[mark e]

Some very interesting DI info from Andy M in this? thread on the 9000 forum.

Well A month down had a major service and still no joy all the mechanics were baffled!. So as anyone who has a dad as a mechanic would do!!!Got out the wd40 and sprayed all the terminals around the DI cartridge and then turned it upside down and sprayed down the ends where the plugs make contact, Rinsed it a couple of times put her back together and fired her up  My God it idled perfect and drives like its made 30bhp. Wow its better than my last car(what isn't) Anyway after months of thinking I'd bought a nail hey presto a cheap can of lubricant and its just amazing.[/b]

New DI cartridges have silicon grease in the plug sockets to help prevent ingress of moisture and provide an insulation barrier.

It appears that the problem with Andy's DI cartridge is that one or more of the sockets may have had some dirt/contamination causing an insulation breakdown, and thus loss of spark energy.

So, it may be that some intermittently faulty (esp under high boost) DI cartirdges are not faulty at all, but just need a clean and re-application of silicon grease. I will post a follow up later today with pics of how to do this.

 

[TheFox]

Very interesting reading.

Hows's Bubbles these days? Do not seem to hear much about it?

 

[mark e]

Bubbles is not too bad- just back from the body shop after an altercation with a Renault 5

Have now got to spend some time fine tuning the performance prior to trackdays

 

[Andy M]

Hi all,

May I add that before i couldn't get the car to accelerate over 110mph(on a track of course). Now its a blessing the power(all be it a LPT)is great for such a big car. And thus i will be keeping the DI cartridge well lubricated in the future may save a few quid on a new DI. Cheers hope it works for all who read my post.
Happy

 

[sgould]

It does trigger the thought that, if this is the start of DI failure, that it is finished off by leaving it in this state until the high voltage "tracking" melts or passes through the casing and gets into the low voltage electronics.

 

[mark e]

Some pics to help then

DI cartridge and it's cover separated

One of the "boots" and a spring showing it's relative depth position inside the boot

The dried silicon/other deposits around the nose of an old unit with misfire problems.

Although a fantastic idea, the DI cartridge is inherently going to have a limited lifespan due to the operating conditions. For example, the sharp eyed amongst you will be able to make out an electrolytic capacitor potted in the main body. One of the things that significantly shortens the life of electrolytic caps is heat- so it's inevitably going to have a hard time sitting on top of an engine!

The spring is used as a conductor between the coil and the top of the spark plug. From the picture, it can therefore be seen that it's only the bottom section that needs grease applied.

If you want to clean out the boot section, first remove it from the main body and then use brake cleaner. Spray it in from the spark plug end to get rid of any deposits, then re-apply silicone grease.

I have had problems previous with a cracked spark plug causing tracking and then leaving a deposit which I cured by doing this.

I removed the DI cartridge in the pics as it was giving problems under high (> 1bar) boost. I will try a thorough clean/re-grease etc and see if it still has the problem.

Silicone grease is available from Maplin, part no RE81C for a spray aerosol or RE90X for a 50g tube.

 

[serjeant]

This is ideal for me = my level of mechanics. Thanks.

I will give it a go on mine and report any changes.

 

[1989agoodvintage]

Well I'm going to have a play with my old DI cart tonight, I could use the spare cash so it may be on the classifieds if this technique works.

I noticed that you specify brake cleaner, will a general use electric contact cleaner do the job, or is that not quite strong enough?

 

[Andy M]

hey jason,

I originally used good old wd-40 which gave mine a second life its a good cleaning solution but I'm going to completely strip mine down and do what mark has advised just to make sure the performance lasts

And it even improved my fuel economy.

e.g before returning 22.3 to 22.8
now i'm seeing between 25.8 and 35.4

But mine is a 2.0LPT.

That was by just using wd40 and know striping of any kind.

Good luck

 

[Andy M]

After a week mine started to drop on fuel economy again so today i performed Mark E's service above and with slow but excellent results although I put silicone grease from one end of the the funnel/boot to the other after cleaning and my economy and performance has come back. Just a matter of time now to see if it lasts.

Cheers all

 

[tedward]

A few thousand miles ago my 9000 refused to start full stop. It had been been increasingly hard to start for a while. After a full diagnostic (fuses, fuel pump, relays etc) I finally got to looking at the DI cassette.

Finally "googled" my problem and found this web page

Sure enough I removed the shroud and three of the four coils were emtpy or half full of oil. It was a miracle it had been running at all!
Quick trip to the local breakers (on my pushbike in a rainstorm naturally ) and all fine again.

 

[mark e]

Welcome to Saabscene tedward_9000

There are indeed two styles of red DI- the earlier one like you have which it is possible to change the coils on, and the later ones which are fully "Potted" and you can't change anything on.

The cleaning procedure will work for both however