94 960 wagon ignition modules questions.

himmelsm · Post by **himmelsm** » 30 Dec 2011, 14:09

The engine started running rough. The dealer said there was no spark on #2 and it needed a new enigine harness and then maybe a new computer and recommended that I retire the vehicle. I thanked them and brought it home. I installed the Barton's spark plug harness. I still have no spark on #2. I swapped the coil packs around and verified that the coil pack is good (problem remains at #2). Come to think of it, I did not verify the #2 plug itself. Do spark plugs fail? They are a genuine Volvo set installed 7/11. I will backtrack and verify the plug. The schematic that came with the harness shows two "Motronic power stage modules (left side of engine near intake manifold)." I see two identical gray boxxes, mounted with the OBD connectors, that say Volvo 889976 on the cover, but I do not think they are it. Can anyone get me pointed in the right direction? The spark plug harness, behind the splice, dives down under the intake manifold and I can not follow it very far. The car now has 177K on it and I am not quite ready to give it up.

danr960 · Post by **danr960** » 30 Dec 2011, 17:34

No, what you are seeing on the fender is the injector relay and ignition relay, identical part numbers.

Most of the harness problems are on the head top, where the heat is. Volvo and their biodegradable wire insulation, just a joke, I think they invented by mistake.

The power stage or ignition modules are located under the throttle body on the bulbeous part of the intake, one forward an one aft. First unplug and replug them, see if that knocks off any corrosion. If not, then swapping them, which, if one is faulty, then the miss will move to another cylinder. If that fails, can you do a compression test? You may just have an intake manifold gasket leak. Not hard to do.

DanR '94 964 368,000 miles (134,000 on the new engine)

himmelsm · Post by **himmelsm** » 30 Dec 2011, 20:12

Thanks DanR,
The Barton harness is a great solution for the baked copper/PVC and rotten loom. My wires looked fine just outside grommet where I made the splice. I wish I would have come across it a few years ago. I suspect the extra resistance from bad wire has caused a transistor in the module to fail. I'll need to figure out how to approach those modules.
Mark

himmelsm · Post by **himmelsm** » 31 Dec 2011, 13:37

Resolved! Ohm-ed out each wire between module and coil pack, all okay. Cleaned all of the spade lugs on each module. Swapping the modules moved the misfire to #5. However, a nastier issue appeared as we were moving the car around. A major Power stearing leak, which may be the last straw.

PaulCrafter · Post by **PaulCrafter** » 23 Jun 2021, 04:40

actualy could be what you need a new whole engine. I attach a link where you can find many variety of them:

https://orbimotors.com/

check pls and let me knoew about that!