I'm having this problem with my radio; I've installed (actually some friends helped me) a custom head unit and amp. Occasionally when I start the car in cooler weather, the amp will sometimes lose enough power to turn off for a few seconds at a time. Usually when this happens I hear a click and 2-3 second whirrrrr from under the hood, and my dash dims/flickers a bit until the whir ends. Anyone have anything like this happen to them, or perhaps know what's going on? I'm stumped. :|

 

I'll think more about this later, but you don't by chance have a cap in the system do you? Ocassionally someone will set up a cap for their stereo, but put it on the switched side of the amp. When the car has been off for a few hours the cap drains...you go to start it up, and most of your juice is being used to refill the cap.

Not sure what the whirr could be without being there, but might it be the cooling fan? or one of the pumps?

Your starter draws quite a bit of juice, so when cold you may not have a lot of reserve to power the amp and radio.

 

The click and whirr is from the Air pump. When the engine is cold there is an air pump that runs to help the combustion of exaust in the catalitic converter. That pump might draw enough power to bring the voltage below your amps cut off level.

 

I'm really interested to see what you find out on this.

I'm having what looks like voltage inconsistency problems with my Clifford alarm. If I find anything out, I'll let you know.

Ted

 

OK just to clear things up. Caps or Capacitors are used to keep consistancy of voltage to your amps. They take less than a second to charge and do not discharge if they do you got sparks and a fire on your amp board.

You said that you had a custom head unit and amp put in.....were they truely cusom built or just custom installed. If all wires were run correctly you shouldnt have a problem. Direct batt. term connection good connectors etc. Sounds to me like there is a short somewhere in the wiring of the amp. Did you use a relay to kick on your amp? If not that might be your problem. That or the relay is your problem.

 

Pinky,

Caps discharge by themselves, there's no way around it (humans still can't create ideal caps). Parasitic resistance will slowly discharge them, although how fast depends on the grade of the cap. And charge time is dependent upon several factors, including capacitance, so 1 second may be correct for some caps, but WAY off base for others.

I haven't a clue how quality the audio caps are, but I wouldn't expect them to fully discharge after a day of nonuse...but you can never tell, and if a cap WAS going bad, the parasitic resistance may increase significantly, thereby speeding up the process to a few hours or minutes (I'd hate to see a 1F cap discharge in a few secs...I've melted screwdriver tips with 0.25F caps before). A bad cap may blow itself and nothing attached to it (especially in the case of high internal resistance). A high internal resistance would also show signs such as those pointed out (dimmed lights, etc.) as it's one huge load the battery/alternator were not designed for.

As a side note, many applications place bleeder resistors across the cap terminals to "bleed" off power when not in use. You'll find these in TVs and such where you don't want someone taking off the back cover, sticking their hand in there and turning into Rudolph.

I figured the whirring was a pump or fan of some kind, but not a clue as to which one. Good to know someone knew.

That all being said, my first line of attack would be along the lines of Pinky's thoughts...make sure the power connections aren't touching ground (also make sure no wires are chafing). If possible, put in a time-delay relay for the amp...give the alternator enough time to get the car running before adding more load to it (of course, as Pinky said, check the relay's health).

If these turn out to not be the problem, let us know and we'll slap our heads toegther again for more troubleshooting.

 

Wow, you guys certainly have turned up quite a few leads.. I'll try to answer these q's as best as possible:


MacGyver: No caps in the system. Plus the click-whir (air pump?) happens sporadically for the first 3-4 minutes of car operation, not just the couple of seconds I would expect the cap to take to charge. The radio (www.empeg.com) takes a few seconds to boot up anyway.

Pinky: The head unit is from empeg (www.empeg.com), I don't believe that it is the problem though as it stays online just fine through the click and whir. When voltage does drop for it, a battery icon flashes (I've tried using adapters with slightly less voltage and the unit will work, but the battery light will flash). We installed the unit and amp (and speakers) ourselves, though I don't know as much as my friends do. The amp is grounded to the chassis bolt right under where the spare tire resides. It is painted, though (the chassis), and we thought maybe filing the (insulating?) paint off may help. I have yet to do that. It is a direct battery connection, with a good gold Monster connector. I'm not sure about the relay question, I'll ask the guys who installed it.

MayGyver part 2: Re: The time-delay relay thing, I'm not sure if it'll help because it's for a random amount of time when I start my car.. around 5 minutes.. And occasionally, rarely (but it happens), even after 20 minutes of driving. It usually has a tendency to do it when I rev (or have been revving, eg highway driving) at 4-5 k then idle. I will check the ground on the amp this weekend, and see if I can find out more about the relay, since I don't really know off the top of my head.

 

Hmmm, the fact that it does this intermittently for several minutes bugs me...definitely rules out any caps (AND the fact that you don't have any ). It could be something as simple as a loose ground, or something more complicated like a bad internal amp protector.

Will it do this if the volume is extremely low? How about if you disconnect power to the amp?

It's difficult to troubleshoot over email, but try to limit the problem to a single unit (or at least figure out which units are NOT causing the problem).

 

Go back to your installer and have them check it out. Scrape under the ground to get bare metal.
The battery thing flashing is that on the radio or on the car its self? If its the car then bring it to the dealer you got bigger problems than a stereo thing.

Though it may be because of something to do with the stereo. Open circut staying on to drain the batterie.

Oh and MacGyver: The cap stays fully charged because its connected directly to the batterie of the car all the time. They are fully charged and ready to pop if you touch them any time after being charged/installed. Though they usually dont blow up!(thank god) We charge them and discharge them via a resistor.

 

Yeah, I'm pretty sure it's the amp, mainly because the unit comes on okay and works fine (the display is lit and working properly) from ignition to when I shut it off. Another reason to lead me to believe that it's the amp is that I'm getting some strange overload problem, and when I say that I mean that instead of music I get a terrible screeching and scraping sound out the speakers, which is volume independent. I can turn down or up the volume on the head unit without change to the volume of the noise. Also when it did it today at lunch I tried both hitting vtec and stepping on the brake. No change in sound when I hit the gas, but when I hit the brake the sound changed a little (I braked a couple times to verify).. So maybe it really is my amp either not grounded properly or just outright broken... Like I said, I'll ground it properly this weekend and check the relay and health of the wiring, my installer (a friend of mine) has some tools he says he can look at that stuff with. I'll let you know what the results are... hopefully it's the amp and not the car, the amp is a little easier to replace.