1990 Chevy Lumina Low vaccum

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DRUMMER1252
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Engine Performance problem
1990 Chevy Lumina 6 cyl Front Wheel Drive Automatic 1.6K miles

1990 Chevy Lumina, 3.1 V6, auto trans. NO CODES display. Vaccum test gauge reads "retarted timeing" at idle. I cannot find a vacume leak. Car hesitates when fuel pedel is first pushed, then accelerates fine. I changed throttle position sensor, no change. I unplugged the Knock sensor, makes no change in reading on vaccum gauge and sets no chk eng code while unplugged. I was originally checking vaccum to transmition modulator valve for cold 1st to 2ond shift problem. Timming chane??? Bad computer or connection???
Sep 20, 2008 at 10:23 PM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,988 POSTS
Your vacuum gauge reading does it look like below it represent a retarded ignition timing


https://images.2carpros.com/forum/automotive_pictures/12900_vac12_1.gif

Check your ignition timing and MAP sensor
Sep 20, 2008 at 10:34 PM
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DRUMMER1252
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No. The gauge is steady about 15. The vaccum guage has a portion marked "timming retarded." The car has no timing marks on crank balencer. Also no distributer.
Sep 21, 2008 at 12:49 AM
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