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Car starts and runs fine

Tiny
RONALEXANDER312
  • MEMBER
  • 1995 OLDSMOBILE 98
  • 139,500 MILES
Car starts and runs fine. Driving down the highway at 70 mph and will stall out. Was starting right back up but now isn't until I pull the wiring coupler off of the mass air flow sensor. Replaced yhe MAF sensor with no results. Am assuming it is a sensor of some sort since it will still run with MAF disconnected. Any ideas? Thanks!
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Monday, April 1st, 2013 AT 12:07 PM

9 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,328 POSTS
Have you checked the map sensor? Have you checked the fuel pump pressure?
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Monday, April 1st, 2013 AT 12:09 PM
Tiny
RONALEXANDER312
  • MEMBER
  • 6 POSTS
No I can hear the pump kick on and since it will run for about 20 miles before stalling and will run after I take the wires off the MAF that fuel pump is not the issue? Also cannot check codes as this vehicle Is obd 1 but has an Obd 2 connector. I did pull the idle air control and have cleaned it. Pulled the air intake and cleaned the honeycomb screen on the throttle body.
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Monday, April 1st, 2013 AT 12:21 PM
Tiny
RONALEXANDER312
  • MEMBER
  • 6 POSTS
Also have replaced some of the vaccum lines that I found were bad.
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Monday, April 1st, 2013 AT 12:25 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,328 POSTS
I have seen issues like this that were caused by a bad map sensor and a lazy fuel pump. The pump may not be keeping up with the demand at higher speeds.
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Monday, April 1st, 2013 AT 12:31 PM
Tiny
RONALEXANDER312
  • MEMBER
  • 6 POSTS
OK thanks will do some checking on these. Is there any test to check the MAP?
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Monday, April 1st, 2013 AT 12:41 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,328 POSTS
I always do an active test. While driving, my scanner provides real time information. I can watch how it reacts.
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Monday, April 1st, 2013 AT 12:45 PM
Tiny
RONALEXANDER312
  • MEMBER
  • 6 POSTS
Also car will start and run fine again after sitting over night. Reconnect the MAF but will also die while just driving around town at 35-40 mph. Seems something is heating up and then not operating properly? Will take it in for a fuel pressure check.
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+1
Monday, April 1st, 2013 AT 12:51 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,328 POSTS
You can test fuel pressure yourself. It's easy. There is a how to video and directions on our homepage under the DIY section.
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Monday, April 1st, 2013 AT 2:19 PM
Tiny
RONALEXANDER312
  • MEMBER
  • 6 POSTS
Fuel pressure at the rail is 45-46 kbs which I believe is within specs. Have changed plugs and wires with no change. TPS and idle air control valve are new also.
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Thursday, April 18th, 2013 AT 3:46 AM

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