I just changed the plugs in my car and attempted to test the coils with a cheapo ohm meter. The manual says that the proper readings are obtained when the coils are 77 degrees F. Well, how the heck does one get them to that precise temperature? It was cold in my garage and each coil measured a 0 resistence on the nose. I attempted to heat a couple of them up via placing them over a space heater for a time, but there was no difference in the readings. I do have a bit of rough idle and would like to be sure the coils are functioning up to par. Do you test the coils immediately upon removing them from a warmed up engine?
testing coil packs
- Thread starter Doc308
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I think you need a better ohm meter :biggrin: The resistance should go down as the temperature goes down so you should measure a little less then the spec.
As Brian says you probably need a better meter - you probably don't have the resolution on your scale to read 1.0 +/- 0.1 ohms - that is going to look like zero to most analog meters (unless you have a selectable scale where you can set it to a full range of say, 10 ohms).
You're most certainly not going to see a huge degree of difference within most normal range of temperatures either - maybe a few tenths of an ohm at most, which again will be indiscernible.
You're most certainly not going to see a huge degree of difference within most normal range of temperatures either - maybe a few tenths of an ohm at most, which again will be indiscernible.
I had to look up the spec. but it's 0.9 to 1.1 ohm which is not much resistance. As long as you see something close to that range you are fine.
Thanks--as always!
Just checked mine last night and they were all consistent at 1.5 ohms - that OK? Temp was about 70 at the time.Briank said:
Especially since they are all the same I wouldn't worry about it - still probably a symptom of a reading that is not quite accurate.m3456y said:
You are really looking for something that is more either a dead short or complete open, although a low resistance could indicate some of the coils are shorting out but that scenario is less likely.
All of them being equal probably indicates that they are fine.
I have a good quality VOM (meter) and all of mine measured a consistant 1.4 at about 80F.
I've also been tuning+datalogging for a couple of months now...everything is good, so I would assume this is a good data point (1.4 ohm at ~80F).
Drew
I've also been tuning+datalogging for a couple of months now...everything is good, so I would assume this is a good data point (1.4 ohm at ~80F).
Drew
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