Ignition Mods & MPG

[Ronin8002]

Subscribing. I've got the original msd dis4 that I bought years ago when I had my supercharged OHV and might try installing it on my 2004

 

[snoranger]

Subscribing. I've got the original msd dis4 that I bought years ago when I had my supercharged OHV and might try installing it on my 2004

Get a good baseline of your MPG for a month or 2. Then track it after the install and report back here. I'd like to see if you get similar results as me.

 

[2000StreetRod]

Still need plug wires

Do you still need the plug wires?

Yes, especially if I build a table top system for evaluation.

Yes, the coil packs should be the same. Ford only used 2 different style 6cyl coil packs... The only difference between them was the angle the connector attached at. (They use the same connector.)

The photo showed the horizontal connector.

I may a 36-1 wheel and crank sensor around, if you want to do it mechanically.

I could have purchased a 36-1 wheel and VR sensor for another $25 but I only had 5 minutes to think about it before the auction closed. I guess I could find a way to mount the trigger wheel on an electric motor shaft, the motor in a box, and the reluctor the correct distance from the wheel. I've read that the rpm should be at least 400 for reliable operation. I just remembered I need a new variable speed drill. I think my old one can be locked on at user settable speeds.

 

[2000StreetRod]

Possible Dual Coilpack Design

Below is a block diagram of a possible dual coilpack design that increases the spark energy of each combustion plug while avoiding the issues with combining the high voltage outputs of each coilpack. The design incorporates Insulated Gate Bipolar Transistors (IGBTs) triggerred by the PCM to control the current flow thru the coilpack primaries.

In the stock waste spark system illustrated in a previous post the output voltage required to fire the plug on the compression stroke is dependent on the gaps and pressures between the gaps of the paired spark plugs. The gaps for both plugs are the same but the chamber pressure of the compression plug is much greater than that of the exhaust stroke plug. Ford justifies the waste spark design by arguing that the voltage required to fire the exhaust stroke plug is much less. If the voltage required is directly proportional to pressure then the exhaust stroke plug may require 3,500 volts while the compression stroke plug may require 35,000 volts (static compression ratio of the SOHC V6 is 9.7:1). For a series circuit the current is constant thruout the circuit. Power = voltage * current so for this example one tenth of the power is wasted. The circuit above eliminates the voltage (and power) associated with the exhaust stroke plug when the compression stroke plug is firing. Assuming the power in the coil primaries remain the same as for the stock configuration, the spark power will increase by 10%. It may be possible (by using high current IGBTs) to increase the power in the coil primaries.

By determining (experimentally) the phase relationship of the primary to the secondary windings it is possible to achieve current flow in the same direction for all spark plugs. At this time the (+) shown on the windings is purely speculation.

One disadvantage of using the IGBTs is their added switching delay which impacts the timing of the spark initiation. Fast IGBTs are available with turn off delays (when the primary coil field collapses) of 100 nanoseconds (0.1 usec). For my stock rev limit:

6250 revs/min *1 min/60 secs *360 deg/rev * 0.1 usec = 3.75 degrees

This delay is not major but may be enough that retiming might be needed for optimum performance. Retiming can be accomplished with the SCT Pro Racer software package.

 

[2000StreetRod]

Ignition system power requirements

Fuse 19 (25 amps) in the Central Junction Box provides ignition switch battery voltage to the PCM Power Diode, PATS, the radio noise capacitor and the ignition coilpack. The PATS signal is just to notify it that the ignition is on. It should be very low current. The radio noise capacitor current requirements can be ignored. The voltage to the PCM Power Diode is used to energize the PCM power relay and should be less than 1 amp. Fuse 19 is 25 amps for either the V8 (four coils) and the V6 (three coils). I suspect the current draw for the V6 coilpack is 10 to 15 amps.

The coil primary resistance is typically 0.5 ohms. If the entire battery voltage were dropped across the primary of one coil the current would be:
(I = E/R) I = 12 volts/0.5 ohms = 24 amps
Since all three coil primaries are simultaneously energized for most of the time it is obvious that the PCM internal circuitry limits the primary current flow. Fast switching IGBTs with 20 or 30 amp control capacity are readily available. It may be possible to double the current flow thru the primaries to achieve a higher power spark. However, care must be taken to ensure the primary windings do not overheat and fail.

 

[toyotaspeed90]

Below is a block diagram of a possible dual coilpack design that increases the spark energy of each combustion plug while avoiding the issues with combining the high voltage outputs of each coilpack. The design incorporates Insulated Gate Bipolar Transistors (IGBTs) triggerred by the PCM to control the current flow thru the coilpack primaries.
View attachment 68772
In the stock waste spark system illustrated in a previous post the output voltage required to fire the plug on the compression stroke is dependent on the gaps and pressures between the gaps of the paired spark plugs. The gaps for both plugs are the same but the chamber pressure of the compression plug is much greater than that of the exhaust stroke plug. Ford justifies the waste spark design by arguing that the voltage required to fire the exhaust stroke plug is much less. If the voltage required is directly proportional to pressure then the exhaust stroke plug may require 3,500 volts while the compression stroke plug may require 35,000 volts (static compression ratio of the SOHC V6 is 9.7:1). For a series circuit the current is constant thruout the circuit. Power = voltage * current so for this example one tenth of the power is wasted. The circuit above eliminates the voltage (and power) associated with the exhaust stroke plug when the compression stroke plug is firing. Assuming the power in the coil primaries remain the same as for the stock configuration, the spark power will increase by 10%. It may be possible (by using high current IGBTs) to increase the power in the coil primaries.

By determining (experimentally) the phase relationship of the primary to the secondary windings it is possible to achieve current flow in the same direction for all spark plugs. At this time the (+) shown on the windings is purely speculation.

One disadvantage of using the IGBTs is their added switching delay which impacts the timing of the spark initiation. Fast IGBTs are available with turn off delays (when the primary coil field collapses) of 100 nanoseconds (0.1 usec). For my stock rev limit:

6250 revs/min *1 min/60 secs *360 deg/rev * 0.1 usec = 3.75 degrees

This delay is not major but may be enough that retiming might be needed for optimum performance. Retiming can be accomplished with the SCT Pro Racer software package.

This scenario seems to be basically building a COP style setup (without the actual coil on the plug.... but essentially one coil winding per cylinder).

I don't fully understand the purpose of trying to run dual coilpacks to fire one plug twice theory. Nissan ran 8 plug 4 cylinders in the late 80's due to emissions purposes but it's been reported that it had essentially no effect on the gas mileage.

I know that in the Escorts there were 2 variants of the EDIS4 units... red vs. blue sticker units (don't know exact part number) and that it's rumored the blue (less common) had multiple spark discharge setup at idle speeds to help. I would think that Ford would include this especially on larger engine'd vehicles if it was something that would help marketing (and SUV's/gas mileage is a marketing point) but it doesn't appear it was.

Also, for those that aren't aware, the Ford EDIS system is quite adaptable - I've used them (as have thousands of others) when building a standalone Megasquirt system for MR2's and currently one of my Corolla's.

From parts store exprience the only issue I recall from the specific Ford EDIS systems is that they required a double platinum plug (plat. on the electrode as well, NOT a dual electrode plug) as the wastespark design on these actualyl caused issues with standard platinum and copper core plugs after a few thousand miles.

If you really wanted to improve the mileage of the vehicle you'd be better off watching tire pressures, making sure your O2's are reading correctly, no exhaust leaks, running the lowest octane fuel w/o pinging, and then working on drag the vehicle has & areas that can be improved on the exterior (for example wheel covers).

My opinion is just that... and I'm new to this forum so it probably will be glossed over... but just thought I'd throw my 2 cents out.

 

[2000StreetRod]

COP ignition system

This scenario seems to be basically building a COP style setup (without the actual coil on the plug.... but essentially one coil winding per cylinder).

Thank you for your comments! I wasn't familiar with the coil on plug ignition system so I did a quick internet search and agree that my possible dual coilpack design previously posted is very similar. The main difference is that in a COP system there is a PCM trigger output for each plug.

I don't fully understand the purpose of trying to run dual coilpacks to fire one plug twice theory. Nissan ran 8 plug 4 cylinders in the late 80's due to emissions purposes but it's been reported that it had essentially no effect on the gas mileage.

An idiosyncrasy of a closed loop fuel control system using O2 sensors is that more complete combustion reduces O2 levels. The PCM thinks the air/fuel mixture is lean and richens it to compensate. My Bosch Fuel Injection & Engine Management book states that best fuel economy is achieved at lambda = 1.05 (15.4:1) but due to current three-way catalytic converter design the NOx emissions rapidily increase above lambda =1 (14.7:1).

I know that in the Escorts there were 2 variants of the EDIS4 units... red vs. blue sticker units (don't know exact part number) and that it's rumored the blue (less common) had multiple spark discharge setup at idle speeds to help. I would think that Ford would include this especially on larger engine'd vehicles if it was something that would help marketing (and SUV's/gas mileage is a marketing point) but it doesn't appear it was.

Ford claims going to COP ignition for reliability and reduced weight:Coil-on-Plug Ignition

. . . If you really wanted to improve the mileage of the vehicle you'd be better off watching tire pressures, making sure your O2's are reading correctly, no exhaust leaks, running the lowest octane fuel w/o pinging, and then working on drag the vehicle has & areas that can be improved on the exterior (for example wheel covers). . .

Good points and I plan to do some of those. However, I enjoy experimenting.

 

[2000StreetRod]

EDIS 6 package

Yesterday I received the package containing an EDIS 6 module, coilpack, and associated connectors with pigtails. As snoranger posted, the coilpack was identical to the others I have (made in Spain).

I'm now working on the dual fire design which may be what I select to implement (more complex mechanically but greater spark power than the others).

I need ignition wires to modify. If anyone has an old broken set I'll pay the shipping cost. I need the OEM style with the right angle connector at the coil. There's no room for the straight coil connectors. I can't find inexpensive used wire sets on eBay.

 

[snoranger]

Hey Dale, I dug up some wires for you. What else do you need?

 

[2000StreetRod]

36-1 wheel & reluctor?

Hey Dale, I dug up some wires for you. What else do you need?

You mentioned that you might have a 36-1 tooth trigger wheel. I found one on eBay Universal 36-1 variable reluctor/trigger wheel for about $15. It is only 5 inches in diameter but has a 1/4 inch dia. hole which makes mounting on an electric motor easier. If you have a variable reluctor that would be helpful.

 

[Ronin8002]

Get a good baseline of your MPG for a month or 2. Then track it after the install and report back here. I'd like to see if you get similar results as me.

I may not install it as I don't have the RPM adapters to make it work. The most I did with it was put the box in my old truck to mock up fitment, but never wired it in. So basically its unused. Probably will end up selling it.

 

[snoranger]

You mentioned that you might have a 36-1 tooth trigger wheel. I found one on eBay Universal 36-1 variable reluctor/trigger wheel for about $15. It is only 5 inches in diameter but has a 1/4 inch dia. hole which makes mounting on an electric motor easier. If you have a variable reluctor that would be helpful.

I'd get the wheel off Ebay if I were you. If I do have one, its off a balancer and will have a 4" (?) hole in it.
I'll send you a crank sensor or 2 with pigtails.

 

[toyotaspeed90]

Any Ford with an EDIS unit will have a 36-1 wheel. Usually these are taken from Ford Escorts as they're pretty easy to get off the vehicle and then the wheel is only pressed onto the crank pulley (little heat and a tap of a hammer - they fall off). They're easy to find at junkyards and if you get the wheel off in the yard they probably won't charge you much.

If you really like to experiment you might want to consider going with an aftermarket unit like Megasquirt.

My 87 MR2 had a Japanese supercharged engine (higher compression, higher boost, reconfigured head) that I was running on Megasquirt. I was able to turn the s/c off (uses an electromagnetic clutch, similar to an a/c pump) and tune the MS for those MAP ranges. SC on I could tune much more aggressively. I was able to yield all of 14mpg with the s/c on but a surprising 45mpg with it off (note: a stock first gen MR2 N/A will be at about 30-32mpg for highway driving).

 

[2000StreetRod]

Megasquirt

Any Ford with an EDIS unit will have a 36-1 wheel. Usually these are taken from Ford Escorts as they're pretty easy to get off the vehicle and then the wheel is only pressed onto the crank pulley (little heat and a tap of a hammer - they fall off). They're easy to find at junkyards and if you get the wheel off in the yard they probably won't charge you much.

I only need the 36-1 wheel for table top prototyping.

If you really like to experiment you might want to consider going with an aftermarket unit like Megasquirt.

I agree that a Megasquirt system is for experimenters and possibly appropriate for single use vehicles (dragsters, circle track racers, etc.): MegaSquirt systems?

My 87 MR2 had a Japanese supercharged engine (higher compression, higher boost, reconfigured head) that I was running on Megasquirt. I was able to turn the s/c off (uses an electromagnetic clutch, similar to an a/c pump) and tune the MS for those MAP ranges. SC on I could tune much more aggressively. I was able to yield all of 14mpg with the s/c on but a surprising 45mpg with it off (note: a stock first gen MR2 N/A will be at about 30-32mpg for highway driving).

Very interesting. Did you have a centrifugal supercharger? Was there a supercharger bypass for when the electromagnetic clutch was disengaged? Does Megasquirt allow real time switching between two sets of air/fuel ratio and ignition advance tables?

 

[2000StreetRod]

Purchased the trigger wheel

I'd get the wheel off Ebay if I were you. If I do have one, its off a balancer and will have a 4" (?) hole in it.
I'll send you a crank sensor or 2 with pigtails.

Thanks. I purchased the 36-1 trigger wheel. Looking forward to receiving your items. You've been a great help with both of my recent projects!

 

[snoranger]

Thanks. I purchased the 36-1 trigger wheel. Looking forward to receiving your items. You've been a great help with both of my recent projects!

I've got 2 crank sensors (and pigtails) and at least 9 wires. I'll try to get it shipped out tomorrow.

 

[toyotaspeed90]

I only need the 36-1 wheel for table top prototyping.



I agree that a Megasquirt system is for experimenters and possibly appropriate for single use vehicles (dragsters, circle track racers, etc.): MegaSquirt systems?



Very interesting. Did you have a centrifugal supercharger? Was there a supercharger bypass for when the electromagnetic clutch was disengaged? Does Megasquirt allow real time switching between two sets of air/fuel ratio and ignition advance tables?

Actually MS is more than appropriate to be used for daily drivers or the weekend warriors (off road, racing, etc).

MS isn't capable of switching between maps (well, at least not what I had... I built that car in like 2004'ish when MS was still really brand new... I'm talking 8x8 resolution maps) however the map reading between when the SC was on and not on was so different you could tune the map separately. The map was based on vacuum/boost (manifold pressure) and RPM's... There are also acceleration step values where you can change the additional pulsewidth percentage based on TPS value... IE if you're barely on the gas then add very little.... if you're really on it, add more fuel.

There is a factory bypass on those supercharger setups.... the toyota SC12 is very similar to an M62 (in size) but from factory has the electo-magnetic clutch.

 

[2000StreetRod]

Dual Fire Design

Below is a diagram of a dual fire ignition system.

It's advantages are:
Twice the spark power of the stock waste spark system
Stock timing retained for the first spark. [The start of the second spark will be delayed from the start of the first spark by the IGBT turn off switching time. The MSD DIS-4 Plus fires multiple sparks for 20 degrees of crankshaft rotation at low to mid engine speeds. An IGBT turn off delay of 400 ns represents 15 degrees at the rev limit (6250 rpm).]

It's disadvantages are:
Current flows in opposite directions on paired spark plugs (like stock)
Wastes energy firing the waste plug (like stock)
Increases PCM trigger current by IGBT gate current

Some issues to resolve:
Interaction of secondary windings with no isolation diodes
Method to splice together two spark plug wires

I've decided to pursue this approach since it potentially can generate a much larger spark power than the dual pack design and will not require purchasing the Pro Racer software package to alter ignition timing.

 

[2000StreetRod]

exhaust fan motor

I purchased a 1/100 hp, 3,000 rpm, 115 vac exhaust fan motor via eBay to drive the 36-1 trigger wheel. I could have used a lower power motor but this was the cheapest one I could find with a 1/4 dia and long (2 in) shaft to mate with the trigger wheel. Next I need to figure out how to mount the motor, trigger wheel and variable reluctor.

 

[2000StreetRod]

Inverters

All of the IGBTs I've researched to date are turned on (collector to emitter current flows) when the input voltage (gate to emitter) exceeds a specified value and is turned off (no output current) when below a specified voltage. Unfortunately, the trigger output of the PCM is normally low (allowing current flow thru the coil primary) and pulses high (breaking current flow inducing a voltage in the coil secondary) to fire the spark plug. Therefore, an inverter is needed between the PCM trigger and the IGBTs in order for the second coilpack to function normally. The diagram shows the added inverters.

An NPN transistor with a base input resistor and collector load resistor may comprise a suitable inverter circuit.

The transistor switching delay will have to be carefully selected.