Differences in DIS modules?

007_SuperCoupe

Registered User
I'm curious if anyone knows what the specific differences are between an '89-'90 DIS module and the '91-'93 DIS module. They are different part numbers and significantly different in price.

Here's the break down: (I got the prices from rockauto)
Year Manufacturer Part # Cost
'89-'90 Airtex 6H1100 $102.79
'89-'90 ACDelco F1959 $110.79

'91-'93 Airtex 6H1101 $195.79
'91-'93 Motorcraft DY958 $222.79
'91-'93 ACDelco F1962 $249.79

They are different part numbers and as you can see, vastly different on price as well. I was always under the impression that they were all the same and thus interchangeable. Is that the case? Or is that why some people seem to have a continuous issue with their DIS modules...unknowingly installing the one for the wrong year.

Can anyone shed some light on what specifically is different between the different part numbers? I'm very curious to know. Thanks.
 
They are effectively interchangable. If there is any difference, it hasn't shown up as a specific issue. I've had a DIS from a 90 running on my 93 in the past with no problem. A 93 dis running on a 90 in the past with no problem.

that doesn't mean there isn't a difference. But it may be the difference isn't significant. I'd guess the older number is cheaper because it's much more common.
 
I'm not so convinced that it's not a factor into the premature failure of the DIS. I could see the possibility that some revisions were made to the design for '91, but then you would think that it would replace the earlier part and have that earlier part # be obsolete. But since that didn't happen and they are in fact still manufactured that way, that there had to be a significant enough difference that it would come into play.

I think that they may work, but with a long enough run on the engine, they would fail prematurely if installed on the wrong year SC. It's just a thought, but I'd like a little more technical information if anyone has it.
 
http://www.sccoa.com/forums/showthread.php?t=90420

I have been assured that since Standard started making all of the DIS Modules a few years back (remember the DIS Module "shortage") that the early version electrically is the same as the later model.

One possible difference is that in 91 Ford changed the Shop Manual so that heat sink grease was no longer the specified mounting substance so perhaps they no longer ground the module through the case AND mounting bolts. However I still use heat sink grease and will continue to do so since the module needs a way to pass its heat away from the module to protect the semiconductor devices inside the module.
 
>the module needs a way to pass its heat away from the module to protect the semiconductor devices inside the module.

I checked a 1990 SC engine at operating temp and found the pedestal at 175 deg. F, and the module (mounted on 1/16" X 5/16" dia. spacers) at 135 deg. F.

Given that heat rises, I seriously doubt that there was any design consideration for a dedicated heat path from the module, down into the pedestal. I believe the only criteria were: ground path; positioning in the air flow; and perhaps serviceability.

Note as well, later model years have a redesigned module located on the fender. If the heat path theory had already proved out, they would not have invested in redesigning the locale.

Ken
 
Ken,

You made measurements of a stationary car presumably at idle. As has been stated before and you have yet to dispute as load and rpm rise the output of the DIS Module increases since it is passing more current (total) to the coil packs. There is no doubt where heat is being generated in my mind nor is there concerning the need for heat sink grease. Also as stated in another thread is their confusion by the ex-Ford Engineer I consulted when originally questioned on this subject.

The redesign was not done due to heat concerns of the DIS Module. The high rate EDIS was a design improvement over the earlier low rate DIS system. It allowed more precise control of the ignition event than the earlier system.
 
Aww commone..Heat doesnt rise..There is also a difference between the pedastal acting as a heat sink and heat that may be transfered to the surrounding air.
 
Duffy:

>You made measurements of a stationary car presumably at idle.


The car had been driven up the freeway, to an exit that was less than 10 minutes from home (my car, as I suspect similar to others, runs cooler at speed). I pulled into the garage, where my brother was doing checks on his car - I left the engine running, immediately raised the hood and checked with a laser thermometer. If I thought this was a casual find, I wouldn't bring it up. Prior to this, I had checked the module more than once after driving the car as well as while it warmed up, and found it to always be at the same temperature as the pedestal - this was also confirmed by the thermal images that were taken with the module mounted in stock configuration.

>as load and rpm rise the output of the DIS Module increases since it is passing more current (total) to the coil packs.

How much current is involved? I would expect it would need to be constant in order to work properly. The coil is responsible for building, stroring and supplying the spark energy, not the module. If the module generated that energy, the plug wires would be on it. If heat energy related to the coil were a factor, the coil pack would be at least as hot. I've checked it and it is always well below the temperature of the pedestal/module (<150F). Note that it sits inside a raised bracket, presumably in a similar airflow.

>The redesign was not done due to heat concerns of the DIS Module.

This seems contradictory to the long running history of issues with modules located on the engine. There were known issues going back to the early 1980's. The mid-90's saw the module moved to the fender.

>The high rate EDIS was a design improvement over the earlier low rate DIS system. It allowed more precise control of the ignition event than the earlier system.

I don't dispute any of that. Today we have COP (and another threat of class action suits on related failures - why can't Ford get this right?), etc.

These modules have been continually updated, based primarily on advances in related IC technologies/materials and continuous efforts to reduce component costs, including those affecting warranty payouts.

But why move it off the engine, investing in additional design and materials?

Because of heat issues...something anyone can investigate, just as I did, with proper tools and a minimum amount of time. I'd love to see what info someone else could gather. I know I'm not the only one with a temp gun :)

Ken
 
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"The car had been driven up the freeway, to an exit that was less than 10 minutes from home. I pulled into the garage, where my brother was standing, do checks on his car - I left the engine running, immediately raised the hood and checked with a laser thermometer."

Like I said...car stationary with the engine idling. No one other than Ford probably knows what the actual underhood temps are with the car moving and the engine under load.

"How much current is involved? The coil is responsible for building, stroring and supplying the spark energy, not the module."

Sorry....but that is just wrong. The DIS Module supplies ALL the current that is used by the coil. It is a step-up transformer. The inductance of the coil is what "stores" the electrical energy in the form of a magnetic field which collapses when the plugs fire. Each of the three circuits is current limted by the DIS Module to 5.5 amps for a total maximum current draw by the DIS of 16.5 amps.

"The redesign was not done due to heat concerns of the DIS Module.

This seems contradictory to the long running history of issues with modules located on the engine. There were known issues going back to the early 1980's. The mid-90's saw the module moved to the fender."

I never directly asked the question why the DIS Module of the EDIS was moved to the fender. It could have been as simple as not meeting corporate hood clearance issues (which contrary to some folk's beliefs was the REAL reason the blower top was necked down on the SC). There have been issues related to module failures but more related to the Thick Film Ignition Modules that used to be mounted on the distributors than to the DIS Modules like on an SC. I had one go out in my 83 Turbo Coupe in the left lane of a major highway duing rush hour traffic just outside of Seattle. Likewise it would seem counter intuitive to absorb the expense of going from the Thick Film system to the DIS system then mount the module in a heat prone area all over again if it was a major concern????? Ford does do durability testing to 100K miles on all product. (Corporate standard)
 
Heat does rise....in convection heat transfer. The heat transfer from the DIS Module is by primarily conduction though in that case it moves from the heat source (the module) to the heat sink (the Accessory Bracket) which just happens to be below the module. There is some convection heat transfer to air as well but if it was being relied upon as a major form you would see a different design for the module since plastic is a crappy heat transfer medium and there would be fins to increase the heat transfer surface area. A VERY inefficent form of heat transfer I might add compared to conduction to AL like we have here. Also a reason the top of the Accessorry Bracket is not painted even though the rest of it was/is.
 
>No one other than Ford probably knows what the actual underhood temps are with the car moving and the engine under load.

It's not hard to imagine the scenario at speed. let me know what you find if you do any tests of your own, please. I'd love to know.

>The inductance of the coil is what "stores" the electrical energy

Thanks for agreeing with me.

>each of the three circuits is current limted by the DIS Module to 5.5 amps

With that 5.5 A being constant...not something that fluctuates. Keep in mind that the DIS is solid state, where the coil is mechanical.

>Ford does do durability testing to 100K miles on all product. (Corporate standard)

I've done reliability testing, mechanical and electrical, including short-term lab and long term field. Ford is not alone in finding the reality of production components behaving different from what their engineers report.

My findings show the DIS to be cooler when not in direct contact with the pedestal. Until someone takes the time to confirm or dispute with something other than anecdotes, I stand behind my data. Again, I'd love for someone else to check this out...it's not that hard to do. Put a flat-washer under each corner/screw hole, tighten it down and see what happens. Build and install a heat-sink and check it out...who knows, we could start a new trend and sell the darn things (could probably sell them whether they helped or not...). Less talk - more action. I'm always eager to learn.

In any case, let's not get too emotional over this. Debating any topic is hard enough without the added burden of being text based :)

Ken
 
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>though in that case it moves from the heat source (the module) to the heat sink (the Accessory Bracket) which just happens to be below the module.

Again with the heatsink analogy - fine, when the example is a thermally active computer processor sitting on a polished block of non-thermally active material with a fan blowing down.

In the case of the DIS, it is sitting on a significant heat source with thermal loads shared between both components.

There is little logic in comparing the two designs.

Ken
 
">each of the three circuits is current limted by the DIS Module to 5.5 amps

With that 5.5 A being constant...not something that fluctuates. Keep in mind that the DIS is solid state, where the coil is mechanical."

No...the coil is not mechanical.....it is a step up transformer (electrical) and ALL the power being used by the coil to step up the voltage to the secondary side comes from the DIS Module. The DIS Module has discrete semiconductor devices as well as other electronic components inside of it. While not microprocessor based, it still operates under the same basic laws of physics and electronics as a microprocessor which likewise has transistors, resistors, capacitors etc etc etc....just in a miniaturized form.

When the coil is first energized by the DIS Module it is seen as a short. As the magnetic field rises the current flow from the DIS goes down until the plugs fire then it starts building again so NO the current is not constant. The rate at which current flows rises with RPM since more firing of the plugs is required. Also dwell (charge time of the coil) is adjusted by the EEC as RPM changes. And there are three separate circuits at play in the DIS Module for the three sets of plugs and coil packs (three coil pack pairs per coil assembly).

In the end Ken...you can choose to believe what you want and do to your car whatever you feel is best. However, I am only trying to give the most technically accurate "advice" I can given my engineering background and sources for what was once "inside" information none of us had access to. Also you might want to do some reading on thermodynamics so you don't draw incorrect conclusions from the data you are gathering.
 
Duffy:

>I am only trying to give the most technically accurate "advice" I can given my engineering background

Fine, I appreciate that. I'm sorry you feel threatened.

You've got no desire to check out what I've found and move away from chatter, eh? I'd hoped for something more from than just talk.

Ken
 
Threatened?????? Hardly given I know what I know and know there is much I don't know. In the end...people do what they choose to do but deserve to hear/read both sides of an issue before they make decisions that could end up costing them money unnecessarily.
 
If I can find my ibutton thermocron, and it still works, I'll data log my DIS with it on the pedistal. Then add a spacer and data log it again. I'll do the trip to work, which takes about 30 minutes and has about 20 minutes of stop and go, with 10-15 minutes of 55-65mph driving.

When attached to the pedistal, I can only measure the top surface of the DIS. When I add a spacer, I'll data log the same spot on the top, but also on the bottom.
 
When attached to the pedestal, I can only measure the top surface of the DIS. When I add a spacer, I'll data log the same spot on the top, but also on the bottom.

There is an air gap in the top-middle, as I'm sure you know, and the shoulders seem marginal, but I found as long as I stayed off the connector pockets the temps on the module surface were generally the same. Taking comparative readings between stock mount and lifted should be enough in any case.

Thermo-dots/pencils would work and perhaps be easier, but I like the idea of the datalogger much better.

Frankly I was surprised at what I found and that is the main reason I'm interested in seeing someone else check, thanks.

Ken
 
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For what it is worth - I sent an e-mail to Airtex today and here is the answer that was supplied from them on the difference of their two modules.

_______________________________________________

"There are a couple of differences between these two modules.

The 6H1100 has a 6.0 current limiting to the coil primary winding

The 6H1101 has a 6.7 current limiting to the coil primary winding.

It also has "start input" circuitry which helps with fast start and timing issues.

If you need any further assistance please let me know.

Take Care,

Mark Hicks
Technical Services Manager
Airtex Engine Management
(920)929-6258


shane neuman/fairfield/airtexproducts
04/28/2008 02:37 PM
"
_______________________________________________

Don't know, but it probably applies to the other brands. I should have asked them if they are interchangeable. I will reply back to them and ask about that.

Later
dbd
 
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