Running a 20v st on cops

[joshyboy26]

Hi guys,

Referring back to this old thread, it never really got confirmed or denied.

http://forums.club4ag.com/zerothread?id=18900&page=22


Can i run a stock 20v silvertop with stock wiring and computer on 4cops off the igt wire?

I know you can on a blacktop however no one can conform or not on an st.

And if so, due to me running the motor in a suzuki sierra with no tacho can i unplug the coil and ignitor and throw them away? Or do i have to join some wires up to make the computer happy?

Thanks in advance

[aceforever]

As far as I can see blacktop is still running pointer type distributor with cam position sensors for ECU to time sparks. The output of ECU controls timing for the ignitor to fire, and the pointer in the distributor chooses the right cylinder to fire the spark. the 4AGE ECU only has one output wire. Modern ECUs have four wires (one per COP). There's another type called wasted-spark and basically fires an extra spark each time.

Here's a video that is similar to the setup we have on our motors.
https://www.youtube.com/watch?v=QYx8J_5l5wY

The number of teeth on the cam position sensor varies, but overall application is pretty much the same.

Without some aftermarket ECU that can read your trigger sensors correctly, it's most likely that you would fire all the COPs at once.

Not having the tachometer working doesn't mean the engine doesn't need spark. The point of a coil is to build up enough energy for the spark, and the ECU tells the ignitor to send that energy to the spark plugs. Unless you're using COP, you should definitely keep coil and ignitor.

[joshyboy26]

No thats right, thats what i want to do is fire all cops at the same time.

[aceforever]

I'm sorry but this is not something I'd recommend. You're going to ignite on completion of intake stroke.

[jondee86]

You're going to ignite on completion of intake stroke.

Logically you would expect that to happen, but due to some special kind
of white man's magic... it does not There are two possible explanations...
either the lack of compression and short spark duration of the COP is not
sufficient to light a fire. Or the engine is using sequential injection so there
may not be any fuel present at the end of the intake stroke ? Regardless,
the engine does run quite happily with batch firing of the COPs.

Cheers... jondee86

[aceforever]

Interesting. Hahaha "white man's magic"

I could see compression might be the cause. Or spark duration. That's good food for thought.

I'm thinking sequential injection should not matter as completion of intake stroke would always suck in a good air fuel mixture regardless of injection strategy for the engine to run.

[jondee86]

I know you can on a blacktop however no one can conform or not on an st.

There is no difference between the BT and ST OEM ignition system. What
works for one will work for the other. If you have 3-wire COPs you will need
to keep the factory coil and igniter to provide the IGf signal for the ECU.
If you have 4-wire COPs you can junk the coil and igniter.



This diagram shows how 4-wire COPs are wired when they are OEM fitted
to a vehicle and fired sequentially. You will trigger all four coils by feeding
them from the single ST ECU IGt output. If you have 4-wire COPs you just
need to take one IGf output back to the ECU. If you have 3-wire COPs there
will not be a IGf signal from the COP, so you need to keep the ST coil and
igniter.

Cheers... jondee86

[aceforever]

Just to satisfy my curiosity. What's the downside of running COPs this way? Is there any possibility of causing misfires?

EDIT: Found some people with the same conversation:

Original statement similar to mine:

This means firing at the bottom of the intake stroke. What keeps the charge from preigniting?

Replies to that:

Oddly enough, the idea for this came from someone with an AE86 w/ blacktop trying to convert to the 1ZZ coils. He had wired it up so that it did EXACTLY that. He said the thing runs, but not real well. I am a bit shocked that it works at all (for exactly that reason, you are effectively firing near TDC/BDC of every stroke).

I felt the same way when I heard it too meller.
As I understand it the 2 cylinders on BDC would not be effected much.

One would be on BDC in the power stroke so the spark event wouldn't do anything.

The other cylinder would be on BDC on the intake stroke with the cylinder filled with fuel/air mixture. Because the cylinder is on BDC and the charge has not yet been compressed the ignition event has little to no chance of igniting the mixture prematurely.

Like I said, It could work but it is dirtiest way of going to COP's

http://www.mr2oc.com/2-mki-84-89-na-sc/ ... -4age.html

[jondee86]

I'm thinking sequential injection should not matter as completion of intake stroke
would always suck in a good air fuel mixture regardless of injection strategy for the
engine to run.

My bad... I was thinking wasted spark where the "wasted" spark occurs at
the end of the exhaust stroke. So you are quite correct... because the COPs
are firing every 180 deg of crankshaft rotation, they will be firing at the end
of the intake stroke when there obviously will be fuel present (except for
direct injection engines).

The only downside to batch firing COPs that I have heard of, is the possibility
of the COP overheating due to firing at 4X its design rate, and shortening
its working life. This does not appear to be a major issue. It has also been
suggested that the COPs may have an issue with coil charging at high rpm
due to the rapid cycling with batch firing. But again, this does not seem to
be a problem in the real world.

Cheers... jondee86

[yoshimitsuspeed]

Most people experience idle issues with the batch fire setup. It seems as though higher RPMs change the relationship enough to not ignite the intake stroke.
With that said, personally I would not run batch fire COP. It can cause idle and low RPM issues and definitely runs the COPs well outside their design parameters.
We are very close to completing our sequential fire COP module that works with the stock ECU. It has been a much longer road than we originally intended but the electrical engineer on the project has now successfully had it running both an NA 16v and a GZE 16v. Electronically the GZE is the same as the 20 valves which means this module will work with them as well as a number of other similar era motors like 5S, 3S etc.
Right now we are in the process of getting the boards produced.

[joshyboy26]

Thanks for the replies guys cool! That makes me happy.

As this is my 4wd weekend car im not too fussed on shorter cop life because im just not going to drive it enough.

Can anyone suggest a 4wire cop to use?

What is the realistic timeframe til i could have one of those controllers in my hand and an expected cost??

[jondee86]

Read here... http://www.sq-engineering.com/tech-arti ... info-guide

Cheers... jondee86

[yoshimitsuspeed]

Thanks for the replies guys cool! That makes me happy.

As this is my 4wd weekend car im not too fussed on shorter cop life because im just not going to drive it enough.

Can anyone suggest a 4wire cop to use?

What is the realistic timeframe til i could have one of those controllers in my hand and an expected cost??

I would love to say two months and around $100 but both figures are still a little up in the air.

[aceforever]

Most people experience idle issues with the batch fire setup. It seems as though higher RPMs change the relationship enough to not ignite the intake stroke.

So I guess you just have to idle higher? Or do the COP properly hahaha.

[ae86cesar]

Why would you want to run coilpack this way? Have you considered standalone ecu? I used to run wasted spark coilpacks on megasquirt 3 and when I got the expansion board and ran full sequential there was a notable difference from my experience. And you will have the option to tune for future upgrades.

Sent from my SM-N910T3 using Tapatalk

[Deuce Cam]

^I guess it's an appealing work-around for the dizzy clearance problems when used in a rwd platform, and still being able to use the oem ecu. Plus cop's are swanky.

On the old club4ag thread there were folks who who having trouble with engine drivability at high rpm, also arcing issues with the igniter since a lead wire no longer runs to the dizzy, iirc. It's been a while now though so I wouldn't be surprised if clever individuals have worked around the problems. Jondee86's post seems to indicate that a 4 wire cop would solve the oem igniter issue since it's no longer needed.