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TOPIC: !978 cold start up IDLE/RUN PROBLEM

!978 cold start up IDLE/RUN PROBLEM 07 Mar 2010 08:22 #127


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My "78, 928 starts but idles very low and doesnot rev and spits or pops sometimes when attempting to rev up. Can drive around the block but engine seems to be in later ecu models limp mode until after 15 minutes when eng warms and full rev power, driveability,etc.returns. I had a new warm up regulator on the shelf so replaced it -same problem. Fuel pressures are fine when warm up because it runs well then. Bosch fuel injection book doesnot mention this situation specifically in trouble shooting. Has anyone encountered and solved this problem?

Best regards, Greg
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!978 cold start up IDLE/RUN PROBLEM 03 Apr 2010 15:44 #155


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Your symptoms are unusual for a car of your year model. If your car was equipped with the later L-jet system then I'd be suspecting the "temp II" sensor as a possible fault. Have you checked your vacuum?
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!978 cold start up IDLE/RUN PROBLEM 03 Apr 2010 15:50 #156


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This would be CIS, correct?

Have you reviewed the fuel distributor?

I saw one that had problems when cold, and under load, because the filter screen in the fuel distributor line was clogged. Might be unrelated, but often it isn't recognized that there is a filter there.
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!978 cold start up IDLE/RUN PROBLEM 04 Apr 2010 11:54 #157


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Isolated faulty auxiliary air valve--replaced with used one from 928 intl. This particular problem went away. Thanks for responses. Greg
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