'95 F150 Drivability Issue

[polarbear]

'95 F150 4X4, 5.0L, 4AOD, 49-state emissions.

The good: starts up fine, shifts in and out of gears fine, shifts up and down no problems (on the levels).

The bad:

1. "Check Engine" light on almost all the time.
2. On long steep hills (and we've got plenty) truck doesn't want to downshift unless it's almost floorboarded. When you go that deep into the throttle, "check engine" light goes off and truck will downshift. "Check engine" light comes back on as soon as you back off of the throttle. Truck upshifts and downshifts normally on the levels though.
3. No fast idle when started cold- or at any other time. Truck never stalls, but I'm used to a high-idle cycle when starting cold or when the A/C is turned on. This truck does neither.

I suspect #2 and #3 are related?

 

[polarbear]

bump for the morning crew.

 

[blacksnapon]

Just from the symptoms, I'd go with an egr/vacuum issue. WOT there will be little to no vacuum. You might get the dtcs read then you could have a general direction to start looking.

 

[polarbear]

Thanks- I'll keep you posted.

 

[polarbear]

Update- reader sez the TPS (throttle position sensor) isn't. Voltage in, no voltage out. We've got one coming, and we'll go from there.

 

[blacksnapon]

Update- reader sez the TPS (throttle position sensor) isn't. Voltage in, no voltage out. We've got one coming, and we'll go from there.

The TP sensor is a good bet for all of your problems.

 

[polarbear]

Update: New TPS is in, "check engine light" is off. Kid sez it drives like a completely different truck- I'll give it a road test later on tonight. He's bringing the g/f over for dinner (hmmm.....).