Codes 121 and 336, rough idle?

1994 FORD RANGER
109,000 MILES • 2.4L • 4 CYL • 2WD • MANUAL
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GOGOJUICE6
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  • 76 POSTS
Hey, guys, after replacing the whole fuel system, (among the TPS, twice, EGR valve ,1 EGR solenoid twice, etc.) I'm still having idling problems. Not to mention smoke test, negative, comp test was good. I'm getting 121 and 336 codes (closed throttle volts high and EGR volts, high), constant 5.04 V, Signal 1.3 V at TPS. EGR solenoid KOER is 14.5 V. I'm wondering if it's volt regulator burning the sensors.
I'm banging my head (hard) against the walls on this one...
Thanks so much for all your help...
Al
Oct 25, 2022 at 4:00 AM
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STRAILER
  • ✓Experienced Mechanic
  • 55,267 POSTS
Yes, the alternator could be creating AC voltage because it has a diode that is out. Check this guide out which shows you how to test for AC voltage. Also, what were your compression readings?

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Please go over this guide and report back.
Oct 26, 2022 at 2:43 AM
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GOGOJUICE6
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hey, Ken, cylinder 1 has 160 PSI. #2 170. #3 165. #4 175. Checked for ACV, 0. still idling rough. Noticed exhaust pipes too hot. painted them with VHT and paint was burned. getting an infra thermometer....
Thanks for all your help.... greatly appreciated...
Al.
Oct 27, 2022 at 8:54 AM (Merged)
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