 L-Jet not idling when HOT, Doesn't like 32C / 90F outside temps |
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| nihil44 |
 Feb 15 2018, 01:17 AM
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#1
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Member  Group: Members Posts: 157 Joined: 28-January 12 From: Brisbane, Australia Member No.: 14,058 Region Association: None 
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My '74 1.8 normally runs beautifully but with our present 90 degree F ambient temps it runs hot and won't idle.
Temp gauge is just short of the red zone. (Next time I will get NHS to put numbers on the gauges.) Thermostat works - checked with hot air gun. Flaps are opening Warm air guides installed Tried enriching idle mixture by screwing in air bypass screw to max - no effect Would appreciate help from the brains trust Thanks David Brisbane, Australia |
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| nihil44 |
Feb 16 2018, 12:27 AM
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#2
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Member Group: Members Posts: 157 Joined: 28-January 12 From: Brisbane, Australia Member No.: 14,058 Region Association: None
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Got it.
Thanks Will check on the car. I am a little suspicious of the CHT sensor. Will also check that after a hot run Thanks again  |
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| djway |
Feb 16 2018, 01:27 AM
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#3
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Senior Member Group: Members Posts: 787 Joined: 16-October 15 From: Riverside Member No.: 19,266 Region Association: Southern California |
QUOTE(nihil44 @ Feb 15 2018, 10:27 PM)  Got it. Thanks Will check on the car. I am a little suspicious of the CHT sensor. Will also check that after a hot run Thanks again This may help Bosch L-Jetronic Fuel Injection System Basics Ambient Temperature Sensor (S5) (aka. air intake temperature) Function: Measures intake air temperature (air density). Location & Operation: In the air meter, a NTC thermistor (temperature sensitive resistor) sends a signal to the injection ECU. Air density and air flow are used to calculate air mass and control fuel injection duration. Cooler air is denser, and requires a richer mixture than warm air. Failure: Causes poor fuel mileage. Test: For resistance rise & voltage drop at ECU pin 27 (ARM 04-23) when using a hot air blower versus ambient temperature (cold=high voltage, low ohms / hot=low voltage, high ohms / @20°C = 2.6 kohms, 2.6 VDC). Or use an ohmmeter to measure the resistance across the two pins of the temperature sensor. Temperature F° Resistance Ohms 14 7,000-12,000 68 2,000-3,000 122 700-1,000 176 200-400 185+ Less than 200 Temperature Sensor Temperature sensor resistance The resistance between ECU plug terminals 13 and 17 (ground) should read 2-3 kOhms at 68 F/20 C. At 14 F/-10 C 7-12 kOhms, at 176 F/80 C 250-400 Ohms. • Meter reads infinite resistance: Check temperature sensor directly at terminals on sensor. If sensor resistance is ok, replace cables. If tester shows 0 Ohms (continuity) at sensor terminals, replace sensor. • Meter reads 0 Ohm (continuity): Pull plug from sensor. If meter at ECU plug then reads infinite, replace sensor. If not, replace cables. |
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Posts in this topic
nihil44 L-Jet not idling when HOT Feb 15 2018, 01:17 AM
falcor75 Check that your fuel pressure still is ok, if the ... Feb 15 2018, 02:21 AM malcolm2 I assume you are talking about oil temp. I also a... Feb 15 2018, 07:51 AM nihil44 I haven't checked fuel pressure but I have rel... Feb 15 2018, 02:14 PM djway In the AFM box there is an air density/temp sensor... Feb 15 2018, 02:25 PM nihil44 Thanks djway,
That diagnosis fits the scenario be... Feb 15 2018, 03:50 PM nihil44 Got an old AFM and looked inside but couldn't ... Feb 15 2018, 06:33 PM
nihil44 Temp Gauge Feb 15 2018, 06:35 PM
djway
Got an old AFM and looked inside but couldn't... Feb 15 2018, 10:16 PM Valy Please check that the auxiliary air valve closes w... Feb 16 2018, 01:31 AM nihil44 Looks like it's fixed
A very talented friend ... Feb 17 2018, 01:07 AM |
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