help diagnosing... won't start. no spark?

Jan 11th, 2003, 09:55 AM

Hello. I'm trying to diagnose a problem with my girlfriend's 95 Sentra (1.6L - 80,000 miles), and think it is the coil. However, since the coil appears to be integrated with the distributor, I want to know for sure before replacing that expensive piece.

Facts:
- Happened "out of the blue". Working fine, then one day, nothing.
- Starter is turning engine (aux belts spin), but NO firing.
- Battery fully charged.
- Gas is making it to the cylinder. (Tested at the fuel filter and the spark plugs are wet)
- Spark plugs are Bosch Platinum w/ 40,000 miles. Look good and gapped correctly.
- Replaced the distributor cap and rotor.
- Test 1: One plug at a time, pulled the plug out, left it in the wire, turned the engine over to look for spark. Didn't see any, or rather, MAYBE see one spark every once in a while, but mostly no spark.
- Test 2: Extra but different(resistance) spark plug laying around. Gapped smaller. Repeated Test 1 above with it and saw much more consistent spark.
- Test 3: Repeated 1 and 2 with new wires. No difference.

Because I saw spark with a plug with a smaller then specificed gap, my thoughts are that the coil just simply stopped producing enough voltage to jump the spec'd gap. Was going to test today by getting replacement plugs and gapping them small to see if the car at least starts.

Questions:
1. Anybody have similar experience?
2. I called one Nissan dealer and described above. They said if it was the coil I should be getting a "check engine" light, which I am NOT. But maybe the dealer is trying to get my business.
3. If it is the coil, has anybody done a modification such that you added an aftermarket coil as opposed to replacing the entire integrated distributor/coil?

Thanks so much. Posts and emails are appreciated.
Nate

Centurion · Jan 11th, 2003, 05:03 PM

No you won't get a CEL due to a bad coil! Sounds like you've got a bad case of the floods. What I would do, and this is just my 10 cent opinion, is put in new plugs, then try it with the fuel pump fuse removed. It should eventually gasp and choke on the residual fuel; then put the fuse back and go. Just make sure you are actually getting a spark, otherwise don't bother with the above. Check for spark at night (with your eyes adjusted for the darkness) and make sure the plug is touching ground.

Madmax · Jan 11th, 2003, 05:57 PM

How's your cap rotor and rotor? I've seen a couple of older Sentra that would want to start and we only had to replace the above to make it work. I would personaly start with that since it's not that expensive and if you haven't replace them in a long time, it will just be worth it to replace them.

Max

azkicker0027 · Jan 12th, 2003, 12:11 PM

the carbon button in the cap could be worn out to the point of not properly delivering enough spark, or voltage, to the other points......check it out, and for the check engine light, it would come on for a misfire fault.........not "a no fire at all type".........but yeah, you might set off some misses at first......