jwbeck17

Just something odd that I noticed with my 1989 928 S4. I almost never drive with the radio on, but I did yesterday. The OE radio was replaced by a later model Porsche CD player 1 DIN unit.

The odd thing I noticed is that when I accelerate the sound cuts out. Once I cease accelerating, all is normal and the music continues.

In most cars,that is a huge issue, but to be honest, if the radio cut out only at times so you can hear the engine roar, that's a unique benefit.

I haven't looked into this to much, but anyone experience this and have any suggestions?

ammonman

Failure. Strange, but definitely a failure.

Ducman82

sounds like it has a very crappy power supplied to it....

MainePorsche

Yep.
Power should be direct to battery to eliminate interference. Nice thick wire/cable, well insulated, employed. Your interference is not noisy, but appears to be in the extreme.

jwbeck17

I figured, but it is such an odd thing to do. I think I need to do some more testing on the unit, as the more I think about it, it could be other power issues. I was trying it with my iPhone connection, and I need to try it with the radio and CD. If only the Aux for the iPhone, then I suspect it could be drawing too much power.

Will play around and check.

Thanks!

auzivision

Sounds like a loose connection somewhere (power, signal source, or the output)... lots of variables that need to be eliminated.... following is a basic guide.

First being the sound source. Since it's an iPhone, could be a signal drop due to heavy RFI generated from ignition system or faulty connector. Post CD/Radio test if it's still dropping, need to figure out if the headunit is loosing power or is the output just dropping off.

Dese the display on the headunit go out when the sound drops? If not, then it's likely the output feeding the speakers. If yes, it's loosing power need to check connections.

If that's not it, then need to know if you are using an internal or external amp. If you don't know and one isn't visible, check under the amp cover between passenger seat and door jam... it's a carpeted cover that easily removed.

If you are running on an internal amp, need to check the connection harness/plug at the rear of the head unit. Should be able to get you hands on that simply by removing the carpeted section attached to the center console... just a few screws. Get you hand up behind the unit and wiggle wire to see if it drops or not.

If it's external, need to check both the back of the headunit and wherever the external amp resides.

My guess, knowing that iphone plugs can be slightly crooked when plugged in; hopefully, it's just a matter of ensuring the iphone connector is seated correctly. That would be the easy fix.

dr bob

Hmmm. Rare vacuum-operated radio, perhaps from an early car. Vacuum for the radio should be connected to the splitter by the brake booster, so that engine load doesn't affect the availabilty of vacuum so much. Perhaps the radio vacuum is leaking out from one of the HVAC actuators, detectable by a specific sucking sound in the center console at the time the radio output goes away.

I've noticed that many later cars have all the radio vacuum piping stuffed with strands of copper, perhaps to help maintain the shape of the flexible piping and keep it from collapsing.

geschwindig

Bob, that must be why I can't hear my stereo when I'm vacuuming the house...it sucks all the air out of the wires. And I thought is was age related hearing loss. Eh? What?

Ed Scherer

I just knew that sooner or later, someone would connect their WOT switch to the mute-for-phone-call input on their audio system.

WallyP

Feature. Reduces power consumption, so as to increase acceleration.

dr bob

"Bug" or "Feature", the eternal questions answered by expertz. The difference between a 'bug' and a 'feature' is how it's documented.

jwbeck17

Tested with the radio on and it kicked out during acceleration. All power to the unit shuts off then goes back on once acceleration is minimized.

Thinking it could be a connection issue, so I may need to pull the unit to check it out.

jorj7

Gee, Is the power to the radio coming from the same circuit as the AC. I think the AC will shut down under heavy engine load....

George
90 S4 Grand Prix White (Murf #5)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM)
http://928.jorj7.com

jwbeck17

Tested the AC and that runs fine under throttle, so it is just the radio unit. Basically, all power shuts off to the unit under throttle - no sound, screen shuts off, button lighting off. I checked and reseated the connections but the issue remains. There was some wire work that had been done as a few wires are clipped and sealed, however I would think if those cables were a problem, problems would be noticed right away. Not sure how to follow the power trail on this.

the flyin' scotsman

the radio should have 2 power connections; one for minimal load to keep programming and clock settings the other for when the unit is powered on and requires the greater amperage.

Does the clock lose time everytime it losses power? the answer will narrow the issue.