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Discussion Starter · #1 ·
First the car quit completely

First the car quit completely while running at 60 mph. I found a dead cell in my battery and replaced the battery. It was backfiring and one bank was running richer than the other. When I replaced the battery, the car ran great, just like it was supposed to. The alternator is putting out 13.86 volts. That euphoria did not last long...again, with a full battery charge, the car started backfiring and acting like it had no power. I have checked the fuel pump fuses (actually had fuel pumps repaired/replaced recently) as well as having one FD cleaned...it was a mess. I think it is the digiplex... but am not sure....should i check the output of the digiplex and how do I do that? Help someone. I have no mechanics near me that are not afraid of Ferraris and I am tired of hauling cars 120 miles to nearby cities and having someone give me crappy service for lots of money. Thanks.
 
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Discussion Starter · #3 ·
After disconnecting the batter

After disconnecting the battery, I would disconnect the connection to the digiplex and clean the terminals...both sides. Reconnect the digiplex, then the battery, and check it out. Could be just a loose connection.
 
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Discussion Starter · #4 ·
Coach,

It very likely is th


Coach,

It very likely is the Digiplex. The only foolproof method I know of checking them is to plug in a Known Good Unit to see if the problem disappears.

Maybe one of the other guys here knows a different trick?

If it turns out to be the Digiplex you have 3 options, a new one, a Perma-Tune unit they install in your original Digiplex Outer Housing, retaining Stock wiring & appearance, or an MSD Mod.

http://www.permatune.com/Products/Ferrari/Ferrari%201512.htm

Regards, JRV
 
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Discussion Starter · #5 ·
I have AEC 104 I believe on my

I have AEC 104 I believe on my daytonas...but there are two of them, so I cannot use one from there because they control 6 cylinders ignition wise ( I actually don't have them connected..they make too much noise and they don't make the car run any better). But the point that this module needs to be tuned to 12 cylinders...right?
 
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Discussion Starter · #6 ·
Coach,

The Boxers use the A


Coach,

The Boxers use the AEC104B-660, not sure if the Daytona unit can be swapped but if the Daytona unit has a 12 cylinder function and the same 6 wire plug it may work.

One thing about the Boxers and the Digiplexs in particular, when they have erratic running problems and it can't be traced to the Fuel Pump fuses it is almost certianly a Digiplex going bad, and truly they don't seem to need a reason to pack up & fail.

JRV
 
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Discussion Starter · #7 ·
JRV, I did some checking. The

JRV, I did some checking. The daytona units which were not the original ones were actually AEC-104 BW and they are identical in size to the AEC 104B-660 which is on the boxer. They have the same 6 wire plug and it appears that 660 limiter can simply be taken off the boxer unit and screwed into the daytona unit...not sure as I have not taken the boxer unit off yet. It seems that with that 660 limiter attached on (?) they are the same unit...any ideas out there?
 
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Discussion Starter · #8 ·
CoaachI,

I suppose if you&#


CoaachI,

I suppose if you're not using them on the Daytona anyway,...then there is nothin to lose, might as plug it in and try it. It will either start or it won't. The one question in my mind though, although I'm very curious to know if they will crossover, is that if it runs poorly on the Daytona unit I don't think it proves the Boxer Unit is good of course if you swap and it does run well again, then it does prove the Boxer unit is bad. .


Regards, JRV
 
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Discussion Starter · #9 ·
Coach,

As best as I can rem


Coach,

As best as I can remember, the ignition units themselves are very, very similar, model to model...The big difference between units was only the plug-in rev limiting module. Although I'm not using the Digiplex on my BB anymore, the model number is AEC 104BK...also with a six wire plug.

Personally, I'd give it a shot...

Regards,
David
 
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Discussion Starter · #10 ·
Thanks JRV and David. I am pl

Thanks JRV and David. I am planning to tackle the project today/tomorrow. Take out the Dixiplex, unplug the rev limiter, plug it into the daytona one and see what happens. I have two daytona dixiplexes which I bought some time ago, installed them, didn't like the hissing and disconnected them. The daytona runs great without them, though I have thought about some more modern replacements such as MSD units for the daytonas. Any opinions there...do these things actually work? Daytonas (2 of them) run great with these units not wired in.
 
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Discussion Starter · #11 ·
Coach,

If you decide to go


Coach,

If you decide to go down the MSD route, I have alot of experience in this area. There are a few posts, for reference, in the Technical Section concerning BB ignition issues, tune-up etc...

I've been running an MSD unit in my BB for the last 18 years...They work very well, but selecting the corect one for your application is important.

Regards,
David
 
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Discussion Starter · #12 ·
David, JRV and anyone interest

David, JRV and anyone interested: The problem with the backfiring and poor ignition is NOT the digiplex nor the fuel pumps...after six hours of testing today, it finally dawned on me what was wrong: remember, I had said that I had one bank rich (with fouled plugs) and the other perfect? Well, there is too much gas going through on that one bak, it is way too rich, and unburnt gas is accunulkating in the exhaust and backfiring there. I am sure of it. I had that FD rebuilt and probably it was not rebuilt to specs. I have tried to back out the mixture screw to lean out the mixture but it does not good. So I keep my gipilex and look for the gentleman who rebuilt that FD, return it to him and have his rebuild it again..the darn thing is sending too much fuel into that bank. Pure and simple...that bank really is rich. It can backfire so much and then also it will quit firing..and the car dies. I think you will agree with my anaylsis...please tell me if I am wrong
 
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Discussion Starter · #13 ·
Interesting, indeed.

One ba


Interesting, indeed.

One bank rich...FD rebuilt and no response to mixture adjustments. A hunch would be either:

-Stuck/sticking FD plunger
-Warmup regulator toast

...with the FD plunger being the most likely candidate.

With CIS pressure gauges, you could confirm the operation of the regulator...

Even if the FD turns out to be the problem, you'll still need an exhaust gas analyser to set it up properly.

Regards,
David
 
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Discussion Starter · #14 ·
>>-Warmup regulator to

>>-Warmup regulator toast <<

Before I would go any farher, it would definately be Fuel Pressure Test Time.

Also....it is important to know if the warm up regulators still have the factory crossover tube.

The problems here can easily be tracked down by some careful methodical checks of several different things to isolate and pinpoint the exact problems.

1- Fuel System Pressure Test.

2- Distrib cap & Rotor condition check.

3- Depends on results of fist two

Also, have to know if FP crossover tube is in place or not, first & foremost, by a simple visyal inspection..
 
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Discussion Starter · #15 ·
All the answers aren't in

All the answers aren't in yet, but I don't see how one side can shut the engine down at 60mph.

Seek and more shall be revealed to us..

Regards, JRV
 
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Discussion Starter · #16 ·
Can you give me a brief descri

Can you give me a brief description of how to check fuel pressure on each bank?
 
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Discussion Starter · #17 ·
Coach,

to test the Fuel Pr


Coach,

to test the Fuel Pressure on cars with the CIS type system like Boxers and many others requires a CIS Fuel System Pressure Tester that plumbs in between the warm up regulator and the Fuel Distributor.

I think there is a pic of one below at: well I can't find the pics, which means we need some in the permanent tech archives so that they can be found easily. I'll take some pics today and post tonight. In the mean time maybe someone can post links of where to get the tester.

Here is a link to what the Warm Up Regs. look like on a TR (basically the same n Boxers). Scroll down, circled in yellow.

http://www.ferrari-talk.com/discus/messages/5/634.html?1062705546

The tester just plumbs in and reads Fuel Pressure which is the critical factor in determining CIS operating condition.
 
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Discussion Starter · #18 ·
another interesting question:

another interesting question: my FD on the left bank (driver;'s side) has an electric connection to it as some type of control, but the right bank (which is the passenger side and the rich culprit) does not have one nor did it ever have one. I will try and find a pressure gauge and try to hook it up to my FD. Thanks...I will post
 
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Discussion Starter · #19 ·
Hi Coach,

that electrical p


Hi Coach,

that electrical plug situation is normal.

Only one side has the Fuel System Safety Switch wired in. It is an electrical circuit that shuts off the fuel pumps if the engine doesn't start to prevent flooding.
 
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Discussion Starter · #20 ·
Coach,

I still need to know


Coach,

I still need to know if your engine has the crossover pipe between the 2 Aux. Fuel Press. Regulators.

Thanks, JRV
 
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