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Chasing a temperature related misfire by Joe 1320
Started on: 08-13-2014 07:57 PM
Replies: 4 (68 views)
Last post by: Joe 1320 on 08-14-2014 06:31 PM
Joe 1320
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From: Sebring, Florida
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Report this Post08-13-2014 07:57 PM Click Here to See the Profile for Joe 1320Click Here to visit Joe 1320's HomePageClick Here to Email Joe 1320Send a Private Message to Joe 1320Edit/Delete MessageReply w/QuoteDirect Link to This Post
In an 87 SE 2.8, 24k miles..... The car starts and runs perfectly in most every situation. I can drive it as long as I want with no issues, however...... Shutting down the car and letting it heal soak and a subsequent start up, it runs rough until the temps stabilize. Then it cleans out and runs perfect again. Typical when I stop for gas. in that short time of a fill up, after start ip it runs rough for 20-30 seconds and then clears up. It seems like the longer I let it heat soak, the longer it runs crappy after the start up unless I let it cool down some. then it works perfect. The only time it acts up when running is when stuck in traffic in the hot summer with the a/c on and the temps getting high. Traffic starts moving, airflow picks up and again once temps drop it runs perfect. My best guess would be the coolant temp sensor located up by the fill neck. Any other thoughts?
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phonedawgz
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Report this Post08-14-2014 12:00 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Leaking fuel injector. Dribbles fuel into the intake manifold. Makes it start hard when you go to restart it after a short turn off. Fuel pressure remains in the fuel rail as it is supposed to. But fuel should not leak past the injector.

Leave it shut off long enough and the fuel evaporates. But try to restart it when it has only been off for a short time and the fuel is still there.

How to see if this is what is indeed happening? - Start it up and run it a bit. Turn it off and look down the throttle body. There shouldn't be any fuel dribbling down the throttle body throat.

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thesameguy
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Report this Post08-14-2014 01:45 AM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Leaking fuel injector seems likely, however my Alfa would do exactly the same thing (and sometimes even "flood") and it was an unhappy coolant temperature sensor.
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85 SE VIN 9
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Report this Post08-14-2014 07:34 AM Click Here to See the Profile for 85 SE VIN 9Click Here to Email 85 SE VIN 9Send a Private Message to 85 SE VIN 9Edit/Delete MessageReply w/QuoteDirect Link to This Post
Might just be vapor lock, fuel getting too hot in the lines. Try insulating the lines where they get closest to the manifold. Today's fuel boils at a lower temperature due to the 10% that's not gasoline.
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Joe 1320
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Report this Post08-14-2014 06:31 PM Click Here to See the Profile for Joe 1320Click Here to visit Joe 1320's HomePageClick Here to Email Joe 1320Send a Private Message to Joe 1320Edit/Delete MessageReply w/QuoteDirect Link to This Post
Just to clarify,

1. there is no hard starting condition. Fires right up, just when it's hot it runs a little rough until temps stabilize.

2. Can't look down a throttle body on a 2.8 and witness an injector leaking...... Different fuel system from a 2.5

3. Inclined to think either fuel is getting heated or coolant temp Sensor is getting wonky.

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