replaced DCI cassette

My mechanic diagnosed repeated "stuttering" of the engine as a fault in one of the two DCI cassettes. According to the diagnostics, there were several thousand misfires recorded for cylinder 2. Given that this was a big time expense (over $400 for just the part), I'm worried. What's the lifetime of these things? Is the other one likely to fail?

'99 9-5SE V6 (US model)

Reply to
Steven Stern
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The DI cassettes are a fairly common failure items on the 4 cylinder cars, so I would imagine they also fail as frequently in the sixes. You might want to pick one up (/

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has them for $330) and have it on hand, just in case. Be sure to store it in the normal orientation so the insulating oil inside the coils settles to the bottoms.

-Fred W

Reply to
Fred W.

I paid them $237 including shipping for an NG900. It's a five minute job to change it. Don't pay the dealer $0 + labor to do this job. You'll need one sooner or later so you might as well buy one, install it, and see what it cures.

Reply to
-Bob-

This one was for a six cylinder. I was surprised at the high cost too.

-Fred W

Reply to
Fred W.

This site is interested in hearing from you regarding. DIC.failure.

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justsid

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Reply to
justsid

Well, I suppose you get two more cyls' so you pay more. As a comparison, Nissan uses 6 individual coils on the 6-cyl DOHC motors at about $75-90 each... so the price is comparable. They have an advantage in that you can replace just the bad coil at $75 each.

Reply to
-Bob-

No, actually there is a seperate DIC for each bank in the *V*6, so you potentially get to buy two of them, and each one has one less cylinder. That's why it makes no sense at all...

-Fred W

Reply to
Fred W.

I wonder if there is any reason why a remote coil pack can't be made up if you can get the plug leads right? I wonder if direct contact with the plug head is an absolute requirement?

Has anyone here ever taken a DI apart to see how it ticks?

Reply to
Dexter J

I prowled inside my old one. They pour some liquid plastic of some sort that hardens around everything. There's no way to do anything to the unit except replace it.

Reply to
-Bob-

Yes, it is either some black gooey or sometimes oil. I can't imagine that they wear out linearly so to speak. The one I looked at, the windings in one of the coils had melted the insulation material and presumably short circuited the coil. Hence, what kills the DI must depend on the number of times you're stuck in a traffic queue on a hot day with insufficient engine cooling.

Reply to
Johannes H Andersen

Now that is interesting. I was reading up on the unit and it's engineering history and noted that they went out of thier way to "seal" the plug and coil bay in the head claiming that it shielded the rest of the car from radio interference and limited the potential for tech shock (in addition to 'the many amazing new Trionic - yada-yada-yada' guff)..

At the end of the day though - it seemed to me that the whole unit must naturally act as a heat sink when tempuratures rise, which in turn boils the extemely hard working coils and drys out the rubber insulators. Maybe the answer isn't getting the coils free of the head to replace them individually - but rather - to keep the unit within operational temp limits.

I wonder if there is any way to get a little breeze in there with a mini fan? I guess the problem would be making sure it remains water tight and condensation doesn't form on foggy nights.

PS: My ISP newserver (UUNET.CA) seems to be failing to show several posts (according to google). If I've not replied on a thread or don't seem to be noting comments - it may be that I'm not seeing them. Anyone recommend a good free AND reliable news service or is it time to expand dexterdyne.org into newsfeeds too?

Reply to
Dexter J

Try

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- fast, free and relatively spamfree! HTH Julian

Reply to
Jools

This in fact is the apparent weakness in all coil-over systems. I don't know any of them that don't start failing at 60-70K miles. My first experience was on a Nissan I had. As soon as I looked at the design I realized that they were baking in the location they place them.

Perhaps a heat sink unit on top of the aluminum cover ? I don't know if the engine compartment itself is cool enough to make it worthwhile though. Perhaps lots of "fins" installed on the surface would do it.

Reply to
-Bob-

Salutations:

Actually I have access to surplus issue heat sinks - as big as 20x20x2 inches.. However, I'm pretty sure the problem would be lower in DI unit cabin. The paint doesn't seem to peel - so can't be all that hot on the top of the DI.

I think the problem is that the heat being generated at the top of the head is simply radiating into the DI and, in addition to the heat being generated by the coils, is raising the DI temp above it's engineered limit. The good folks at Kawasaki racing cleared some extra breeze channels into the head on my old Z1R to cool things down for sort of the same reasons. Ballast resisters sit just above the head on the frame and the main timing chain runs between #2 and #3 - given the tall cam decks it can get really hot in there.

Anyway, individually the DI operates at X and the head domes operate and Y

- but as things start to get hot and old - I wonder if the "special" DI alloy starts to act as a heat sink for the rest of Head?

I think I'll poke around after the Feds clear our new (to us) Aero into Canada. Anyone got a dead Red DI unit from a 2.3 9000 block they'd be willing to donate to milling research?

Reply to
Dexter J

So you're thinking that we can mil slots and blow air into the compartment ? Might work... a push pull arrangement would be ideal. You'd probably have to pull the intake through a tube to get outside air but that would be easy to rig. I'd bet that a small "computer" fan would do the job rather well...plenty of CFM for that small space.

Getting through a $300 DI w/o damaging it would be the key. High risk for the first couple guys that sign on :-)

Reply to
-Bob-

Well - was thinking we'd want snorkels (to preclude water ingestion) and a temp trigger so it would run after it was shut off (short hops - stop and go traffic). I thought it might also be possible to rig something off the main fan if I worked from the tranny side of the head and vent through the top. Depends on operational temp range of the DI and just how hot it runs in the DI cabin. Also depends on whether or not the coils are in fact being baked by the head or are simply too lightly built for the job.

Whatever the case - the trick would be to get it all hooked up without cutting into the DI circuitry. I'll buzz over to my dealer here in Halifax and see if they have any dead DI units around to see how they are laid out.

Reply to
Dexter J

I think it's a heat issue, but that's only a guess. Every car that I've run into with this system has the same problem with early burn out. The only common thread is the heat/location - that is, they all sit right on top of the cyl's. I know Audi/BMW had a problem with a Bosch coil recently where they wore out in 30K miles... so many that people were waiting weeks and months to get their cars back on the road. That was probably a "too light for the job" problem. Just a seat-of-the-pants guess though in both cases.

Bob

Reply to
-Bob-

The problem is also the cramped space for the coils, that limits the gauge of the copper wire and hence it heats up. Perhaps if they used gold wires instead, the heat could be reduced since gold has higher conductivity :-)

BTW use of gold. The most expensive road car AFAIK was the McLaren F1 supercar £650,000. They used gold foil in the engine compartment to shield the GRP body from the engine heat, it costs a fortune.

Once saw them racing on TV. One McLaren F1 came round the corner and smashed into another...McLaren F1. I felt sick!

Reply to
Johannes H Andersen

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