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1978 928 Runs rough and rich ext smell

Dear Porsche Techs!
I have a 1978 Porsche 928 5 speed manual. was stored and not run for 6 months. Now Runs rough and rich ext smell.
Alternator not working according to the gauge, but has new Bosch Alternator 1 year ago. Just had fresh oil change and coolant replaced.
Gretful for any help.
Thank you,
Kevin
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Old 07-13-2007, 07:07 PM
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Hi Kevin,

What part of SoCal? Maybe somebody is close enough to help.

I'm not a CIS guy, but what I hear is that old fuel goes nasty in the WUR, and that all trouble shooting begins with measuring the fuel pressure. Draining out the old fuel might be best, dumping in a bottle of Techron might work, or Stabil, with some fresh gas.

Does the "charge" light come on when you first turn the key? I don't know about the 78, but later cars use that bulb in the alternator exciter circuit, so charging is impaired if it burns out. Course it could just be loose belt.
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US 83 zinc metallic 5 spd, aka the nice car.
Euro 85 black, 5 spd, the fast rough track car maybe car.
Euro 84 red, AT, only car in garage in years, my parts car, soon to go last 5 years.
Old 07-13-2007, 07:59 PM
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The alt belt is tight, The alt light does not work when the key is turned on, The gauge does not work when it is running, I can tell it is Not charging because the head lights are a little dime.

I live in North coast San Diego.

Kevin
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2005 Husqvarna TC250

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Old 07-13-2007, 08:32 PM
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http://www.nichols.nu/tip692.htm

I don't know the 78 for sure, but it does sound like the bulb went out.

Gauges not working could just be pod grounds need cleaning. Best to approach with a systematic cleaning of all the ground points instead of one problem at a time though.
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US 83 zinc metallic 5 spd, aka the nice car.
Euro 85 black, 5 spd, the fast rough track car maybe car.
Euro 84 red, AT, only car in garage in years, my parts car, soon to go last 5 years.
Old 07-13-2007, 09:15 PM
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So if the went out that could stop it from charging?
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2005 Husqvarna TC250

1999 Porsche 986 Boxster 5 speed manual 90k. (as of April 2008)
Old 07-13-2007, 09:44 PM
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Quote:
Originally posted by RadioDjKev
So if the went out that could stop it from charging?
Basically yeah, at least in some model years. I just don't know for certain on the really early cars.

This link says its the Bosch alternators, and thats what you have right?
http://www.pelicanparts.com/techarticles/914_alternator_troubleshoot/914_alternator_troubleshoot.htm

Here is a link with some pictures.
http://www.stuttgartperformanceengineering.com/928DASHPROBLEM.html
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US 83 zinc metallic 5 spd, aka the nice car.
Euro 85 black, 5 spd, the fast rough track car maybe car.
Euro 84 red, AT, only car in garage in years, my parts car, soon to go last 5 years.

Last edited by Danglerb; 07-13-2007 at 11:27 PM..
Old 07-13-2007, 10:41 PM
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I wonder if my alternator not charging would also be related to the rough running and rich ext smell? engine ignition not getting enough power without alt? ( a charged battery not enought?

Thanks, Kevin
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Old 07-16-2007, 04:32 PM
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Not unless it was misfiring, which is past running rough. Most likely its the WUR and/or dirty injectors. A low battery can cause odd problems, so I would disconnect it and put a full charge on it before doing other stuff.
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US 83 zinc metallic 5 spd, aka the nice car.
Euro 85 black, 5 spd, the fast rough track car maybe car.
Euro 84 red, AT, only car in garage in years, my parts car, soon to go last 5 years.
Old 07-16-2007, 05:24 PM
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Yes it is misfiring. Battery is aslo old.
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1999 Porsche 986 Boxster 5 speed manual 90k. (as of April 2008)
Old 07-16-2007, 05:44 PM
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Misfire in a modern car is seriously bad due to the cats, and also rare since one of things EPA forced on manufacturers is a 50k mile warranty for all emissions related parts and that includes the ignition.

Check the voltage at the jump post in the front and directly at the battery, then disconnect and put a full charge on the battery and maybe just pop it out and test it at AutoZone etc.

Misfire and heavy rich with gas you can smell should NOT be run. Catalytic converters can dangerously overheat, and gas washing down cylinder walls removes the oil film.

I'd say you really need some hands on help from one of the other San Diegians.
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US 83 zinc metallic 5 spd, aka the nice car.
Euro 85 black, 5 spd, the fast rough track car maybe car.
Euro 84 red, AT, only car in garage in years, my parts car, soon to go last 5 years.
Old 07-16-2007, 07:23 PM
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I thing that my rough running engine is caused by the alternator not working. I think that even a fully charged battery will not let a 928 run smooth when the alternator is not charging.

I believe the electronic ignition runs off the alternator on these older 928's.

I found that my alternator is infact bad so I have ordered a new one.

Tomorrow I will find out for sure if this idea is correct or not..

Thanks for all your help.

Kevin
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2005 Husqvarna TC250

1999 Porsche 986 Boxster 5 speed manual 90k. (as of April 2008)
Old 07-18-2007, 09:50 PM
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Old style alternators put out little current at idle speed, essentially the cars run off the battery, and run just fine.

How was the alternator tested, given the known bad bulb in the exciter circuit?

Let us know how it turns out.
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US 83 zinc metallic 5 spd, aka the nice car.
Euro 85 black, 5 spd, the fast rough track car maybe car.
Euro 84 red, AT, only car in garage in years, my parts car, soon to go last 5 years.
Old 07-18-2007, 10:30 PM
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I checked the alt twice and it puts out nothing. Also had it benched checked at autozone. The bulb is good, as are all connections under the dash.
I already had 2 Porsche dealer techs tell me it needs the Alt to run normal.

Kevin
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2005 Husqvarna TC250

1999 Porsche 986 Boxster 5 speed manual 90k. (as of April 2008)
Old 07-18-2007, 11:19 PM
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I am getting very frustrated! Can anyone help!!!

My 928 still runs rough. I think it is something minor.

I installed a new Bosch Alternator today on my 1978 Porsche 928. Now I have a charging alt and 14.5 volts at the battery when running, 13 when not running, I also charged my batt fully. Now The alt light go's ON when the ignition is turned on, and it go's out when started.

However My volts gauge still stay's in the red??

And my engine still running rough and very stinky rich.
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2005 Husqvarna TC250

1999 Porsche 986 Boxster 5 speed manual 90k. (as of April 2008)
Old 07-19-2007, 10:28 PM
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Old 07-19-2007, 10:28 PM
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