1997 Pontiac Bonneville multiple codes

Tiny
KLIVERGOOD
  • MEMBER
  • 1997 PONTIAC BONNEVILLE
  • 3.8L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 209 MILES
Originally the maf sensor went out, I purchased a new one and installed it also changed the thermostat at same time. The check engine light went off for a day then came on and car would have running issues on initial start up. Had codes read again and now throwing maf code, throttle positioning sensor code, temp sensor code and saying left bank running lean. Any help would be greatly appreciated!
Tuesday, March 3rd, 2015 AT 8:00 AM

9 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,182 POSTS
Have you checked for vacuum leaks? Have you checked fuel pump pressure?
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Tuesday, March 3rd, 2015 AT 8:41 AM
Tiny
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How can I check the fuel pump pressure? Also when car first starts the voltage and oil pressure guage are way low then they fly up and car idles correct again. Looked back through all the sensor wires I disconnected to get to thermostat and everything is connected correctly. Weird that 4 sensors go at once though.
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Tuesday, March 3rd, 2015 AT 8:58 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,182 POSTS
How long does it take for the voltage to increase after start-up?

As far as fuel pressure, here is a video to watch.

https://www.2carpros.com/articles/fuel-pump-pressure-and-regulator-test-video-all-cars
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Tuesday, March 3rd, 2015 AT 10:49 AM
Tiny
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Takes 3-5 seconds usually for the voltage to jump up and idle to return to normal
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Tuesday, March 3rd, 2015 AT 10:52 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Does it seem a low idle is causing the voltage increase to be delayed?
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Tuesday, March 3rd, 2015 AT 10:58 AM
Tiny
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Not 100% on that one. The voltage it low and it chugs and dies until voltage goes up then will stay running. It did go through a phaze of dying before it downshifted and volts dropped also then.
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Tuesday, March 3rd, 2015 AT 12:04 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,182 POSTS
Do me a favor. Take the vehicle to a nationally recognized parts store and have them both load test the battery and check the alt output. Most will do it for free.

To me, it sounds like there is an issue with one of the aforementioned items. If there isn't enough power to the electrical system, all kinds of things will go haywire.
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Wednesday, March 4th, 2015 AT 5:19 AM
Tiny
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Had battery and alt checked and both are fine. Now I'm lost on where to go next.
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Wednesday, March 4th, 2015 AT 12:49 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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That's good. Have you had a chance to check the fuel pump pressure? I am trying to eliminate things. Please bear with me.
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Thursday, March 5th, 2015 AT 6:33 PM

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