MS Extra on a Honda, trigger angle problems and solutions

mega_user · Post by **mega_user** » Mon Jul 18, 2005 3:53 pm

It is one od the latest Honda cars . OBD2b equipped. It think it is probably one of the very rare VTEC Hondas running full MS Extra. The car has fixed base ignition timing. The distributor can not be rotated and there are no timing marks on the crank pulley. So we assumed what the trigger angle should be. We assumed wrong. It turns out it must be 1 degree.

The tip of the VR sensor type wheel (two tips on the crank) goes past the VR sensor 10 degree before TDC.
We had to set the cranking timing to 1 (basically zero advance) so the timing in not to much advanced when cranking. But it is still to much advanced

It is possible to specify a trigger angle of 190 degree? Or a negative trigger angle? The car now runs 60 degre of timing at 100 kpa and 4000 rpm to get the timing right.

Post by **jsmcortina** » Mon Jul 18, 2005 4:29 pm

Just specify 10 as that is the trigger angle.

EDIT. Re- reading the post I am a little confused. Why must the trigger angle be 1 degree when the VR sensor aligns with the trigger at 10deg ?

James

mega_user · Post by **mega_user** » Mon Jul 18, 2005 5:24 pm

I need some guidance here.
It seems that a 10 degree the trigger angle is to advanced. It shold be (minus) -10 degree. Maybe I am the one that is confused here.

For example , the cranking timing that was fixed at 10 degree was way too advanced. The engine was detonating when cranking. When we set the timing cranking at 1 degree it was much better. If it would go back another 5 degree maybe it would be even better.

The fact is, with 1 degree trigger angle the maximum timing is at 60 degree advanced and I have the trim angle (just remembered) set at 10 degree. Would moving the trigger angle to 10 degree move the timing in the spark table back to 50 degree maximum?

The timing is right on spot now, 10 degree less and the engine loses a lot of power.

Please have patience with me, the d*** engine is pretty rare. All other Hondas have the VR sensors in the distibutor, this one has them on the crank. And no timing marks to check the timing.

mega_user · Post by **mega_user** » Mon Jul 18, 2005 5:29 pm

Another thing I just remembered. We are using a 4 pin HEi module to condtion the VR signal. What if the two wires from the VR sensor are reversed? What happens in this case?
What if we reverse them just to test it?

whittlebeast · Post by **whittlebeast** » Mon Jul 18, 2005 7:36 pm

Most new Hondas have a tach lead that is not connected to anything. As I remember it is a square wave. In a RSX-S it is a blue wire right near the battery. I have no idea if it would be of any value to you.

Andy

mega_user · Post by **mega_user** » Tue Jul 19, 2005 2:54 am

It is a late model Prelude. Still Honda old school VTEC engines

But pretty new OBD2b electronics from factory.

dieselgeek · Post by **dieselgeek** » Tue Jul 19, 2005 8:10 am

You definitely want the VR signal wires to have correct polarity... and maybe try using an HEI 7-pin instead of a 4-pin, since the 7-pin has a true VR conditioning circuit installed...

mega_user · Post by **mega_user** » Tue Jul 19, 2005 9:54 am

How can I know when the polarity is right and what are the simptoms of wrong polarity? I'm still not sure we got it right.

With two teeth rotor on the crankshaft the 4 pin HEI works excellent. We even used normal unshielded wires. Only the Dave cap is installed and tach readings are OK.

I would also appreciate a little help on the subject of the trigger angle.
How does it affect the igniton advance table if trigger angle is moved from 1 to 11 degree. Will the ignition table be advanced or retarded for those 10 degree?

I saw your thread on the other MS-ed Honda. Great work.
This one is a little more difficult - no sensors in the disty, only on the crank.
Could the 7 pin HEI decode the 24 (48 in the disty) teeth? Removing one tooth would result in a 24-1 wheel and the wheel decoder could be put to work. Wasted spark or COP would be interesting to try.

dieselgeek · Post by **dieselgeek** » Tue Jul 19, 2005 10:18 am

mega_user wrote:How can I know when the polarity is right and what are the simptoms of wrong polarity? I'm still not sure we got it right.

With two teeth rotor on the crankshaft the 4 pin HEI works excellent. We even used normal unshielded wires. Only the Dave cap is installed and tach readings are OK.

I would also appreciate a little help on the subject of the trigger angle.
How does it affect the igniton advance table if trigger angle is moved from 1 to 11 degree. Will the ignition table be advanced or retarded for those 10 degree?

I saw your thread on the other MS-ed Honda. Great work.
This one is a little more difficult - no sensors in the disty, only on the crank.
Could the 7 pin HEI decode the 24 (48 in the disty) teeth? Removing one tooth would result in a 24-1 wheel and the wheel decoder could be put to work. Wasted spark or COP would be interesting to try.

I can answer some of these questions:

THe polarity on a VR sensor is correct when the AC voltage goes UP before it goes DOWN - by viewing this on an oscilloscope. There IS a way to check without a scope, by using a cheaper VOM - since I had a scope, I skipped that method... but basically, the HEI module is triggered when the voltage crosses "zero" but you want the polarity correct - our HEI 7-pin did NOT like having polarity reversed, we got all kinds of weirdness with timing that I never could explain, but went away once we got polarity correct (there are guys on this board that can explain WAAAY better than me!!).

Increasing trigger angle should have the effect of ADVANCING your timing but I am also confused on the trigger angle, as i have read that you cannot have more advance than trigger angle - your motor is going to want to idle around 20+ degrees of timing, so I hope a smarter guy gets on and clarifies for both of us... in our case, 60 degrees trigger angle resulted in timing that matched what MS was commanding - so we called it "good" and left it at that.

I believe 24 teeth at 7000RPM would be 2800 teeth per second (Hz), I'm not sure what the upper limit is on a 7-pin HEI (do a search, lots of posts about this). I myself am just getting an understanding of VR sensors and the HEI modules, sorry not too much help here...

mega_user · Post by **mega_user** » Tue Jul 19, 2005 11:00 am

The trigger angle is an interesting topic. At the moment the MS runs on a 1 degree trigger angled. Which I think is not OK. Since cranking timing must be set to 1 degree otherwise the engine detonates really bad and most of the time will not start. But once it starts the timing seem to be way to much retarded.
10 degree advanced on the ignition map is way different from 10 degree when cranking.

At the same time with 1 degree of trigger angle I can modify the ignition timing map between 10 and 60 degree and the engine responds to those changes. This is not what the instructions for MS say.

Someone with more insight on the inner workings of the MS could help here

Post by **jsmcortina** » Tue Jul 19, 2005 11:16 am

By specifying a trigger angle like 1 or 10 deg you imply a "next-cylinder" operation mode.
During cranking the code will fire as soon as it gets the trigger.

Above cranking in run mode for greater advance, say 20 deg, the code will wait until the next cylinder to fire.

Say you specified 1deg trigger and have commanded 20BTDC advance, then you want the spark 19deg before the trigger, so the code will wait 180-19 = 161deg after the trigger.
Say you specified 10deg trigger and have commanded 20BTDC advance, then you want the spark 10deg before the trigger, so the code will wait 180-10 = 170deg after the trigger.

Now, in your case if you think the physical trigger is 10BTDC, but you have specified 1BTDC, what now?
With a commanded 20BTDC the code is going to wait 161deg but this will be 9deg more advanced than you want because the trigger comes earlier than you told the MS.

Are you using dwell? What are your settings?

James

Post by **jsmcortina** » Tue Jul 19, 2005 11:17 am

One more thing. If you haven't already you REALLY need to add some timing marks. Even rough chalk marks have got to help understand what is happening.

James

mega_user · Post by **mega_user** » Tue Jul 19, 2005 1:20 pm

Thanks for clearing out how trigger angle works with MS.

Yes, we made a timing mark after everything else failed and this way we found out that 1 degree of trigger angle and 10 degree in the ignition settings is just a few degree apart from the 10 degree timing mark on the pulley.

This way the car runs , but the cranking timing must be set to 1 degree, maybe "negative" degrees would make for an even better cranking.
And we left the trim angle at 7 degree. Does trim angle influence the cranking timing number?

Also the entire ignition table is 10 or more degree more advanced as it should be.

We use a MSD6A with a blaster coil for igniting the spark. The dwell is set to fixed duty, 75% duty cycle.

Otherwise the engine runs strong, now we must just find the right trigger angle.

dieselgeek · Post by **dieselgeek** » Tue Jul 19, 2005 1:26 pm

mega_user wrote:Thanks for clearing out how trigger angle works with MS.We use a MSD6A with a blaster coil for igniting the spark. The dwell is set to fixed duty, 75% duty cycle.

Otherwise the engine runs strong, now we must just find the right trigger angle.

Did you select "spark output inverted = yes" ? this might have something to do with the confused timing...

Thanks James for the clarification on trigger angle and This Cyl / Next Cyl - that's the best explanation I've read and helped a lot!!

FOr the timing, what I suggest doing is - once you have the motor idling - select "fixed angle" of 20 degrees (this is base on most Honda's, no?), then adjust your Trigger Angle until the timing light shows exactly 20 degrees on the crank pulley. That will help you find the right trigger angle,

-scott

Post by **jsmcortina** » Tue Jul 19, 2005 1:41 pm

A trim angle of 7 deg will advance the whole table by 7deg. It is only intended for quick tuning testing. Normally it should be zero.
Try putting it back to zero and setting your trigger angle to 10deg.

James

mega_user · Post by **mega_user** » Tue Jul 19, 2005 2:20 pm

Does the trim angle also advance the cranking timing? Just for the record.

I noticed the trim angle can not be set to a negative number. If someone wants to retard the whole table , all the numbers in the table must be modified.

Spark output is set to inverted. I have the MS pretty much sorted out on most things.
The trigger angle was giving us headaches with the Honda.

It is difficult to get the exact timing to the last degree, since there are no timing marks from the factory. It also has s fixed distributor that can not be rotated.

In a day or two we will tune the car again (hopefully on a dyno) and I will report back how it went. Base timing on the Hondas is 16 degree I think.

Thanks for all the useful suggestions. Doing a full MS install on a Honda is pretty rare. All other use the Hondata and similar ROM editors.

Post by **jsmcortina** » Tue Jul 19, 2005 2:32 pm

Negative Trim ought to be allowed. We'll get it fixed some time. Keep us posted on your progress.

James

mega_user · Post by **mega_user** » Wed Jul 20, 2005 10:52 am

Allowing for a negative trim would help a lot.
But does the trim angle also advance or retard the cranking timing? Or just the ignition table.

Rodney Sparks · Post by **Rodney Sparks** » Wed Jul 19, 2006 7:02 am

When setting up MSnSE for a Honda distributor, could you just move the spark plug wires forward one cylinder on the distributor so you start out with 90 degrees of advance? I don't remember exactly how a Honda distributor is bolted to the engine, but I recall that you can't really grab the distributor and advance it 60 degrees like you can on many cars.

I have a customer who wants to install an MS on a D16A6 race car, and I'm trying to help him through it. I know that one other option is to knock one tooth off of his 24-tooth wheel, but it'd be nice to leave the wheels intact...

Thanks!

-Rodney