QuestionRich smelling exhaust upon start up and rough idle,since this is fuel injected 1.8 litter Porsche 914 there is little or no information on trouble shooting the system.
Is there a fuel air mixing valve that is adjustable or fixed. where is it located.
Car has always been hard to start mostly when hot.
cylinder head tepm gauge has been replace along with other screw in gauges.
any information will be gratly appreciated
AnswerAndy... Hello again. Now for an answer.
The symptoms you describe can often be attributed to one or more of the following:
ooo Engine misses at idle speed:
1. Spark plugs worn or not gapped properly
2, Faulty plug wires
3. Vacuum leaks
4. Uneven or low compression
5. L-jetronic system faults
ooo Engine lopes at idle:
1. Vacuum leaks
2. Air filter clogged
3. Fuel pump not delivering sufficient fuel
4. Leaking head gasket
5. Cam lobes worn
As for your question about fuel air mixing...the answer is:
"Fuel metering is effected by the intake air sensor. This is a device which senses the flow rate of the intake air by means of a stator flap in a chamber. As the flap swivels with increased airflow, a potentiometer which is coupled to it varies the voltage signal which is sent to the control unit........."
You can test the functionality of the air intake sensor. Think of it as the first place airflow will travel as it moves through and then exits the air filter. When you look down into the engine it'll be the smaller rectangular box adjacent to the air filter housing.
Attached to the "box" is a set of terminal wires which you'll disconnect...the terminals should be labelled by number....if not, they are 7,8,9,6,36, and 39 when looking at the terminal portion left on the air intake box, after the wires are disconnected. Terminals 7 and 8 are the farthest away from the air filter housing. Terminals 9 and 6 are the middle two. Connect an ohmmeter to terminals 9 and 6 and read for a resistance of 200 to 400 ohms. Then connect the ohmmeter to terminals 7 and 8 and read for a resistance of 120 to 400 ohms. If you don't get both readings within these guidelines the air intake sensor should be replaced.
The information in quotes above and most of the technical mumbo-jumbo about the air intake manual is directly from an excellent source you should have:
"Porsche 914 Automotive Repair Manual", published by Haynes. Its their product number 80025 (239) or 8W5-239. Your better local parts stores will carry this or can get it. You'll pay $18-22. You can often find good clean used ones at book sites on the web like Bookfinder .com and others. I think my wife found mine for $7.
If you have any follow-up questions, please don't hesitate.
Dave
