I've searched the forums, but I can't find my answer. I have another truck that I am swapping parts from, so here goes what I've swapped so far. All COPs, injectors, upper intake, oxygen sensors and new plugs. The tryck will run perfect until it gets up to operating and then all of a sudden a switch is flipped and it will go to missing, shuttering, whatever you want to call it. I was just curious what other sensors may be involved in closed loop operation and could cause this.
On these trucks they have a overheat protect mode. If the temp gets over a cetain temp it will go into protect mode. Even though the temp gauge doesnt say its hot it might be overheating, some of the gauges dont tell you when you are starting to overheat.
What you need to do is find out if you are overheating. You could put a manual gauge in or maybe take a infared termometer and read the temp of the coolant.
If it turns out that it is overheating, you need to-
-Check the fan clutch
-Change the coolant(esp. since it has overheated alot)
-Even better would be to flush the system
-Check to make sure radiator isnt blocked with dirt and crap
-See if thermostat is working
-Check water pump, it might not be circulating the coolant
If it is not overheating, maybe the temp. sending unit is telling the computer that it is overheating, when in reality it isnt.
Hope this helps, keep us posted.
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-1998 F-150 5.4l 2wd, with a worn out 3.55 LS.
-About to install 4.56s and rebuild the LS
-224,000+ miles w/ all orig. drivetrain
-No Muffler
The motor isn't running hot. After driving it for a while you can still put your hands on the heads and water crossover tube. When it is dead cold, it will drive great for about 3 miles then go to bucking. I do believe that it is going to to limp mode, I just have to find out why. There are two wires that lead under the intake. Maybe they connect to a temp sensor that has gone bad. If I dont find something soon, I'll take the intake off and see whats underneath.
Try posting this in the 97-03 section also. Maybe the temp sensor is faulty. I think its near the theromostat housing.
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-1998 F-150 5.4l 2wd, with a worn out 3.55 LS.
-About to install 4.56s and rebuild the LS
-224,000+ miles w/ all orig. drivetrain
-No Muffler
I had a town car do this, the PCM was bad. It would run full rich when in closed loop. Try swapping the PCM.
The cyl. head temp sensor is in the driver side head. If the gauge isn't going high, then I'd doubt that that is the problem. This is the temp that the PCm uses to go into overheat mode.
I took the entire top end off and put it back together. I didn't find anything wrong, but regapped the plugs from .045 (new) to .052 and used a lot of dielectric grease. I've driven it about eighty miles now with no problems. I hope it stays this way. Thanks for the input.
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