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Discussion Starter · #1 ·
The Microplex ignition system

The Microplex ignition system on my 88 328 has been misfiring for some time and I was told it needs to be replaced. Problem is this model has been out of production for some time and those that are available are either used or rebuilt units being sold without warranty. Thought of relying on more recent 348 / 355 units were dashed when I discovered these moved on to Bosch Motronic....if any one have had experience, pleae share the lesson learnt. Thanks in advance.

Leo
 
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Discussion Starter · #2 ·
First of all how do you know f

First of all how do you know for sure it's the Microplex itself and not loose corroded wires or a bad ground?? Then, how do you know for sure it's not one of the more likely suspects a Coil Pack?
 
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Discussion Starter · #3 ·
My own garage (who have fe

My own garage (who have fetted this car very competently over the past five years) and the franchised dealer share the same diagnosis.

When the "misfiring" comes, the engine feels as if it was a Fiat 500 unit and such "misfiring" occurs occasionally when the car is driven without letting the engine warm up fully for 5 - 10 minutes and usually cuts in a few minutes into the journey when I fined myself cruising at low speed in traffic. Where circusmatnces allows, stopping and re-starting always cured this "misfire". Once done, the misfire would not return for the rest of the day.

Last visit to the garage I had my mechanics measured the ignition of both cylinder banks and one side was found to be very weak and it was traced back to the MED 806A. I would not profess to be a spanner man but since this diagnosis was confirmed by the franchised dealer, I am assuming both are not wrong?

Best
 
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Discussion Starter · #4 ·
I cannot remember ever seeing

I cannot remember ever seeing one of these 328 units laydown like you describe, however I have seen many instaces of one of the Coil Paks going bad over a period of time causing a sporadic )such as when cold) problems...in fact I found a sporadic miss problem earlier this year, that after considerable investigation & analysis, proved to be a Coil Pak.

Anyway...to answer your original question...if the seller will give you a minor warranty to nsure the used/rebuilt unit is in fact good, I'd readily go with either one without concern.

Regards, JRV
 
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Discussion Starter · #5 ·
John,

I appreciate your an


John,

I appreciate your analysis. Allow me to clarify one issue. Is your reference to "Coil Paks"refers to the ignition coil or something else?

I read the other thread in which you had earlier advised on the Digiplex on a BB 512i. From what I recall of my garage's explanation, their check on my 328's Microplex sounded very similar to Tom's description of checking the power output of his Digiplex which leads me to assume (rightly or wrongly?) that both my garage and the local franchised dealer are right......

Thanks for your guidance & best wishes.
Leo
 
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Discussion Starter · #6 ·
Leo,

328's have a comp


Leo,

328's have a completely different system than other cars talked about previously. Although test procedures are simular.

Your engine has an ignition computer and Two Coil Units that sit on the left front engine compartment bulkhead. If your technicians are reffering to those two coil units, then they are correct. It's not that uncommon for them to fail as you describe.

They are not that expensive if I remember correctly, on the order of $450 approx. for a new complete unit.

Regards, JRV
 
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Discussion Starter · #7 ·
>>Problem is this mode

>>Problem is this model has been out of production for some time and those that are available are either used or rebuilt units being sold without warranty.<<

Leo,

this is the part that threw me/throws me....the only part of the system that's rebuildable is the Computer...the Coil Paks (the microplexes) are readily avalible NEW for the $450 approx. I mentioned.

The transistor unit (trigger) on top of the Coil Paks (under the black shield) is reportedly the same as 4 cylinder VW's/BMW's and is the portion that most commonly fails and can be purchased seperately for about $60. Maybe by replacing the trigger unit someone is calling this rebuilt???

HTH's

I'll post some pics tonight.

Regards, JRV
 
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Discussion Starter · #8 ·
John,

Thanks for your cont


John,

Thanks for your continuous help. The two ignition coils on my 328 as you described were in fact replaced by my mechanics 3 / 4 years ago and they remain functional. I called my mechanics yesterday after our exchanges and he has confirmed it is the Microplex unit that is giving me grief.

I contacted Perma Tune yesterday and they replied the Microplex cannot be rebuilt but offered a solution in the shape of a Plasma Drive model PD010 from Zims Autotechnics saying this can be triggered by the Microplex so long as it is still firing. I will find time later today to get in touch with Zims to find out a bit more.

In the meantime, I am eagerly awaiting to see your pics.

Thanks & best wishes.
Leo
 
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Discussion Starter · #9 ·
Leo,

I forgot to take the p


Leo,

I forgot to take the pics today sorry.

I don't think the plasma drive is well suited to your purposes. If Zims thinks it is, I'd be curious as to their feedback.

I still find it hard to believe a sporadic miss can be caused by a computer slowly going bad...just is not logical.

As these cars get older they have become notorious for bad and loose connections that cause these types of sporadic issues, or as the other gentleman found a faulty/weak flywheel pickup sensor, likely combined with dirty/loose connections. Of course if this sporadic problem of yours is suddenly cured with a new computer I'll be very very suprised.

For a used unit you should try Bill @ GT Car Parts. Din't have his number at home, but if you need it I'll post it from work in the morning.


Regards, JRV
 
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Discussion Starter · #10 ·
John,

Thanks. I was buildi


John,

Thanks. I was building my hope on getting aftermarket replacement units from Perma Tune / Zims that I hope are built with more modern technology (if Ferrari passed on Magnetti Marelli and switched to Bosch from 348 onwards.....). I will let you know what comes out of the dialogue with Perma Tune / Zims.

I would like to hear your views on buying used Microplex. Maranello Autoparts has one on offer @ $ 11750 (ex 86 Mondial) while Italian Car Parts has one for $ 1250 but neither comes with any warranty and I am worried about the old cardinal rule of "buy cheap, buy twice". My local Ferrari dealer located an unused Microplex in Tokyo for $1700 inclusive (very good value by comaprison) but again no warranty is offered nor could they ascertain the date of manufacture of this unit.

Do you have any views?

Thanks & best
Leo
 
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Discussion Starter · #11 ·
Leo,

there have never been


Leo,

there have never been warranties on electrical items...even new ones from any source..

the obvious reason is that people would buy one plug it in, realize that's not the problem and want to return it...or even worse have an unrepaired short and fry the new part, then claim defective..

Personally, for the small difference in price the new one sounds like the best value. And if it turns out that doesn't solve your problem you could ebay your used one since you know the going rate.
 
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Discussion Starter · #12 ·
Leo,

have you checked with


Leo,

have you checked with Ferrari UK on the Ferrari Owners site? You have to register which is a pain, but they have more parts and better prices than anyone in the world.

www.owners.ferrari.com


I think
 
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Discussion Starter · #13 ·
Gents,

I just checked with


Gents,

I just checked with Ferrari UK....
855 GBP, but not in stock.

David
 
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Discussion Starter · #14 ·
David thanks..if Leo is new to

David thanks..if Leo is new to that site you know how much misery you just saved him...{
}

>>I just checked with Ferrari UK....
855 GBP, but not in stock<<

that's about $1100 US (?) when they were OoS on some 246 sliders I needed for a job they found the rest of my order in Belgum and had them in 2 days..to complete my order...

Leo,

might be worth a try to see if they can round one up.
 
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Discussion Starter · #15 ·
John & David,

I confess


John & David,

I confess to be touched by the amount of trouble you guys are taking....what can I say?

I had in fact got myself registered under owners.ferrari.com and searched with no result before resorting to "open admission of defeat" by asking for help in a forum like this one.

John, being in the trade, you may find the following amusing. To ensure if I buy that unused Microplex that I will end up having a fully functional unit, I even tried to short circuit (pardon the punt!)the "no warranty on electrical / electronics items" by asking the local franchised dealer if an exception can be obtained where I engage them for the installation since I will be buying from them. The answer remains a resounding no and I was told for a 1.5 hr job on installation, they may need to charge an extra 8 - 10 hours for tracing all the wiring connection through the car...... good night.

I have put an e-mail to Zims and will see what they say before deciding on biting the bullet and roll over on that US$ 1,666 equivalent piece of Tokyo sourced Microplex. Given what I have learned on Microplex, I really would prefer to go for better quality after market substitute if they exist. I will keep you posted.

My most sincere thanks to you folks. Have a good day.

Best
Leo
 
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Discussion Starter · #16 ·
JRV

You mentioned these rar


JRV

You mentioned these rarely fail, is the Microplex more reliable than a regular control unit in other cars? I have seen many other types fail regularly.

I bought a 806a spare from a guy a while back who turboed a 89 328, thought I might need it one day,BTW 855GBP is 1340USD
 
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Discussion Starter · #17 ·
Jeff,

I can't remember


Jeff,

I can't remember having ever seen one fail yet, although I have seen many with loose connections and bad ground wires. I even have a used one myself that was "under water", filled, water poured out of it...that I took apart and dried out and it still works like a charm.

Of course you have to figure that over any entire production run every part will fail on at least a few cars...so failure surely occurs...but imo it is extremely rare for the 328 control units to go bad 'on there own'.

Regards, JRV
 
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Discussion Starter · #18 ·
here is the Microplex Unit. in

here is the Microplex Unit. inside resides a circuit board that essentialy collects, then distributes signals.


 
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Discussion Starter · #19 ·
Here is the back side, you can

Here is the back side, you can see 4 screws on the corners that allows the unit to be disassembled for inspection, cleaning or repairs. This is a direct departure from the earlier DigiPlex units that were expoxy filled, purportedly to prevent vibration, but causing heat build up & saturation that led to many premature failures, that is why the new design dropped epoxy filling and led to far longer lasting and more reliable units.

 
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Discussion Starter · #20 ·
here is the CoilPak...by far t

here is the CoilPak...by far the most common portion of the ignition to malfunction. and to the left, the little black unit with connectir prongs is by a large margin, the portion of the coil pak that fails most, and is the piece referenced about that is the same configuration internally as early 4 cylinder VW Rabbits.

 
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