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rockaria's Avatar
 
Join Date: Apr 2002
Location: Southwest USA
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Quick Question 2: how does the L-Jet "Temperature sensor I" work

Hello,

Thanks for the help in the last question. My next one is simply how does the L-Jet Temerature sensor I work? (The one in the AFM on a 1975 1.8 L-jet.)

It seems to cut off injection when hotter and inject more when colder on starting. Is this true? It seems that when my car sits in the 110 southwest heat it does not want to fire the injectors. (I have spark, fuel pressure, and compression, just the injectors not fireing on startup) Once it does start it runs perfectly.

Any thoughts.

Also, does Pelican offer 914 Camps? You know, spend a day with an expert and your car and ask all the questions you want. I would spend money for that! Though this forum rocks and does a great job at it, but I think I could come up with litterally hundereds of questions!

Thanks,
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Christopher A. Landt
rockaria@rockaria.com

1979 911sc
1973 914 2.0
Old 08-01-2002, 01:41 PM
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The sensor is an NTC thermistor--that is, a resistor whose resistance drops off the hotter it gets. It should tell the ECU to shorten the injection pulse when the intake air is warm, and lengthen the pulse when the intake air is cold.

The effect it should have on the mixture is pretty small. It should never tell the ECU not to fire the injectors.

Note that many (all?) 74 1.8s did not have this sensor.

For non-working injectors, I'd try the grounds and the resistor pack, and then check the "extra" wire that goes to the (-) terminal of the coil. That wire tells the ECU when to inject fuel.

--DD
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A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling
Old 08-01-2002, 01:51 PM
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Thanks, That is what I was looking for.

I checked both the wire and resistor pack and they seem fine. The wild part is the fact that once it does start when hot, it runs perfectly. If it is hot from the sun (Not driving) is when the problem exists. When it is hot from the sun the key won't start it, but my remote starter button will. (This is after sitting in 110 degrees not running, engine temp 110, and the starter cranks just fine.)

Strange?
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Christopher A. Landt
rockaria@rockaria.com

1979 911sc
1973 914 2.0

Last edited by rockaria; 08-01-2002 at 02:05 PM..
Old 08-01-2002, 02:02 PM
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I had the wierdest problem that I could not figure out for a few days. Car would not start, but when it did it ran fine. Non of the injectors would fire, but it would crank. My first thought was the fuel injection. I spent days checking everything. If I could get it started it ran great. I traced it back to the ignition switch. One of the contacts was intermintant. It would still crank fine with spark, but no injectors. Once I fixed this it starts perfect every time. I noticed that if the contact was not made that the voltage guage in the center console stayed at zero. If I wiggled the key around till the guage moved it would start instantly. Something to check. Dave
Old 08-01-2002, 07:57 PM
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Holly S__T That was it!

I am having trouble with the ignition switch a little. It was new, but did not fit correctly. I notice it does have trouble and when cranking it does turn off the dash lights. MAN! and it will start with my remote starter, but that is when the key is in position 2 and working fine... It all makes sense now!

OH MAN! THANK YOU SO MUCH! I was tearing down everything. I even ripped my FI Elbow taking the air box out so much. Any one have an extra 75 L-JEt elbow they don't need?

Thanks!
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Christopher A. Landt
rockaria@rockaria.com

1979 911sc
1973 914 2.0
Old 08-02-2002, 05:41 AM
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