awilli6

Hey guys. Got a powered woofer installed the other day. Car ran fine after. Got home and it wouldn’t crank. Swapped out relays and fuses and it finally cranked. All relays seemed ok. Clicked when switch turned on. The only thing I saw was the defrost relay was missing the cover. When I pushed it, even with the car off, the AC would blow. I changed it and don’t have the same issue with the new one.

Car are will not start. Is it possible the fuel pump as went? I’m pretty good at bolt on, replacement parts but horrible at diagnosis. Where should I start. 89S4

awilli6

Any thoughts

Mrmerlin

disconnect the new electrical parts,
charge the battery then try to start the car

FredR

So you bolt on a powered woofer- you did not specify the power rating but let me guess- does 500 watts sound like a good number?

Did you check the volt meter while you were driving along busting your eardrums? Did it show 12 volts or less by any chance?

You live in Memphis- presumably it gets pretty hot down there so let's assume the a/c was on. You did not specify whether you were driving during the day or nighttime- can we assume night time?

You get back home presumably you stopped the motor and shortly afterwards you tried to start it and... nothing other than a clicking sound. That presumably was your starter motor solenoid continuously cutting in and dropping out when there was not enough juice in the battery to energise the stater motor.

You have a 120 amp stock alternator that can barely feed the amperage needed on a stock [non ghetto blaster] 928S4 when the lights and a/c are on. The alternator system does not produce full output until it reaches about 3k rpms then it levels off. Were you driving at 3k rpms or driving at a nice sedate 2k rpms enjoying the music?

Sounds to me that either you have a knackered battery or the additional [40?] amps needed to drive the woofer were just too much for your system. Recharge the battery [if you can], and with the new toy giving it some, take a look at the voltmeter. If the voltmeter shows noticeably less than 13.5 volts with lights, a/c and Aerosmith blasting out you will be draining down the battery whilst running.

If the system was on the limit before the new addition, taking 40 amps out of a fully charged battery in good condition will flatten it in 90 minutes or less. How long was your drive?

The numbers are for guidance and to help you understand what might have been going on.

My late 90S4 had an expensive after market audio system fitted.and although impressive, the electrical system really struggled with lights and a/c in operation and the music track from Top Gun blaring out. Not so with the pissy little system on my current 928.

If my assumptions hold true, you may well need an alternator upgrade from the likes of Greg or Carl to feed your powered woofer.

awilli6

Thanks for the info guys. I’m from Memphis but moved to the DC area with the military a couple of years ago. Still very hot here. I did drive with the air on but it was daylight so no lights. When I picked the car up, it cranked fine without hesitation after several stops. I was trying to find a shop to recharge R12. The last place I stopped, was where it would no longer turn over. I get more than a clicking sound. It cranks but won’t turn over. I’ll try to disconnect the woofer, charge the battery and see what happens. Unfortunately my voltage does not read on the dash. It does when first cranked but then the needle goes flat. I’ve checked with voltmeter and get about 13.5. That was pre woofer install. I’ll follow your instructions and report back.

ash

Wisconsin Joe

This statement is self contradicting.

It's a bit pedantic, but if you want help, you need to post a bit clearer.

"Clicking sound" - When the battery doesn't have enough power to make the starter motor rotate the engine. What's happening is that the solenoid is energizing, but once it tries to move the starter motor & engine, the voltage drops to the point that the solenoid doesn't stay closed. Once it opens, the voltage recovers enough to energize the solenoid. "Click-click-click-click." Sometimes called the 'solenoid death rattle'. The engine itself does not rotate.
Or, there can be a clicking sound coming from individual relays as they open and close. Far less loud than the solenoid & they come from the CE panel.

"Cranking" - When the battery has enough power to energize the solenoid and rotate the starter motor. So the motor is rotating too. "Ruhr, ruhr, ruhr, ruhr."
"Turning over" - When the engine is turning because the starter motor is making it rotate. See above "cranking". They are the same thing.

"Firing" - When the engine actually makes itself run. This can be 'sputtering', where only one or two cylinders are actually igniting and the motor won't run on it's own. Or it can be all cylinders igniting and the motor running. "Ruhr, ruhr, ruhr, ruhr, vroom."

Ok, enough criticism of your language. Now an actual suggestion to diagnose the problem:

Since your dash volt meter doesn't work, grab a hand held meter.

Check voltage at the battery and at the jump post.

See what the voltage is with key off, key on and while cranking (you will need a helper to check it when cranking).

If I understand your post correctly, the car is cranking (turning over), but not firing.

I'm going to guess that your battery is a bit low and you don't have enough voltage to get it to fire. Anything under 10v cranking is a problem.

dr bob

Many accessory audio system components (Read: amps and powered subs) connect directly to the battery. They then depend on a separate signal to turn on when the car starts or the head unit is powered on. If the installer isn't careful, or more often is lazy/careless, the amp trigger lead will get connected to something on all the time, so the amplifier is continuously draining the battery even while the engine is stopped.

Procedure:

-- Take it back to the installer and explain the symptoms, and ask him/her to recheck connections for the new components to make sure they are seeing the right signals for turn-on. If the amp/sub works with the key off, it's wired wrong and will drain the battery quickly even if you don't have the haed unit turned on.

-- Take a hard look at all the connections at the battery positive and the ground strap. One or both of those were disconnected while the new equipment was installed. A loose cable or ground strap connection (either end) risks the erratic cranking/starting symptoms you describe.

----

Historically for me and from my perceptions anyway, a serious portion of electrical problems on our cars start off with less than stellar audio and cellphone-related work done by folks who can't read or don't have access to the wiring diagrams. Just poke into CE panel connections and wiring with a test light until you find one that goes on and off with the key, rather than finding the existing turn-on circuit for the radio or the existing antenna-trigger lead from the head unit. During installation one hopes that they disconnect the battery as a first step, since having the hatch open and interior lights on quickly starts raining the battery. Or they drained it and fast-charged it when trying to get stuff to work. The list of possible screw-ups is long and extinguished.

awilli6

Thanks fellas. I do need to be more clear. The car tries to “crank” but wouldn’t fire. The clicking was the relays that I was checking. The powered woofer has a delay once the car is running. The radio comes on but a few seconds pass before the bass actually kicks in. I disconnected the batter and put it on a charger. Before I began charging, I disconnected the powered woofer from the + battery terminal and the car still would not fire. The battery was showing it needed to be charged so I’m hoping it will fire once the battery is charged without the woofer.

How many amps amps should I be looking for an alternator to put out? The high output ones from the 928 vendors are steep. I didn’t see a price for Greg Brown’s rendition. You know what they say, if you have to ask, you can’t afford it.

If if that proves to be the problem, I’ll bite the bullet. Is there any other option for high output alternator that won’t break the bank but will be a direct fit?

FredR

Ash,

Once the battery is drawn down significantly, driving the starter motor sees the volts drop noticeably and at some point the computer/ignition systems appear to cease working. At least we now better understand what is actually happening so kindly advise whether the car will fire up once you get it charged and leave the woofer thing disconnected until you get the 928 operational once more.

For purposes of completeness what is the power rating of the new woofer- I could only guess what it might be.

In answer to the point you raised I am not aware of any other options for an increased alternator output other than the options I mentioned. What you need to consider is that the folks who do these kind of things have to spend time and effort developing & testing the package for what is a relatively small market segment and trying to recover their input costs is always going to be difficult to say the least. If it was that easy then you would simply have to purchase alternator model xxx-yyy and as far as I know that is just not the case so I doubt you will get the answer you were hoping for but....?

awilli6

Hi Fred,

The woofer is 500 watts. I know all things aren't equal, but my 87 S4 ran the same setup without an ungraded alternator. I'll put the battery back in this evening without the woofer and see what happens. If it fires, i'll re-try the woofer and see if it draws the batter back down. If so, it looks like i'll be ordering an upgraded alternator. Roger is my go to and he has told me he has them in stock. Thanks for all of you guys' time and advice.

Ash

FredR

Ash,

If nothing else I get a point or two for guessing the rating correctly!

You should also consider there may be other factors in play. If the engine harness is original I can pretty much guarantee it is shot by now. Take a careful look at the condition of the 16mm2 cable entering the hot post - it is probably a very manky looking brown- it should be fire engine red. The insulation will probably be shot and hanging on to the cable it is insulting by wing and prayer. If the cable flexes at all it will probably crack and/or drop off in chunks. Worst hit will probably be adjacent to the alternator and where they fasten to the starter motor. Remember the cables that run from the battery compartment, through the starter motor, on to the alternator, then the hot post and ultimately to the power the central electrics are permanently live. If the insulation fails and grounds you have a very expensive welding machine on your hands. The cores inside the cables form the starter motor to the hot post have a tendency to fail with the insulation in poor condition and then the conductors corrode and create resistance to current flow. If you can and if you are up for it, kindly take a picture of the cables entering the 14 pin connector and the hot post.

Where did you take the power supply for the woofer from?

awilli6

The woofer is being supplied directly from the battery + side. The wiring harness to the alternator and 14 pin connector is new. Got one of Sean’s last year. I do give you credit for the guess on amperage but my selection of music was Earth, Wind, & Fire. Had not made it to Aerosmith yet. I’m gonna look at all grounds and put the battery back and see what happens. Hopefully the alternator can handle it with freshly cleaned grounds. Negative batter cable and engine ground wire are less than a year old also.

FredR

So you have covered all the bases on the wiring side- excellent. With that wire connected directly to the battery it will help to some extent but 500 watts at 12 volts is 40 amps. Superimpose that on a 120 amp alternator that when new was already a bit marginal and...?

As we Brits [the real masters of the universe] know only fellow Brits [Stones, the Who, etc etc] can define rock or so I thought until I went to the inaugural F1 race at Abu Dhabi back in 2009 when Aerosmith were the race night stage act. Had not been to a rock concert since I left university. What a showman Steve Tyler was [probably still is] and te concert was truly amazing but- I reckon he and Keith Richards must be the most worn out human beings on the planet! In car terms they must have done over a million miles without a rebore!

awilli6

Hooked the recharged battery back up. Would not fire. I tried to jumpstart with the SUV and it still wouldn’t fire. It cranks strong but will not fire. What now? I’ve replaced the fuel pump relay. I checked all fuses.

Rich9928p

There are two more relays to replace; LH and EZF. It takes all three for the engine to run.

Rich
928 OC Membership Chairman
1993 928 GTS Cover Girl
1987 928 S4
1979 928 5-speed rescue cover girl too
1979 928 Euro 5-liter track beast