QuestionQUESTION: Mark,
My Volvo is having a fit, well since I've owned it. The
idle has a random sputter, and the tachometer floats but,
occasionally will work. When it does the engine has GREAT
power when not its iffy. I have tested the could + - and
get a reading of 3.89 the books says this is a faulty
electronic module. I have a feeling its a bad coil. Could
you please shed some light O' Guru of the Volvo! :D
ANSWER: Kint, check the basics first. Plugs, wires, cap and rotor. Lastly suspect the ignition module. They are a common failure item though. Especially worse when hot. What voltage are you measuring and on what pins, where? Is it worse when it's wet out?
Mark
---------- FOLLOW-UP ----------
QUESTION: Mark,
Plugs are good I changed them a month ago. As far as the
wires, cap, and rotor is there anyway I can actually TEST
them no just visually inspect?
I was talking about the + and - pins off the coil.
(3.89) supposed to be .5 to 2.0
I have learned a new bit of information since then as
well. When it does float and I close a circuit say the
headlights, fog lights, etc.... the tach reading will drop
from say 3000 to 2700.
Hope this helps some,
And thanks you!
Kent Davis
Answer You can diagnose them with a lab scope reading of the ignition waveforms. O'wise. no. Just replace them as they are relatively cheap. Only use Genuine Bosch parts.
Check all battery and alternator connections for cleanliness and tightness. Test charging and starting systems. Ignore the voltagereading at the coil, it is correct. Be sure main/batt. voltage never drops below 9 volts anywhere on the system. Correct as necessary.
Mark
