Code p1128 weak mixture lose power on inclines engine light on melts spark plugs vehicle hyundia accent 2001

Code 170 means the computer can not adjust the fuel mixture by normal methods. Could be the O2 sensor, or a problem with the fuel injectors.

Hi there:
DTC P1128 is "Long Term Fuel Trim Too Lean"
This means the air/fuel mixture is leaner than the HO2S can compensate for.


This is most often caused by a vacuum leak. It can also be caused by a clogged fuel filter, unmetered air entering the air intake system, leaking exhaust system, canister purge system not operating or a weak fuel pump.


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No such code listed (P1128) for 2002 Accent

The code P1128 indicates there is a problem with the air flow sensor. It would be better if you change it.

take the vehicle to auto zone or parts source and they will scan it for free

Main causes of misfire would be loss of spark; the air/fuel mixture is too far out of balance to ignite; or loss of compression.

Loss of spark includes anything that prevents coil voltage from jumping the electrode gap at the end of the spark plug. Causes include worn, fouled or damaged spark plugs, bad wires or even a cracked distributor cap. A weak coil or excessive rotor gas inside a distributor would affect all cylinders, not just a single cylinder.

"Lean misfire" can occur when the air/fuel mixture is too lean (not enough gasoline in the mixture) to burn. This can be caused by a dirty, clogged or inoperative fuel injector; air leaks; or low fuel pressure because of a weak pump, restricted filter or leaky pressure regulator.

Loss of compression means the cylinder loses most of its air/fuel mixture before it can be ignited. The most likely causes here are a leaky (burned) exhaust valve or a blown head gasket. If two adjacent cylinders are misfiring, it's likely the head gasket between them has failed. Also, if an engine is overheating or losing coolant, it's likely the head gasket is the culprit.

You can isolate the weak cylinder by temporarily disconnecting each of the spark plug wires, one at a time, while the engine is idling. When there's no change in the idle speed, then you have pinpointed the weak cylinder.

Main causes of misfire would be loss of spark; the air/fuel mixture is too far out of balance to ignite; or loss of compression.

Loss of spark includes anything that prevents coil voltage from jumping the electrode gap at the end of the spark plug. Causes include worn, fouled or damaged spark plugs, bad wires or even a cracked distributor cap. A weak coil or excessive rotor gas inside a distributor would affect all cylinders, not just a single cylinder.

"Lean misfire" can occur when the air/fuel mixture is too lean (not enough gasoline in the mixture) to burn. This can be caused by a dirty, clogged or inoperative fuel injector; air leaks; or low fuel pressure because of a weak pump, restricted filter or leaky pressure regulator.

Loss of compression means the cylinder loses most of its air/fuel mixture before it can be ignited. The most likely causes here are a leaky (burned) exhaust valve or a blown head gasket. If two adjacent cylinders are misfiring, it's likely the head gasket between them has failed. Also, if an engine is overheating or losing coolant, it's likely the head gasket is the culprit.

You can isolate the weak cylinder by temporarily disconnecting each of the spark plug wires, one at a time, while the engine is idling. When there's no change in the idle speed, then you have pinpointed the weak cylinder.

sounds like you have some wires that have melted together somewhere that has gotten to hot.

P1128 - Long Term Fuel Trim Multiplicative System Too Lean.
The ECM will set a code and the MIL will turn on if the long-term fuel trim value goes from 10% to 15% lean for 30 seconds during two driving cycles when the following conditions are met:
1.- Engine loads exceeds 1.8 milliseconds.
2.- Engine coolant temp. is above 158F (70C).
3.- Canister purge system is not operating.
4.- Mass air flow is less than or equal to 5.5grams per second.
5.- Engine speed is below 1000RPM.

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The trouble code P1128 is for a faulty mass air flow sensor or MAP. This is a common problem with 1999-2000 Accents. There is air leakage within the unit and/or the hot wire in the unit is badly contaminated. A bad MAP will cause the vehicle to bog and loose power.