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Discussion Starter #1
So I have been searching looking for a check engine light library so that I can figure out what my P1128 code means.

Can someone please direct me?

-nate
 

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www.hmaservice.com I think thats a too rich/lean code and/or an 02 sensor code....
 

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That code is for your MAF. I used to get that alot then I bought a new MAF sensor and the problem went away. That sensor is comon to go bad.
 

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but before you go out and buy a new MAF... try cleaning yours.



also this code isn't specifically the MAF.. there are many contributing factors. and if I remember correctly.. thw webtech doesn't even mention the maf for this code.

[Edited by bh206 on Jan 16, 2006 8:03 PM]
 

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Discussion Starter #5
Thank you guys, I guess I will go on my way diagnosing everything!
 

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Had a P1128 and it was the MAF. Clean first then replace. Replace is a 5 min job but the D**n MAF cost $170 or so.

170 !!! but it looks like a cheap piece of crap plastic.
 

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Discussion Starter #7
Well guys, I have been driving my Accent ever since with this check engine code.

I ended up buying another 5spd Accent and swaped in the MAF from it. No difference.


The car has also developed a miss under throttle. Pretty much anything over 4k Rpm and it pops with a terrible miss.

I have done wires, plugs, and tried a different coil pack. Still the same miss.

Any ideas guys?
 

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From hmaservice.com:

P1128
Long Term Fuel Trim Multipicative System Too Lean

DESCRIPTION

The air/fuel control system, in addition to a number of sensors, includes the following components and systems:

Intake air system.
Exhaust system.
Evaporative emissions control system (includes purge control solenoid valve).
Fuel injectors.
Fuel pressure regulator.
Fuel pump.

For the air/fuel ratio to be within limits, all of the sensors, components and systems associated with the air/fuel control system must function within normal parameters.

FAILURE CONDITIONS

(FOR SHORT-TERM FUEL TRIM)
The ECM will set a code and the Malfunction Indicator Lamp (MIL) will turn on if the short-term fuel trim value goes 10% to 15% rich [for P1123] or if the short-term fuel trim additive value is less than 0.4 milliseconds, or 10% to 15% lean [for P1124] for 30 seconds during two driving cycles when the following conditions are met:

ECM is in closed loop operation.
Engine speed is below 1000 RPM.
Engine coolant temperature is above 158°F (70°C).
Canister purge system is not operating.
Mass air flow is less than 7.5 g/s [for P1123] or 5.5 g/s [for P1124].

(FOR LONG-TERM FUEL TRIM)
The ECM will set a code and the Malfunction Indicator Lamp (MIL) will turn on if the long-term multiplicative value is less than 77% for 30 seconds [for P1127] or if the long-term fuel trim value goes to 10% to 15% lean [for P1128] for 30 seconds during two driving cycles when the following conditions are met:

Engine load exceeds 1.8 milliseconds.
ECM is in closed loop operation [for P1127].
Engine coolant temperature is above 158°F (70°C).
Canister purge system is not operating.
Mass air flow is less than or 5.5 g/s.
Engine speed is below 1000 RPM [for P1128].





Running lean could be anything...
 

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Discussion Starter #11
Thank you, just to make the guy above happy :) I will check the 02 voltage with my meter to find out if its cycling or not.

I changed the plugs and most of my miss is gone.
 

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Discussion Starter #12
A follow up.

Took the MAS out cleaned with brake cleaner. Car would start very easily, but would not stay running.

Unplugged the sensor, car went into limp mode, all miss dissapeared and car is now running fine.

Will be looking for a mas from a junkyard in the mean time.
 

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I need a new MAF now too.

cleaning it bought me 5 more months.. it was at too rich before.. now it's too lean.


i've been running unplugged for 2 weeks now :O
 
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