Cold Hesitation
Senior User
Joined: Dec 2017
Posts: 109
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That almost sounds like you may have an Engine Coolant Temperature (ECT) sensor going out. The one that sends the signal to the computer has two wires (If I remember correctly it's just behind and a bit to the right of the distributor when standing at the front of the truck) and the one that sends the signal to the dash gauge has one wire. I read somewhere about a resistance test to see if the sensor is good but I can't find it and I don't have the manual that gives the test procedures for it. Sorry
I hope this can help a bit.
I hope this can help a bit.
It's sending an accurate reading when warmed up, but what is it sending on a cold start. If the ECT is telling the truck the engine is warm, when it's not. That would fit your symptoms.
Fleet Mechanic
Joined: Aug 2015
Posts: 1,829
Likes: 363
From: Candy Mountain
Just some thoughts to throw out there.
Vacuum leak in the TAD or TAB circuit during cold start / warm up operation.
Clogged/damaged AIR tubing or cross over pipe? (EEC expecting extra O2 and it isn't present, throwing off air fuel mixture?) I wouldn't expect to see a lean code as the EEC is ignoring the O2 sensor until the things warm up, at which point the AIR system switches to feeding the CAT.
This is assuming the AIR system is intact and functioning. Also if it isn't, the EEC would still command and expect extra O2 in the cylinder heads, but have no way to detect that it isn't there on cold start up, potentially causing problems.
Vacuum leak in the TAD or TAB circuit during cold start / warm up operation.
Clogged/damaged AIR tubing or cross over pipe? (EEC expecting extra O2 and it isn't present, throwing off air fuel mixture?) I wouldn't expect to see a lean code as the EEC is ignoring the O2 sensor until the things warm up, at which point the AIR system switches to feeding the CAT.
This is assuming the AIR system is intact and functioning. Also if it isn't, the EEC would still command and expect extra O2 in the cylinder heads, but have no way to detect that it isn't there on cold start up, potentially causing problems.
New User
Joined: May 2019
Posts: 9
Likes: 0
TPS codes are stored in memory.Also, PO removed the cat but left all the AIR equipment. yay...
Da_Lariat_Chariot do you have any misfiring throughout your rpm range as you drive?
Lead Driver
Joined: Oct 2016
Posts: 6,185
Likes: 633
From: Houston/Sugar Land
When you get to operating temp, does it still clear up and operate normally like you stated previously?
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