960 intermittent stumble: ignition module?

tomatoes4all · Post by **tomatoes4all** » 04 Nov 2012, 21:26

Hello all,

My 1992 960 (with 1995 engine) has an intermittent stumble between 1800 and 2300 rpm and idles poorly, like it's running sometimes on 5 cylinders, but not always.
I replaced all 6 coils last week, thinking that being the cause, but no change. Last year I had the same issue, at least quite similar and after the ignition module was replaced, the problem disappeared.

3 questions for the more learned than myself: How long is this Bosch module supposed to last? Are there really 2 of these modules? I can only see one, even with my reading glasses on....
Is there a way to test this unit and if it is on its way out again: will it just die or will start to malfunction intermittently and cause my problem?

Thanks for the help,

Best regards, Erik

Post by **billofdurham** » 05 Nov 2012, 12:55

How long is this Bosch module supposed to last?

How long is a piece of string? I haven't ever found a manufacturer of electronic parts who is prepared to say how long they will last.

You have two ignition modules mounted at opposite sides of the manifold as in the attached:

960 ignition parts.pdf: (373.53 KiB) Downloaded 960 times

(Ignore the year yours is the same.)

The only test I can find for the ignition module is for the earth connection:

960 ignition amplifier check.pdf: (19.26 KiB) Downloaded 680 times

Bill.

Gatewood · Post by **Gatewood** » 05 Nov 2012, 21:45

May be the ignition module or several other things. Each of the modules controls 3 of the coils. I forget which one, maybe it was 1,3,5 on the front one and 2,4,6 on the back one? Don't take my word for it, look it up somewhere.

If you're getting any type of misfire, it could be the wiring to your coils, That tends to happen a lot with these cars. Check where the wires go into each coil for any decaying insulation. You can buy replacement wires like this at FCPEuro (or IPD):
http://www.fcpeuro.com/products/volvo-e ... vo-3523813.

This guy sells entire wiring harnesses for the coils, but I'd go the cheap way above:
http://www.davebarton.com/volvoharnesses-960.html

Also check the intake manifold gasket. Heh, check it last, cause it's a pain. When I checked mine, I was disturbed to find several of the bolts loose, less than hand tight loose. I had rough idle and a misfire on #2 and it turned out my manifold gasket was bad at #2. Runs smooth as butter now.

tomatoes4all · Post by **tomatoes4all** » 08 Nov 2012, 21:32

Hello Bill and Gatewood,

Thank you for your respsonses.
The wiring to the 6 coils is in good order, the new inlet manifold is sealing well, the spark plugs are new, the ignition coils are new and I have just replaced the old ignition module. Still the stumble and bad idling! Swapped the "old" ignition module with the front one that's only a year old: Still no change! GRRRR, this is annoying... When the stumble and the poor idle happen at the same time, while accelerating from a stop, there are some times a few faint backfires. Nothing violent, but back fires nonetheless. Does any one have a better insight than I have regarding this problem? Mine involved large quantities of explosives; well, you get the point....

Gatewood · Post by **Gatewood** » 09 Nov 2012, 07:22

Not sure if I understand what you said correctly, but did you check BOTH ignition/power modules? The second one is on the opposite side of the manifold 'ball' as the first one.

I know these things are frustrating, hang in there.

Post by **billofdurham** » 09 Nov 2012, 12:09

If you switched the old ignition module for the new one and the old one is faulty you have moved the problem to the other three plugs.

Unfortunately the only test I can find for the ignition module is for the earth.

Bill.

tomatoes4all · Post by **tomatoes4all** » 11 Nov 2012, 02:21

Hi Bill,
Your train of thought makes sense, I'll swap one with the old one and see if it makes a difference.

After resettting all codes only one has come back: 121, which relates to the oxygen sensor. Could a faulty oxygen sensor have such a profound effect on the general drivability and idling of the car? I always presumed it was for cleaner combustion only.
Cheers, Erik.

Post by **osman** » 11 Nov 2012, 09:43

My S90 was doing the same thing but only when cold. Is the hesitation all the time or does it go away once the car warms up?

tomatoes4all · Post by **tomatoes4all** » 11 Nov 2012, 13:17

It's running good with a cold engine, but starts to do funny things when warm. When hot (idling in traffic with aircon on during a warm Australian day) it runs terrible.

CoOlCat · Post by **CoOlCat** » 10 Nov 2020, 10:49

billofdurham wrote: ↑05 Nov 2012, 12:55
How long is this Bosch module supposed to last?
How long is a piece of string? I haven't ever found a manufacturer of electronic parts who is prepared to say how long they will last.

You have two ignition modules mounted at opposite sides of the manifold as in the attached:

960 ignition parts.pdf
(Ignore the year yours is the same.)

The only test I can find for the ignition module is for the earth connection:

960 ignition amplifier check.pdf
Bill.

These blurry PDF's are the best we got???? 4K TV's HD ...and we get a blurry drawing...