Rough going '78 911SC
09-22-2002, 05:44 PM
#1
Cruisin'
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Join Date: Jul 2002
Location: Drammen, Norway
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Rough going '78 911SC
I'm a newbie to CIS troubleshooting and wondered if anyone had 2 cents on this... 
The motor will not idle very good. It's very rough going and i can't find the source to the problem... When cold it will idle rough but does not die out. When warm it dies when trying to idle. New plugs, plugwire-set, rotor and distributor cap have been installed. It helped some, but still rough going. Fuel injectors should be in a good condition (have replaced one and the others seem to be fine as i looked compared and checked the old sparkplugs). I checked the ignition timing and it seemed correct. Lever inside fuel distributor seem to operate fine and the sensorplate seem to stop where it should (at the narrowest point).
There's good power at 2500 and upwards and the engine runs much better there than at lower revs. This makes me also assume that the system deliver enough fuel (?). No backfires anymore. But there has been some (where at the air-box should i check for possible cracks??). Could it be that the fuel distributor gets a faulty "signal" from the Control Pressure regulator? I noticed a little split at the end of the hose mounting into the fuel distributor (coming from the cpr) - will inspect that one tomorrow. Tried adjusting the CO some - both leaner and richer - did not do the trick either so i set it back to where it was. The aux. air regulator, could that one be interesting to check any further? Or am i totally lost here... <img src="graemlins/c.gif" border="0" alt="[ouch]" />
~eJensen~
btw, pardon my english - i'm from Norway...
The motor will not idle very good. It's very rough going and i can't find the source to the problem... When cold it will idle rough but does not die out. When warm it dies when trying to idle. New plugs, plugwire-set, rotor and distributor cap have been installed. It helped some, but still rough going. Fuel injectors should be in a good condition (have replaced one and the others seem to be fine as i looked compared and checked the old sparkplugs). I checked the ignition timing and it seemed correct. Lever inside fuel distributor seem to operate fine and the sensorplate seem to stop where it should (at the narrowest point).
There's good power at 2500 and upwards and the engine runs much better there than at lower revs. This makes me also assume that the system deliver enough fuel (?). No backfires anymore. But there has been some (where at the air-box should i check for possible cracks??). Could it be that the fuel distributor gets a faulty "signal" from the Control Pressure regulator? I noticed a little split at the end of the hose mounting into the fuel distributor (coming from the cpr) - will inspect that one tomorrow. Tried adjusting the CO some - both leaner and richer - did not do the trick either so i set it back to where it was. The aux. air regulator, could that one be interesting to check any further? Or am i totally lost here... <img src="graemlins/c.gif" border="0" alt="[ouch]" />
~eJensen~
btw, pardon my english - i'm from Norway...
09-22-2002, 06:46 PM
#2
Instructor
You need to have a fuel system pressure check done, and check for vacumn leeks.
The fuel pressure test is outlined in many Bosch Fuel Injection books. They are available by mail, web, or in a book store. You can pay someone to do it, or you can purchase a tester yourself, for about $80 US.
For vacumn leaks, you need to spray carbureator cleaner around any gaskets and hoses(1 at a time). If the idle increases, you have found your leak.
Also make sure your timing is adjusted properly, and that the CO mixture is correclty set, with a gas tester.
Good Luck!
The fuel pressure test is outlined in many Bosch Fuel Injection books. They are available by mail, web, or in a book store. You can pay someone to do it, or you can purchase a tester yourself, for about $80 US.
For vacumn leaks, you need to spray carbureator cleaner around any gaskets and hoses(1 at a time). If the idle increases, you have found your leak.
Also make sure your timing is adjusted properly, and that the CO mixture is correclty set, with a gas tester.
Good Luck!
