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Well after my car missing now and then I got a new DI unit from my friendly scrap yard and a new dump valve too.

With fitting the new stuff I found some air leaks around the dump valve pips so I fixed them and installed the new stuff.

After trying the car it was like night and day and the cars running great so I was a little happy

Then tonight I started thinking about my old DI unit and how could it die?

So out came the tools and open came the DI unit, that’s when I saw that the good people at SAAB filled the unit with some black sealer so you couldn’t get to the circuits at all but I did notice that one of the electric connectors that has the spring connected to it had some black ark where the spring connects to it, so its connection wasn’t the best.

So I pulled out all the springs and saw that they didn’t look very long at all and the spring that was arking was the shortest out of the lot.

So now I have stretched all the springs to the same length and reassembled the unit for testing tomorrow as its night now

What I was wondering is has anyone tried this before? And what happened after you did this; did it fix the missing you had before?

Just to let you know my cars a 93 9000 CSE Turbo

Hi by the way!
 

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Hi M pro and welcome to Saabscene!

It sounds like you've got one of the early DI cartridges which could be pulled apart. Later ones are really impregnable.

I've never actaully discovered exactly what the precise mode of falure on DI cartridges is. Sometimes they can just die completely, others they will just give trouble under acceleration.

What I do know is that buried under all the epoxy potting are several electrolytic capacitors. What do these devices really not like? Heat and vibration... so they'll be really happy sat on top of an engine, won't they?

One thing is for sure- DI cartridges have limited life. Those run in higher preformance engines tend to last even less time.
 

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One failure mode is for the oil to leak out of the bottom of the oil cooled windings, leading to overheating of that coil and eventual death.

Originally these coils were available individually and just pushed in on 3? big pins.

I think the 2nd problem related to the 1st though and made coil replacement non viable, that was, when a coil finally fails, it takes one of the epoxy covered components with it, so leaving you with 1 dead coil, 1 dead red cover and 3 working coils but nothing to fix them too.

Later DI's were sealed so you couldn't remove the cover without drilling out the rivets, they also did away with the tail at some point and fitted a connector at the end of the DI so changing them was far easier.

Andrew
Oh, and the later ones are far more reliable anyway.
 

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Having just replaced my DI unit I'll tell you my experience. The car's a '94 9000 Aero with 136k miles.

I had occasional misfires while motorway cruising on and off for about a year. It would only last a second or two and then be fine again, so I wasn't too bothered. Then last week (at a very very convenient time - 5:30am taking my girlfriend to Heathrow airport. I'm sure you can imagine the language) it started running really badly, with no power at all.

Suffice to say I looked at all the things it might be, blocked air filter, fuel filter, split/disconnected hoses, clean plugs, injectors etc etc... It turned out that cylinder 2 wasn't firing, although the plug was fine and the fuel injector working okay. The obvious suspect was the DI cassette. I tried my DI cassette on MarkB's car and it behaved the same, so I'd nailed it. Since I was going to have to buy a new one I didn't mind taking the old one apart to have a look. There were no signs of arcing anywhere, and all the springs looked the same. All the oil filled coils looked the same with the same amount of oil in them. So, something sealed into all that resin had failed for coil 2, but who knows what!

147 quid for a new one from Haymill Saab (185 but with a 20% discount for being a Saab Owners Club member) and all's well again.
 

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What p****s me off is not just that these cartidges are dear at £180squid, but what on earth possessed SAAB to add the horrible white plastic connector at the end

Could they not have designed a better connector that concealed all the coloured wires and nade not quite so fffffffg obvious!!
 

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If the prices of a conventional ignition system are totted up,the DI unit represents very good value,and thats ignoring its superior performance.How many engines can cover 100,000 miles without renewal of some componant?
 

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If you look at what is being done in American Hot-Rodding these days; you will be amazed to see the idea of a crank fired ignition expressed as something new and cutting edge. I have run crank-fired ignition systems on my Porshes back in the late seventies with very good luck. I was impressed to see a similar system under the hood of the car I purchased. Not your average 4 door sedan!
 
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