Intermittent stalling/surging

Tiny
CJCURRY
  • MEMBER
  • 2000 BUICK LESABRE
  • 3.8L
  • V6
  • FWD
  • AUTOMATIC
  • 240,000 MILES
Randomly surges then stalls. The car fires right back up after it stalls. It is completely random. It does it on the highway, red lights, pulling out if a gas station, turning, idle. It runs and drives fine. But randomly the car starts to lurch (imagine rapidly depressing the gas pedal about 5 times in quick succession) then the RPMs drop and it dies. But if you put it in neutral while coasting after it dies, and turn the key, it fires right up. I've replaced the following parts

Pcv valve
Plugs/wires
Fuel filter
MAF sensor
MAP sensor
Radiator (previous problem)
Alternator (previous problem)

The car will not throw a code. First my problem started as the car would not start. Then I replaced pcv, filter, map, plugs and wires. It Started but would not stay running. After replacing the MAF it would stay running and now I'm to my current position. I'm leaning towards it being either

A. The crank sensor
B. The ICM.
C. COIL packs

I have fuel pressure so I am not sure. I am stumped and the mechanic the car has been with for a month's does not believe it is any of those. Does anyone know of this happening to others? Or have experienced this themselves?
Tuesday, March 28th, 2017 AT 8:10 PM

3 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Try cleaning throttle plate on both sides and iac hole clean around shaft well with choke cleaner that may be the problem. if it continues check fuel pressure with a gauge. auto parts rent it. see link
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
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Wednesday, March 29th, 2017 AT 7:04 AM
Tiny
CJCURRY
  • MEMBER
  • 2 POSTS
I've checked the fuel pressure. I've also cleaned the entire throttle body
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Wednesday, March 29th, 2017 AT 2:10 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
I really can't think of anything else other than fuel pressure it should be 48-55 psi and not drop more than 5 psi in 10 minutes after shutdown. Test is done with key on only. If it's leaking down then it may be a bad injector/ regulator / pinched line etc.I assume it has been scanned for codes the other thing maybe the mechanic should freeze frame it and check voltages as you may have a sensor low but not enough to set a code.
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Wednesday, March 29th, 2017 AT 3:11 PM

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