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| 85 GT running rich? (Page 2/3) |
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olejoedad
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JAN 12, 05:14 PM
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Did you check the timing?
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fierofool
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JAN 12, 08:03 PM
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| quote | Originally posted by GravityKat:
That is the one I bought! I never fully spliced everything so I’m gonna go see if I can swap them.
Update: I looked and the thread size is different on the one they sold me. It has the oval head but it doesnt fit in the hole for the spot under the silver coolant cap :/
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The proper one will have a brass end that sits in the coolant flow. The other temp sensor with an oval head that's acttually a 4th temperature sensor goes into the air filter canister. It has a mesh type shield over it's sensor.
The ECM temp sensor under the thermostat housing actually screws into a threaded reducer, so it may appear to have different thread sizes.
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fierobear
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JAN 13, 02:59 AM
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| quote | Originally posted by fierofool:
The one on the head doesn't affect the runability of the engine. It is only for the gauge and temp light. The one underneath the thermostat housing, just above the water pump sends engine temperature to the ECM and that controls the fuel injectors. If that sensor is reading cold, it will dump more fuel into the engine.
If the sensor they sold you for the head required cutting and splicing on a new harness end, they sold you the one that should be installed above the water pump. The gauge sensor has a round plastic head with a slot in the side. The ECM temperature sensor has an oval plastic head. |
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A LOT of extra fuel. And the car will run like s***. I had a failed coolant temp sensor, and on my scanner the ECM was seeing a reported temperature of -40dF. Cold air is denser, so...lots of extra fuel and lousy gas mileage.
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fierofool
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JAN 13, 09:16 AM
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Same thing happened on my 87 and it was sudden while sitting at a traffic light. I made it to a friends shop and the scanner said it was -28*. It actually ran better when I disconnected it to go to the parts store to get another.
You can see the reducer for the Coolant Temperature Sensor in this illustration.
 [This message has been edited by fierofool (edited 01-13-2020).]
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GravityKat
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JAN 14, 08:05 PM
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I disconnected the correct one and it’s still giving me trouble. I still have to see what will happen if I put the new one in there. I just haven’t been able to get the reducer off the old one.
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fierofool
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JAN 14, 08:22 PM
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Yeah, it won't run great, but I think the ECM goes to a default mode if the sensor is unplugged. Not quite so rich.
The reducers are standard items at hardware or plumbing supply stores. If a vice and pipe wrench or 2 pipe wrenches won't sepadrate them just take along the new sensor to match the female thread and the old reducer to match the male thread. They are both standard pipe threads. Assemble them with some plumbers pipe dope. A brass reducer might be a good replacement piece.[This message has been edited by fierofool (edited 01-14-2020).]
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GravityKat
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JAN 15, 08:36 PM
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| quote | Originally posted by fierofool:
Yeah, it won't run great, but I think the ECM goes to a default mode if the sensor is unplugged. Not quite so rich.
The reducers are standard items at hardware or plumbing supply stores. If a vice and pipe wrench or 2 pipe wrenches won't sepadrate them just take along the new sensor to match the female thread and the old reducer to match the male thread. They are both standard pipe threads. Assemble them with some plumbers pipe dope. A brass reducer might be a good replacement piece.
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Would the EGR valve be causing this problem you think? The previous owner told me a long time ago that there was something wrong with it but I brushed it off. Would it be causing the engine to run this rich.
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fierofool
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JAN 16, 09:42 AM
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I don't think so. Usually, a defective EGR valve will cause a high idle. About the only defect they can have is a leaky diaphragm or gasket.
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fierobear
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JAN 16, 02:23 PM
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| quote | Originally posted by fierofool:
Yeah, it won't run great, but I think the ECM goes to a default mode if the sensor is unplugged. Not quite so rich.
The reducers are standard items at hardware or plumbing supply stores. If a vice and pipe wrench or 2 pipe wrenches won't sepadrate them just take along the new sensor to match the female thread and the old reducer to match the male thread. They are both standard pipe threads. Assemble them with some plumbers pipe dope. A brass reducer might be a good replacement piece.
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If you have a vice and the right size impact deep socket on the old sensor, you should be able to remove the fitting. You might need a "torque multiplier" - using a pipe slipped over the ratchet or preferably a breaker bar.
I use teflon pipe tape on the threads.
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fierofool
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JAN 20, 05:20 PM
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Did you ever get this sorted out?
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