Ignition coil or Ignition Control Unit?

cr4b · Post by **cr4b** » 08 Apr 2006, 10:02

Hi, I have a Volvo 940 (B230 engine).

It's been suffering from some strange problems lately. For a while I thought it was cured, but now the problems appear again. A mechanic measured that there was something wrong with the ignition coil and the Ignition Control Unit.

I tried changing the ignition coil to a cheap one that is not specifically designed for any particular car. With the old coil, the car's tach needle bounces all the time. The car also hesitates a little while driving at a constant speed or accelerating. With the new coil, the tach needle is fine! It's just that the idle get completely messed up with the new coil. It runs waay too rich and the RPM is all over the place. I didn't dare to drive it, because it was shaking so badly. It seemed to run better when pressing the gas, though.

Any ideas or suggestions? I'd be ever so grateful if I could get this problem solved. It's just that the Ignition control unit is so expensive that I wouldn't like to replace it in vain.

wojeepster · Post by **wojeepster** » 10 Apr 2006, 19:02

ignition control module on drivers fender, or hall pickup sensor in distributor. Mine was the hall pickup mine would die when hot. I replaced ign control module first, and I am guessing that is where your problem is. Swap a used one in, and make sure you use that white thermal paste or it will fail again. Are you sure it is not your air mass meter? Unplug it and see if it runs better. This puts volvo in 'limp home mode"

cr4b · Post by **cr4b** » 12 Apr 2006, 11:04

I tried to change the ignition coil to a new one from Bosch. This resulted in very strange symptoms. When I now turn the key to the II position, a kind of buzz is heard from the engine and the tach needle jumps straight to around 6000 RPM. But the engine is not running!

I tried putting different coils on it. With the cheap generic coil, the tach worked fine but otherwise the engine would barely run. But with the old Bosch coil the tach jerks a little bit when turning the key to II. Also, a SLIGHT buzz is heard for like 0.5 secs.

I read somewhere that Volvos use a resistor with the ignition coil, and I think that's why the cheap generic coil wouldn't work. It was meant for full 12 volts. Does anyone know where this resistor is located, because I'm thinking it may be faulty?