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Discussion Starter #1
I have a 97 900 se 2.0 turbo. Just today, going about 85mph on the highway, it started to misfire. By the time I got to the autopart store, I had a check engine light. It showed the code for cylinder #4 misfire, and I could definitely feel it. Got new spark plugs, changed them, still misfiring. Could this be the DIC? Would it only cause one cylinder to misfire? Anything else to try before spending $250+ on a DIC? Car has 144k miles, 16k put on in the last 5 months (since I've owned it).

Thanks in advance to anyone who can offer help.
 

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Yes, the problem is the expensive DIC. One coil or coil connection has failed, causing a CEL generating misfire.

Is the rest of the service work up to date ?
How were the old plugs ?
 

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It probably is the ignition moduel (DIC). Check the date code on the underside, that will let you estimate how many miles are on it.

Hover, the first thing I would try is to take the casette apart (separate the black plastic lower part from the top (just a handful of screws), and inspect the outside of the coils (the white cylinders). If there is oil coming out of one of them, the ignition module is done. Clean the spring contacts which make the connection between the coils and the top of the plugs, clean the rubber boots, lubricate the boots with dielectric grease, check the plastic for cracks, reassemble and try it again.



You could also try some heavy duty injector cleaner in case one injector is plugged up (unlikely but possible).

Or compression check, which would tell you if a valve in one cylinder is dirty and not sealing completely (that actually happened to me, and with some German valve cleaner product from Lubro Moly, eventually went away).

Unfortunately, in the end, the most likely is still a bad ignition module.
 

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I had the same problem a few months ago and also tried to fix it with new spark plugs, carb cleaner, new air filter. Nothing worked.
Bought a new DIC (I think it was $350). Takes less than five minutes to switch them out. Problem solved.
I wish I had taken the broken one apart though. It appeared to be leaking fluid from only one of the coils. Maybe I coulda fixed it, maybe not.

How'd you get the code so easily? Is there a cheap device out there somewhere that plugs into the car and tells you what's wrong?
 

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jmyers121 said:
I had the same problem a few months ago and also tried to fix it with new spark plugs, carb cleaner, new air filter. Nothing worked.
Bought a new DIC (I think it was $350). Takes less than five minutes to switch them out. Problem solved.
I wish I had taken the broken one apart though. It appeared to be leaking fluid from only one of the coils. Maybe I coulda fixed it, maybe not.

How'd you get the code so easily? Is there a cheap device out there somewhere that plugs into the car and tells you what's wrong?
yeah, Autozone= free Code readings
 

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Discussion Starter #6
REplaced the DIC, still happening. Used some injector cleaner too, and nothing. Next is a compression check?
 

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Jabbit said:
REplaced the DIC, still happening. Used some injector cleaner too, and nothing. Next is a compression check?
That is how we found a valve in one of the cylinders was not sealing. Compression check showed low compression on one cylinder, and later a leak-down test confirmed it.

Same cylinder? Did you reset the ECU and the fault when the ignition module was replaced?
 

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Discussion Starter #8
I assume it was the same cylinder. Replaced the DIC in a parking lot down the street from the salvage yard, disconnected the battery for 60 seconds, fired it up, and it was acting the same. Going to check the code tonight.

Can you walk me through the basics of a compression or leakdown test? Never done either.
 

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Jabbit said:
Can you walk me through the basics of a compression or leakdown test? Never done either.
If you buy a compression gauge in a typical part store, it will have some directions. Since you had the ignition cassette and plugs out a couple times, it should be easy.

Disconnect the fuel pump fuse first, start the engine to use any fuel in the lines, and let it die. Remove the ignition cassette and the plugs. Connect the gauge to one cylinder at a time, crank the engine for a couple seconds, record the readings from the gauge. Look for a low reading from the misfiring cylinder, that would indicate misfire due to low compression.

The leakdown is a bit more complex, you need a source of regulated compressed air with the proper gauges, and a good touch. I did mine with a mechanic and a good leakdown tester. See below for a discussion.

http://www.saabcentral.com/forums/showthread.php?t=113874

Btw, I am not sure 60 seconds is enough to reset the faults in the ecu, but I am not sure.
 

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PMI said:
It probably is the ignition moduel (DIC). Check the date code on the underside, that will let you estimate how many miles are on it.

Hover, the first thing I would try is to take the casette apart (separate the black plastic lower part from the top (just a handful of screws), and inspect the outside of the coils (the white cylinders). If there is oil coming out of one of them, the ignition module is done. Clean the spring contacts which make the connection between the coils and the top of the plugs, clean the rubber boots, lubricate the boots with dielectric grease, check the plastic for cracks, reassemble and try it again.

PMI, I just ordered the lower di part, I didn't just order a $70 piece of plastic did I?
 

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Tweek's Turbos said:
PMI, I just ordered the lower di part, I didn't just order a $70 piece of plastic did I?
I think so.

The lower part (p/n 9167016) is a piece of plastic, with some rubber inserts (boots) to cover the top of the spark plug. No active components.

The coiled spring connectors have a separate part number.

The upper part has the electrical components in it, circuit board sealed with a black glue-like compound. The only parts I can identify are the coil housings (white), the relay and transformer, and the capacitor used in the capacitive discherge cirquit along with the coil, to fire the plugs.
 

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Discussion Starter #13
Ok I checked the code and it's still #4. I bought a compression tester and I am going to try to use it right now. Is it required to take out the fuel pump relay?

Also, could I possibly have a bad injector?


Tweek's Turbos said:
Did you NGK BCPR6-es plugs or no?
Yeah, those are the ones I used.
 

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Jabbit said:
Ok I checked the code and it's still #4. I bought a compression tester and I am going to try to use it right now. Is it required to take out the fuel pump relay?

Also, could I possibly have a bad injector? Yes, however rare this may be. That particular plug would really be carboned up while the others were clean.
And of course, there is the tale of the tail-pipe.




Yeah, those are the ones I used.
The "R" in the spark plug part ID is most important, as is the "6" heat range.
I hope you bought the more expensive screw in type of compression tester.
This compression test is part of an annual tune-up - when this is done properly....
I see no reason to disconnect anything during the test...BUT, I think the DIC should disconnected - come to think about it....
 

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Jabbit said:
Is it required to take out the fuel pump relay?
just the fuse

Jabbit said:
Also, could I possibly have a bad injector?
sure. I have not seen many posts about bad injectors, but you could swap them and see what happens.

And btw, yes, the ignition module should be disconnected to avoid shock hazard.
 

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Discussion Starter #16
earthworm said:
The "R" in the spark plug part ID is most important, as is the "6" heat range.
I hope you bought the more expensive screw in type of compression tester.
This compression test is part of an annual tune-up - when this is done properly....
I see no reason to disconnect anything during the test...BUT, I think the DIC should disconnected - come to think about it....
Those are def. the spark plugs I am using. When I pulled the 4 the first time, the one that was misfiring was basically all black and almost charred-looking. The other 3 were all normal looking.


The compression tester does screw in, and it was only $25. I will def. disconnect the DIC to prevent from being zapped (again) ;oops:

How easy is it to swap injectors? I figured I could switch 2 of them and see if the misfire followed.
 

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Hi there I had a mis start up in my 900s in 2 cylinder :eek: I poked around to find the electric conection on the fuel injector had popped out :) after I had checked plugs , HT, the mis fire had me worried for while . Good luck .
 

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Jabbit said:
When I pulled the 4 the first time, the one that was misfiring was basically all black and almost charred-looking. The other 3 were all normal looking...
I wish you had posted that first, we might have saved you the trouble of trying a second ignition module!
 

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Discussion Starter #19
PMI said:
I wish you had posted that first, we might have saved you the trouble of trying a second ignition module!
So does that mean no compression? Haven't tested yet.
 

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Jabbit said:
So does that mean no compression? Haven't tested yet.
it means you were getting a spark in that cylinder. You can sometimes tell what is going on by the look of the plug, oily/tarry means one thing, dry flaky another, electrode burned/melted another, and so on... you can look up examples of fouled plugs on the NGK web site, and elsewhere.
 
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