Zetec w/mtx, part throttle surge

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Sony Focus
Posts: 11
Joined: Mon May 11, 2009 4:11 pm

Hey people-I could use your help. My foci isn't running like it should. The thing that I noticed is; the Baro is reading is showing on a scan tool @ around 82-83kpa. My understanding is that is what the reading would be in say Denver CO. 5500ft above sea level. I am wondering if there is a method to check the MAF in it's calculation of the baro. I don't have a problem replacing the MAF, I am wondering if there could be any underlying issue causing the baro to be so far off. The Minneapolis area I believe is around 800ft above sea level. Thanks in advance for any help!
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PBZX3
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Location: Lakeville, MN

The ZETEC uses a MAF Mass Air Flow sensor not a MAP Mass Air Pressure senor. I don't think it cares about barometrci pressure only air flow.

I would lean towards the DPFE. If it's the DPFE the surging will be more noticable at a constant throttle position in 1st or 2nd gear.
Paul

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Sony Focus
Posts: 11
Joined: Mon May 11, 2009 4:11 pm

PBZX3 wrote:The ZETEC uses a MAF Mass Air Flow sensor not a MAP Mass Air Pressure senor. I don't think it cares about barometrci pressure only air flow.

I would lean towards the DPFE. If it's the DPFE the surging will be more noticable at a constant throttle position in 1st or 2nd gear.
Yes, no MAP (Manifold Absolute Pressure) on Zetec.
I know the Baro is a function of the MAF. Thanks for the reply
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FocusMech.73155
Posts: 334
Joined: Sat Mar 15, 2008 2:31 pm
Car: '07 Focus ST (supertight)
Location: North St. Paul, MN

The MAF does measure the baro reading and if it is off you will get lack of power and even sometimes misfires. If you remove the sensor and inspect the hot wire. The hot wire should be clean of any foreign materials. You are not susposed to clean them, however I have cleaned them at work before and they didn't have a problem. Just use a little carb cleaner and let it air dry. If it is clean and it reads out of wack, replace it.
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Sony Focus
Posts: 11
Joined: Mon May 11, 2009 4:11 pm

FocusMech.73155 wrote:The MAF does measure the baro reading and if it is off you will get lack of power and even sometimes misfires. If you remove the sensor and inspect the hot wire. The hot wire should be clean of any foreign materials. You are not susposed to clean them, however I have cleaned them at work before and they didn't have a problem. Just use a little carb cleaner and let it air dry. If it is clean and it reads out of wack, replace it.
Thanks Focus Mech, I appreciate it.
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focinite
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Car: black cvp vroom vroom
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id say IAC if its surging. 8)
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FocusMech.73155
Posts: 334
Joined: Sat Mar 15, 2008 2:31 pm
Car: '07 Focus ST (supertight)
Location: North St. Paul, MN

one thing to add is if you replace your maf sensor, the baro reading will eventually correct itself, but it will take a while. when you replace it you should re-set you KAM. That will allow the maf to re-learn the baro quicker
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Jeffescortlx
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focinite wrote:id say IAC if its surging. 8)
The IAC valve can only allow metered air in, no reason for it to surge at part throttle.

My guess is to stick with a MAF problem, or possibly the O2 sensor is on the way out.
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Sony Focus
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Joined: Mon May 11, 2009 4:11 pm

Focus Mech, I sent you a pm. Sony Focus-Thanks
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Sony Focus
Posts: 11
Joined: Mon May 11, 2009 4:11 pm

Sent you a pm Focus Mech. Thanks
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focinite
Master of Phonemic orthography
Posts: 3718
Joined: Sat Jul 02, 2005 8:32 pm
Car: black cvp vroom vroom
Location: anoka mn

Jeffescortlx wrote:
focinite wrote:id say IAC if its surging. 8)
The IAC valve can only allow metered air in, no reason for it to surge at part throttle.

My guess is to stick with a MAF problem, or possibly the O2 sensor is on the way out.
i have had an iac cause isuses at part throttle, the plunger came away from the shaft and fluttered acting like a loose intake tube or a unmetered air leak. also on the tuaruses with the 3.0 ohv this is or was a common issue.but for the most part the maf is to blame, i just wanted to throw in a nother possible area to look, but its alwasy sumptin simple stewbid. 8)
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Sony Focus
Posts: 11
Joined: Mon May 11, 2009 4:11 pm

focinite wrote:
Jeffescortlx wrote:
focinite wrote:id say IAC if its surging. 8)
The IAC valve can only allow metered air in, no reason for it to surge at part throttle.

My guess is to stick with a MAF problem, or possibly the O2 sensor is on the way out.
i have had an iac cause isuses at part throttle, the plunger came away from the shaft and fluttered acting like a loose intake tube or a unmetered air leak. also on the tuaruses with the 3.0 ohv this is or was a common issue.but for the most part the maf is to blame, i just wanted to throw in a nother possible area to look, but its alwasy sumptin simple stewbid. 8)
Thanks Gents! SF
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