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1995 Ford 150 5L 302. EFI , 166k miles- why does the engine die after warm up?
Steven here- thanks for previous suggestions. Symptoms: Trk was a work horse for 2 years. Dashboard engine light on & off for the 2 years. 1 month ago, engine died. Sputtered and spit like fuel issue; then died. THEN after cooling down, starts right up until warm then starts to miss, sputter/spit (no back fire) and dies.
Changed in-tank fuel pump, fuel relay, in-line fuel filter, thermostat on radiator, plugs & wires. Cleaned most connectors visible.
1. Truck starts, runs, now has a hesitation (popping noise- can heard almost like a backfire but similar to timing needing adjustment) BUT warms up and dies. Double checked correct plug wiring sequence from Distributor to plug is correct. (New sound/new issue)
2. Using Ford OBD 1 Code Reader (key on/engine off) I only get code 121 ‘Closed Throttle voltage higher or lower than expected.’
3. Used an old plug to test for spark. It sparked but not on every full crank of engine turn over.
I am at a loss for next steps. Any advise is welcomed. Steven
2. Using Ford OBD 1 Code Reader (key on/engine off) I only get code 121 ‘Closed Throttle voltage higher or lower than expected.’
I am at a loss for next steps. Any advise is welcomed. Steven
Don't know to much about the old Ford OBD1 system. However with this code, a quick and dirty test I think is to unplug and see what happens. If runs smoother, then I'd check the wiring and voltage at the TPS. Hope this helps.
I would unplug it, then start it up. Might run a bit rough since the TPS is a input sensor. However the computer should have a default strategy it will use. Maybe not as fancy new ones, but should still be there. The idea with it unplugged, if the engine stays running even when warmed up. We can narrow down what's getting hot that will cause the shutdown.
I replaced the TPS & cleaned the throttle body.
Can’t tell you why but all three (3) wires had any coating 1” up to the sensor.
(3 bare wires)
The Ford Code Reader OBD1 does NOT show code 121 (TPS) since it was replaced.
Good thing!
Next challenge is two (2) other codes indicate the PIP & EGR. I believe the EGR opens/closes by testing it unplugged and then plugged from start up.
Started great plugged. Trouble starting unplugged.
Still studying about the ICM relationship with TPS, EGR, PIP, & other components.
Open to suggestions.
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