Hi everyone, I am having an issue with my 04 civic coupe with the d17a1 motor in it. It started having this issue a couple months ago where at night the headlights and interior lights periodically pulse as im going up the road...sometimes it does it and sometimes it does not. When it does this I notice the car will lose some power as well as occasionally sputter kind of like a misfire. I had the battery as well as the alternator checked and they both checked out fine. I cleaned and checked all of the grounds and the problem seemed to not happen near as much for awhile (maybe coincidence). Now today I filled up my car with gas, drove maybe 35 miles and it has used over a quarter of a tank of gas as well as started having the pulsing issue way worse than before. Today I also decided to replace the eld to see if that would make a difference and it didn't, so I am at a loss here. The car has been meticulously taken care of since I've owned it and I have no idea what could be wrong. It's not throwing a single code or light, which makes this even more confusing. Any thoughts would be very much appreciated!

 

Sounds like the alternator. I had similar symptoms and also had a 'good' alternator check. The car will run fine for a while but eventually my tachometer lights would die on the road which was a little scary/fun, eventually it died completely but I was near home. To confirm I had a car battery gauge that plugged into the 12V outlet and gave the volts, if its consistently below 12V the battery is not charging correctly, it should always read 12.5 and 13-14 V while driving.

 

Would I not be getting a battery light if the alternator was not sufficiently charging the battery, or if the alternator was failing?

 

In my case the battery light did not come on until the car was just about dieing. I'd use the 12V outlet battery reader for the easiest test.

 

I checked it and it's actually measuring right at 15v.

 

I'm not sure what it could be sorry. My car didn't sputter, it may be something else.

 

I would second a failing alternator. Make sure the mounting bolts and the adjusting bolt for the alternator are tight as they are common on these cars to become loose and cause electrical issues. Also, many have had bad experiences with after-market reman alternators.