checking on, and tweak the max gaps to be large enough that it doesn't cause any problems.
Cheers
HondaDrag
Posts: 60
Joined: Wed Mar 06, 2013 5:12 pm

Re: Honda K series Crank & Cam Type

Post by HondaDrag »

Yes last time is was set to off, so will turn it back on and if any error comes up, tweak from there....great, good to know and also tommorow will check voltage at CDI and see from there.

Thanks alot for your help, Paul
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