How much dwell time for Ford COP ignition? Anyone have scope photos or data from factory manuals?

 

making it more complicated than it actually is , what are you trying to do - tell if a cop is bad? u need a back scatter history reading 1-8 thats how you tell. I haven't hered of another way - they don' just go bad , they wait until u least expect it , then freak the nasty on yuh..

 

From what I've read, when one goes the rest follow.
If you think you have one bad coil better start looking to replace them all.

 

Wasn't DWELL time the amount of degrees the points were closed on the old style points and condensor ignitions?
How could DWELL time be measured on these computer controlled vehicles?

 

That's what I was wondering!

 

I was hoping that someone had a manual showing it.

 

John, it's not quite as easy as you are thinking to see/ understand dwell time and how it is arrived at.
The early 5L TFI was known as a push start system. This name is given due to the ability of the TFI to increase dwell of a slow turning engine for either cranking or push starting the vehicle.
About 1990 some TFIs was changed to allow for computer (EEC) controlled dwell timing.
The difference between these are in their color so they can be told apart otherwise they look identical. If they are swapped an IDM fault could be triggered.
When it comes to the 4.6/5.4 the DIS, EDIS and later systems ignition dwell time is fully calculated by the PCM as a moving variable so becomes difficult to discribe.
Info can be found in C. Probst book on FI, pages 122 to 126 for a start but does not include a COP system.
When looking at this with a scope the IDM signal relationship to the SPOUT/SAW signal should show the dwell time area.
You see it is an involved process with the right equipment to be able to see this.

 

Bluegrass:

Are any of the Ford COP systems waste spark? I read on another forum that some 5.4L EEC-V's only have four ignition drivers. If that is true, do you know the primary resistance of the coils used in that application? I think trying to drive two of the 0.4 ohm coils with one driver would be risky, unless they were wired in series.

 

With one coil per cylinder, the system is not a wasted spark type.

A waste spark is one coil per two cylinders. A controller determins when the right time is to fire the cylinder under compression. The other cylinder it is paired with also fires but during it's exhaust cycle when nothing will happen. In some later systems the PCM drives the coils directly and does not use a seperate controller.
One driver per coil that fires two plugs.

It is the same thing as a single cylinder engine that gets it's ignition action from a flywheel magnet and coil assembly (magneto). The coil fires the plug everytime the flywheel passes the coil on all other cycles other than just the compression power cycle.
Those earlier engines that used coil paks and plug wires (no distributer) are the wasted spark type systems both 6 and 8 cylinders.
Some other variations of this system are dual plug DIS and dual plug inhibit and even mutiple spark used on other small engines in the Ford line up.
In wasted spark systems the type of plug used has a large effect on how long they last in service due to the effects the spark has on the electrodes from the reversed polarity fireing during one of a pair operation.
Could we ask why the interest in this operation to this level, not that it hurts any to know but curious.

 

Thank you for your reply. I doubted the info on the other forum.

Not to argue, though, but coil on plug does not exclude waste spark. If the drivers were stout enough, a system could be designed to run two coils per channel with COP, and there would be no reverse firing plugs.

Some aftermarket ECU's convert COP systems to waste spark, but those systems use so called "smart coils", with built in ignition transistors, which are easy to drive. For example, the AEM ECU has five ignition outputs, so six, eight, and ten cylinder operation must be set up for waste spark.

 

Finally got around to measuring the dwell time. At idle, the EEC fires the plugs three times. Dwell on the first spark event is about 1.8 msec, and about 1.0 msec on the next two.

I bought a Pep Boys coil to play with. The coil current reaches 6 amps in 1.8 msec, when powered from a 14v supply.

 

To be specific, I was trying to get a feel for the minimum heat sink area for a surface mount IGBT.

I emailed you my results the other day. Did you get a chance to look at them?

 

Yes I did get mail from you.
Looked it over and with the info provided you got a good idea and I understand in principal what is happening with the "hang (on) time".
Have you tested on Ford Mod motors and saw any PCM codes from it's application?
Reason I ask is the PCM looks at a lot of circuits full time for opens, shorts and out of range circuit conditions.
Another question is what happens to the PCM timing when the knock sensor detects and retards the timing in addition to your dwell controller?
I could have used this on our sprint car last season because the heads are fast burn and don't need a lot of ignition timing before detonation sets in even on Alky fuel.
Just wondering about some of these things because the MOD motors are quite different than Carbed or earlier pre PCM controlled engines.
Most FORD car applications before the MOD motors don't use knock sensors except the trucks.
I would think a lot of testing over many applications and models has to be done to get a handle on all this.

Now you can design a torque converter man/auto lock that will trip off at RPM between 800 and 1000 so the converter dosn't stay locked up by brain fade and tripped off by brake application as a secondary backup. Should be easy to do.
I have an idea on how to do it with a simple relay and a pulseing supply related to the engine RPM.
Thanks for the report.

 

No mod motors yet, but many Foci using an earlier two channel version, since late '04. No reports of PCM codes or timing conflicts from users or SCT tuners.

I forgot to mention in the info I sent you that, as a side benefit, the spark energy increases when retarding.

 

Hello John,
Yes the dwell time increases the coil saturation time up to a point.
There is a way to get huge gains in spark energy at the plug tip but so far it is an aftermarket offering such as you may be headed for.
The plugs center resistance is one area that is a necessary evil presently for normal engine use but not needed for hi performance.
It holds down RFI back to the PCM as well as other circuits.
The real gains at this point are in CAP SYNCING energy right at the plug top.
There is an SAE paper discribing the whole process in detail.
A co. in the southwest has perfected the hardware , done the fleet testing and offers the kit to the public butyou have to search for it. No hi energy coils are used.
I remember the first time I built a CDI system back in 1973 and put it on a stock Ford ignition cables and dist.
I had spark all over the engine bay from it being to hot for the hardware.
Good luck with your design.