Defective Coil Pack Symptoms

[Marl1979]

After getting my defective coil pack replaced, I thought I’d give you a list of symptoms to identify this problem. I looked in the forums quite a bit and was able to piece the information together but I thought I’d share a detailled list of symptoms so others can identify the problem more quickly. Maybe this has been done before, but just in case here it comes:

• The car starts running very rough, especially at low revolution (between 1-4K RPM) and you can feel it shake in the stick and pedals. Seems less apparent >4K RPM.
• I noticed a different sound (louder than usual)
• Smoke from the exhaust not coming out as a steady stream but in chunks (“puff puff puff”) instead of the usual steady (“rrrrrrrrrr”)
• Very noticeable lack of power
• Sometimes, the RPM drops while accelerating (RPM would drop from 3.5K to 2K for no reason at open throttle)
• Sometimes, the SES light comes on and/or blinks while accelerating
• The SES code was [P0302] CYL 2 MISFIRE

I know there are other problems that can cause these symptoms but if you’re experiencing something similar, you should get your coil packs checked (or check them yourself).

Please feel free to add to this with any relevant information!!

[NmexMAX]

You have all the symptoms of failing coil packs.

[Snypa]

he sure does....thanx for the info man.

[Marl1979]

I thought I'd add the information on how to test the coil packs yourself to make it a more complete thread...

Originally Posted by multiplexor

Mods remove if you will, i figure it might be handy

How to verify if your coil packs work!
Engine worked with: 1996 maxima
Requires: An ohmmeter (cheap purchase at radio shack....)
Conditions: Make sure your engine is cold, or it'll be hot on your hands
you have 6 Ignition coil packs. 3 up front and 3 near your firewall. (when asking for new ones, they are referred to as L and R)

3 are hidden behind the plastic piece on your engine that says NISSAN... simply remove the bolts and remove the plastic piece.

once removed, you should see 3 coil packs. un plug and test them one at a time.

I won't go into how to remove them since it should be fairly obvious Simply remove both bolts (do one coil pack at a time...) and pull the coil pack out. i had one where it was very hard to get out... so you may have to pull hard...

Once out, look at the area where you removed the electrical plug. You should see a "+" on the back end of the electrical plug. There should also be the letter "B"....
the spot where you see the positive symbol, means that's prong number one on the electrical connector.

To test:

Turn on your ohmmeter and place the positive wire on the 1st prong in the electrical plug of the coil pack. The negative wire should be touching the middle prong. Verification of the ohmmeter at this time should say "0" aka infinite... if it's anything else, the pack should be changed. Next test: reverse the wires... positive on the middle prong and negative on the 1st prong.... on a new coil pack, it should give a value of approximately 1.3-1.7 mega ohms. If any of the readings are off, replace the coil pack.

Note: Firewall coil packs are extremely easy to find, simply look in the cracks of the intake header. you'll see 3 similar looking coil packs to the front ones. The exception with these is that they are longer and look a slight bit different. removal is the same process as the front coil packs. Simply pay special attention to not dropping the screws in the intake area... it'll be hard to get out

to test: follow the front coil pack testing method. Look for the Positive symbol, this is your first prong... and go from there.

Good luck...

[meseville]

Can the reading be slightly over 1.7 Mohm and still be good? 1.875 Mohm?
Bob

[Stephen Max]

Hmmm. Usually when testing resistance with a multimeter it shows 0 when there is continuity in a closed circuit with no resistance. Infinite resistance is indicated by something else, like a dash or some other non-numerical display.

Another problem with testing resistance to determine failure of a coil is that ignition coil failure is almost always an insulation breakdown when the coil is hot, so you should test with a coil that is up to temperature. Even then it may not indicate anything is wrong, since insulation usually fails when there is (significant) voltage present, and a multimeter is not going to give enough voltage to cause an insulation failure. So you may end up with a false negative (i.e. no indication of anything wrong) with this method.

A high-pot test would be conclusive, but that takes special equipment that the home mechanic doesn't usually have.

[ShinseiRyu]

Failing injectors can cause the same symptoms but it is easier (and probably best) to check for failing coil packs first.

[acercomp71]

Originally Posted by meseville

Can the reading be slightly over 1.7 Mohm and still be good? 1.875 Mohm?
Bob

Dont' worry about exact numbers in Ohms, the bullet-proof method is comparing the coil resistance to a healthy coil resistance. For instance, if one coil goes bad, it will give you different ohmmeter readings compared to others. Little trail and error will pinpoint failed coil eventually.
Also, when you buy a brand new coil, CHECK it again and compare to any healthy coil that is already on your car- they should read same readings. Beleive it or not, I bought a defective coil at O'Reiley a year ago and decided to test it just for fun, and it showed OPEN circuit, meaning, when the ohmmeter leads were reversed, it showed "infinite", test every electronic component that you buy from autoparts, they are selling defective stuff sometimes.

[Love_00_Max]

Pinging is common on failed/failing coil packs.

[tosheto]

Originally Posted by Marl1979

I thought I'd add the information on how to test the coil packs yourself to make it a more complete thread...

Thank you man. That is very helpful info.

[Stephen Max]

I'll repeat what I said earlier, since maybe it wasn't clear. If you use a multimeter, the resistance of a coil pack may look normal even for a faulty coil pack. So if the resistance you get is way out of spec, then the coil is definitely bad. But if it isn't out of spec, it may still be bad.

[bamboomerang]

Thanks for the heads up. Just got me some backups from a 200$ (running but rusted out) parts car.

[Marl1979]

Pay it forward