1991 Buick 3.8l start and stall hot

Tiny
J-ADAM12
  • MEMBER
  • 1991 BUICK REGAL
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 104,000 MILES
1991 Buick Regal Custom, 3.8l Starts and stalls after hot soak. Second attmpt after hot soak will start normally. IAC, PCM (but not memcal) replaced. All pids appear normal. On second start attempt MAF base reading higher? Runs very well after PCM replacement. Stumped? No codes stored.
Saturday, January 8th, 2011 AT 2:22 AM

8 Replies

Tiny
DAVE'S BIG BACKYARD!
  • MECHANIC
  • 262 POSTS
Ign module.
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Saturday, January 8th, 2011 AT 3:18 AM
Tiny
J-ADAM12
  • MEMBER
  • 5 POSTS
No loss of spark, fuel injector pulses or fuel pressure. PCM eliminated stall while warming up and stall after throttle touched during warmup.
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Saturday, January 8th, 2011 AT 3:33 AM
Tiny
DAVE'S BIG BACKYARD!
  • MECHANIC
  • 262 POSTS
Run a compresson check. And check well for vac leaks.
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Saturday, January 8th, 2011 AT 4:01 AM
Tiny
J-ADAM12
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  • 5 POSTS
Hmmm, have not done a compression test! Checked for vacuum leaks both wet and with propane. IAC count 14 with TPS of 0.42vdc on hot idle.
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Saturday, January 8th, 2011 AT 4:09 AM
Tiny
DAVE'S BIG BACKYARD!
  • MECHANIC
  • 262 POSTS
Can you keep it running at all when it does this?
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Saturday, January 8th, 2011 AT 4:19 AM
Tiny
J-ADAM12
  • MEMBER
  • 5 POSTS
Only if you have the throttle cracked. Otherwise the next startup is normal. Only happens on first start after hot soak. Cold start is normal.
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Saturday, January 8th, 2011 AT 4:35 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Get some choke cleaner and clean the throttle plateon both sides. Clean the iac hole there as well they get gunked up with oil and cause this. Your car will starthard after doing thishowever. Make sure to connect the duct so the maf wil work. If it continues thengive the maf a small rap with scredriver handle. If the car quits running the maf is probably bad. If it doesn't effect it, then cross a&b on the aldl and look up your codes on the diagnostic under OBD1. Also check the resistance of the crank sensor as thesee will go bad and not give a code.
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Monday, January 10th, 2011 AT 12:06 AM
Tiny
J-ADAM12
  • MEMBER
  • 5 POSTS
Problem solved and one to remember. Cheap PCV Valve had been installed and was soaking the intake in oil. Oil had also fouled the injectors. New quality PCV Valve and a injector clean restored normal starting.
Thanks to everyone. The throttle body had been cleaned and MAF was cleaned (fouled by oil and dirt). This one was driving me crazy. Good for 8 hot restarts so far.
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Monday, January 10th, 2011 AT 3:21 AM

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