no shops can fix it
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New User
Joined: May 2002
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From: superior USA
no shops can fix it
alright....here is my problem. I have a 92 f-150 4x4 witha 4.9L Here is the problem. The truck studders horrible when under a load. BUT ONLY WHEN THE AIR TEMP IS WARM!!! Now during the cold months of dec/jan it runs fine except for some bad gas milliage. I have done a complete tune up of everything and the eec codes dont really help. The codes pretty much say the egr low voltage but I can plug the vaccum lines and unplug the computer line and the truck acts the same...it hesitates like its a fuel studder but the fuel pressure checks fine...one person said its the trainsmission but it does it also in the summer when you have it in park and rev the engine it will start doing it...I am stumped...thanks for any suggestion
Elder User
Joined: Sep 2004
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A bad oxygen sensor can cause the engine to run too lean once the truck warms up. Basically the truck runs fine until the CTS tells the computer the engine is warm enough to go into closed-loop mode. The computer listens to the oxygen sensor and it sort-of works, but the sensor is so old and slow that the engine gets leaned out too much, and you get the stumbles.
You can check this out further by running a KOER test. Warm the truck up, run the test, and see if the computer is happy with the reactions of the oxygen sensor. Or just replace the thing for $56.00
Check your grounds. Consider the possibility of a tired TFI module. Both can exhibit temperature sensitivity.
You can check this out further by running a KOER test. Warm the truck up, run the test, and see if the computer is happy with the reactions of the oxygen sensor. Or just replace the thing for $56.00
Check your grounds. Consider the possibility of a tired TFI module. Both can exhibit temperature sensitivity.
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