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1990 Chevy Lumina Low vaccum

Tiny
DRUMMER1252
  • MEMBER
  • 1990 CHEVROLET LUMINA
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?
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Sunday, September 21st, 2008 AT 5:23 AM

2 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Your vacuum gauge reading does it look like below it represent a retarded ignition timing


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



Check your ignition timing and MAP sensor
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Sunday, September 21st, 2008 AT 5:34 AM
Tiny
DRUMMER1252
  • MEMBER
  • 2 POSTS
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.
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Sunday, September 21st, 2008 AT 7:49 AM

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