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Hi all,

I have my 2000 GSL and keep getting this code. I have had the intake cheked and is not leaking,Maf sensor is fine replaced all vacume hoses. The Fuel pressure is ok and still have no idea whats causing this code. Any help would be great.




Thanks
taurusmn1
 

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1128 is a coolant temp issue.. replace the thermostat and coolant.

Most use a timer to monitor how long it takes to reach operating temp from cold start.

Use a Hyundai thermostat only and gasket, mix coolant 50/50 in outside container and refill cooling system
 

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QUOTE (sbr711 @ May 11 2010, 07:16 PM) index.php?act=findpost&pid=321925
1128 is a coolant temp issue.. replace the thermostat and coolant.

Most use a timer to monitor how long it takes to reach operating temp from cold start.

Use a Hyundai thermostat only and gasket, mix coolant 50/50 in outside container and refill cooling system


well changed the thermo and coolant still got the code.
 

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QUOTE (taurusmn1 @ May 11 2010, 12:18 PM) index.php?act=findpost&pid=321816
Hi all,

I have my 2000 GSL and keep getting this code. I have had the intake cheked and is not leaking,Maf sensor is fine replaced all vacume hoses. The Fuel pressure is ok and still have no idea whats causing this code. Any help would be great.




Thanks
taurusmn1
I have researched some, and here is what I have found so far...

P0128 is the thermostat, not 1128!

1128 is the fuel air mixture:

Any unmetered air introduced into the engine can cause P1128 to set. Tips: Carefully check for vacuum leaks. Include all areas that might introduce unmetered air to the engine. Don't forget exhaust leaks before the O2 sensors. I have found that using propane while monitoring the oxygen sensor signal is a good way to locate small vacuum leaks when a smoke tester is not available.
The problem is that the MAF is incorrectly measuring the amount of air entering the engine. The vehicle power control module (PCM) calculates the required fuel based on the measured air flow. Since more air is entering the engine than the MAF is accounting for, the result is an overly lean condition and a code P1128.
1) Check and verify that fuel pressure is in specification. The fuel filter could be clogged up with crud.
2) If vacuum leak and fuel pressure checks are normal, check the air flow signal from the MAF sensor using a scan tool.
3) Verify that there are no vacuum leaks or any other faults that might cause a lean indication (low fuel pressure, exhaust leaks, faulty injectors, faulty secondary air system, etc.)
4) Use a scan tool to measure air flow at idle speed. The typical readings for a properly functioning MAF sensor will be 3.5 or more grams/sec at 800 rpm.
5) Replace the MAF sensor if the grams/sec reading is 2.0 or below at 800 rpm. It is sometimes possible to clean the MAF, but only use a cleaner that does not leave any residue on the MAF.
6) This is a good time to check the entire intake system for dirt or contamination. Make sure it is ALL clean. Use a cleaner that does not leave a residue (an electrical contact cleaner is a good example).
 

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Hello taurusmn1.

Without wishing to state the obvious, I'll presume that you have reset the ecu back to factory, if you have checked the vehicle properly and found no issue.

If you haven't, start the car and bring it to operating temperature. Stop the car and remove the ecu fuse from the underbonnet fuse box and replace after a few minutes.

Start the car again without touching the throttle and allow to idle for 2-3 minutes without touching the throttle. This will reset the fuel/air mix to factory economy settings.

If the issue disappears, then "Hooray!"...crisis averted.

If you still have issue then it should be fairly obvious that there is a detached or split hose to the intake plenum. A detached hose will be reasonably obvious.
A split hose maybe less so. The split may not be allowing additional air in until certain vacuum is reached. If you only get the check light after periods of harder driving, then it may be a split hose collapsing open under increased vacuum due to harder acceleration, if you follow me. Check around and under your hose clamps as well.

You don't state the condition of the injectors so I assume they're all OK as well.

Hope this is useful.

Cheers,

Andrew :thumbsup:
 

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Hey Andrew thanks for the info. I just changed the fuel filter and now its booging under load. I did not disconnesct any vacume lines and everything was reconnected properly with triple checks. just did what you said about the ECU fuse see what that does.
 

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well removed the ECU fuse still am getting the 1128 code. Guess I'll start from the beginning again and replace hoses and the intake gasket. yeah has anyone evr have their elantra pop out of third gear. mine does it so much i don't use it
 

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Hello again.

I have attached a copy of the hma.service diagnostic flowchart.

See if this is of any help.

Cheers,

Andrew
 

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