Note the brushes on the internal regulator in the photos in the link. These are a wear item.

http://www.bimmerparts.com/ShopByVeh...ulator&mode=PA

 

I took the old Valero internal regulator off of my alternator before sending it in as a core. I don't think the 3.2 and SC use the same internal regulator, otherwise I'd let you have it.

 

When I get back to San Luis this Friday I will take out the alternator and see if I have an internal or external regulator. Would you guys take the alternator into an auto shop and have them test it? Are there any recommendations for good non-China alternators?

iceman, if I fully charge the battery, then drive it up my hill, what am I looking for while doing so? Should I measure the voltage at the battery again while it is idling? I find it interesting the battery had plenty of charge to turn the engine over and over, yet not enough charge to make a good spark. I guess the ignition system uses a lot of power.

I just realized the alternator light is the light on the dash with the battery picture. I thought that was the battery light! Sometimes I make no sense. It lights up when I turn the ignition on and goes out when the car has started.

- Andrew

 

i was just trying to isolate wether the low battery was causing your misfiring. Sounds like they may be unrelated from your description. The ignition actually does not take very much relative power. if on a fully charged battery you are still mising and backfiring then that is not causing your issue.

you don't have to take the alternator out to find out if it is internal or external . if your external is gone .. then it is internal.
If the light goes out while idling your alternator is putting out at least 12v. it should be in the order of 13.5 Measure it again a idle and post here. if you rev it a little it should go up higher , don't remember the numbers off the top of my head though .. maybe 13.8- 14 volts ?

 

I have taken 2 alternators to be tested. I took an Audi alternator with 200,000 miles to an Autozone and they told me the voltage regulator was fine and the diode pack was blown. I replaced the voltage regulator because the brushes were worn and drove the car another 50,000 miles. I took a VW alternator to an Advance Auto and they told me the alternator was not switching off correctly. The car was a Diesel with a stripped flywheel I had just bought. It wasn't until after I replaced the voltage regulator that I found out the alternator had been disconnected at the starter. There was nothing wrong with the alternator. The people at the parts stores just tell you whatever the machine that is designed to sell more reman alternators says. You may have luck with a good electrical shop but remember that the machines make mistakes and so do the people. They told me my spare RX-7 battery was not any good because the machine said so. I have been using it for 2.5 years and it has never died.

I would check your voltages and brushes and make a decision accordingly. I think this is something you can diagnose yourself.

 

I have no experience with alternators but I am always eager to learn and fix things myself. Can anyone point me to a good article on checking an alternator to determine which components should be replaced? Are these parts something an auto parts store would carry? I searched for alternator brushes at pelican and came up empty.

 

The brushes are built into the voltage regulator. I think the voltage regulator (with built in brushes) is the only easily replaceable part. There is one gentleman on here that has rewound his own alternators and is probably the most knowledgeable. I have purchased voltage regulators at parts stores before but I did not see them listed for an '82 911. Remember you need to look it up for the newer car if you have been updated. I bought mine from www.germanautoparts.com for $52.51 and it is a Valeo listed for 82-89 and I believe it was made in France.

 

I took the fan out with the help of my homemade fan removal tool, and discovered the brushes on the voltage regulator were worn down, one so much it wasn't making contact with the part on the shaft. I replaced it with a new regulator, and now have 14.1- 14.4 volts at the battery while the engine is running. The car no longer dies, and the battery is staying charged, however I am still experiencing the sputtering/small backfiring out of the tailpipe whenever I step moderately on the accelerator. The sound is more pronounced in a higher gear around 2-3K rpms where load can be placed on the engine without the rpms changing too quickly. It may be my imagination, but the sputtering seems to have decreased a slight amount.

Does anyone have any ideas on what to do next? I was thinking of checking the timing, and if that checks out OK I might change the coil.

Any ideas would be much appreciated,

- Andrew

 

I'd check timing advance for sure. Could be fuel mixture. Probably not the coil. 14+ volts is too high. You might want to check that again with a different multimeter.

I didn't realize you were in SLO. If you are stuck, take your 911 to Smith Volvo on I think Higuera and Santa Maria (?). Look for the repair shop next door, or for the parts shop called "Strasse". Ask for Gabe. I forget the owner's name, but I think it's "Guy". He can test stuff on your car for you including voltage. If you need parts, Gabe can help you with anything. But do NOT go throwing money at it. The CIS cars can be murder if you take that approach.

 

i wonder if the mechanical advance in your dizzy is working .

 

I took the car out for about 7 miles today, and it seemed to have good power, but the sputtering was still there. After parking it in my garage for about an hour, I was going to check the timing advance, but couldn't get the car to start. It would turn over and over, and sometimes would catch and rev up to 1k, then die. I took the air filter off and with the ignition on pushed up on the airflow sensor, and could not hear the buzzing sound (fuel pump?) that is supposed to sound letting you know fuel is flowing. This leads me to believe I am now dealing with a fuel delivery issue in addition to the sputtering. Is that buzzing sound when the airflow sensor is lifted coming from the fuel pump, or ...?

- Andrew

 

The buzz you should hear is fuel shooting through the injectors - the injectors buzz. If no buzz then there is not enough fuel pressure at the injectors.

I just got an '80 SC that was sitting for two years...It's running very much as you describe. Starts and idles great, but under load it sputters and "blats" out the exhaust and feels like it is being held back, almost like a rev limiter. But it will cruz at any speed just fine. Only when I try to accelerate it sounds awful.

I have searched and searched and seems like a fairly common problem, but the ideas are all over the place, from ignition to fuel related.

1. A post confirmed that a very clogged fuel filter caused similar problems to ours. Now that you dont have fuel pressure at your injectors - you should look at this.

Please post any results you may find in your quest.

 

Hey Dave

The buzz is back. Turns out the previous owner didn't understand that there are different amp rated fuses for different components in the fuse box. The 16 amp in the fuel pump fuse slot is supposed to be a 25 amp and was shorting out. I checked and cleaned all the fuses and contacts, and replaced a few with the correct ratings. A little bit later today I'll check the timing and go out for a spin. I'll post what happens.

Also a friend of mine who knows old cars couldn't figure out what was going on, he said it sounded like an exhaust leak. I can't find any evidence of a leak on my car but you ought to check yours just in case.

 

I checked the timing, it was OK. The timing advance at 5k rpm is in spec. While driving the car around, I noticed when putting load on the engine in 5th gear and around 1k RPM no sputtering could be heard. The sputtering is most pronounced from 2400 on up. In the Bentley manual it says to disconnect the vacuum hose, but I can't find any vacuum hose or hose connector leading to the distributor. While revving the engine quickly I am getting a bit of backfiring, and the spark in the plugs is yellow. I think I may try a new coil and 02 sensor to see if anything improves.

Any suggestions appreciated

- Andrew

 

This is not the right picture but you should have a vacuum line very close to what is on this distributor, if not look around and see if it has popped off and if it has I'd bet thats the root of your problem.