hiccup

[floater180]

has anyone have this happen to their st 4.6 ? I drove to an appointment and it took about 1hr, it's windy and the grille is pointing into the wind. start the truck, idles fine, as I accelerate out of the parking lot the motor surges. I'm thinking the coolant in the radiator is much cooler than what's in the engine and as it gets up to temp. the thermostat opens fast and it bucks because it thinks it's temp. is now cold and pumps in more fuel but the o2 sensors says it's hotter so it tries to adjust too fast and bucks. any thoughts? it only did this 3 times in about 4 years in the fall temps on hot, windy days.

 

[motormaggot]

3 times in 4 years? I don't think i'd worry too much over that. you could try to diag that forever and not come up with anything, you would need a scan tool to monitor coolant temp. does the temp gage indicate a problem? does the heat from heater get hot? also o2 sensors do not monitor temperature. they only monitor oxygen content of the exhaust, they do however have heaters in them to help them warm up. when the engine surges, does the vehicle itself surge? or does the engine rev up without vehicle acceleration? check engine light ever come on?

 

[floater180]

the truck will surge just not as bad as the motor. just not sure about this, I had a s10 pickup that surged and died, hit the key and away we go. on the 3rd or 4th time no start, it was the fuel pump, pia to change out by myself. these were in the same 2 weeks when the pump died. just checking to see if anyone has had this happen.