CEL Code Please Help
#1
08-01-2005 | 08:04 PM
Thread Starter
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1st Gear
Joined: Jan 2005
Posts: 105
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CEL Code Please Help
I got my CEL code..Please help me see what the problem is...
17536 P1128 long
term fuel trim mult. bank1 system too lean.
What is this??? Thanks
The scan can back, and my car is .33 pounds/min at 800rpm..Does any1 know how to convert this...Thanks
17536 P1128 long
term fuel trim mult. bank1 system too lean.
What is this??? Thanks
The scan can back, and my car is .33 pounds/min at 800rpm..Does any1 know how to convert this...Thanks
#2
08-01-2005 | 08:23 PM
Senior Member
Joined: Apr 2005
Posts: 887
From:
RE: CEL Code Please Help
1) 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.)
2) 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.
3) 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.
Diagnosis: One of the most common codes we see on OBD-II Volkswagens is P1128, a long-term, fuel trim lean code. 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.
1) Check and verify that fuel pressure is in specification.
2) If vacuum leak and fuel pressure checks are normal, check the air flow signal from the MAF sensor using a scan tool. The 2000 Jetta 2.0L AEG motor will typically idle at approximately 800 rpm. At 800 rpm the MAF should indicate grams/sec at 3.5 or above.
3) Snap accelerate the engine. The MAF will typically show a snap reading in excess of 60 grams/sec.
4) If the MAF grams/sec reading at idle is 2.5 to 3.0 or if the snap acceleration grams/sec is below 60, inspect the sensor for dirt or contamination. 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).
5) Once the sensor and intake are clean, recheck the grams/sec air flow. If it is now above 3.5 at idle and 60 on snap accel, the problem should be solved.
6) But if the MAF grams/sec at 800 rpm is below 2.5, or the snap accel grams/sec is below 50, the MAF may be out of calibration.
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.
Once again, try cleaning the MAF and rechecking the grams/sec air flow numbers. If they fall in line, the problem should be solved. However, if grams/sec are low after cleaning, it's time to replace a faulty MAF.
2) 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.
3) 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.
Diagnosis: One of the most common codes we see on OBD-II Volkswagens is P1128, a long-term, fuel trim lean code. 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.
1) Check and verify that fuel pressure is in specification.
2) If vacuum leak and fuel pressure checks are normal, check the air flow signal from the MAF sensor using a scan tool. The 2000 Jetta 2.0L AEG motor will typically idle at approximately 800 rpm. At 800 rpm the MAF should indicate grams/sec at 3.5 or above.
3) Snap accelerate the engine. The MAF will typically show a snap reading in excess of 60 grams/sec.
4) If the MAF grams/sec reading at idle is 2.5 to 3.0 or if the snap acceleration grams/sec is below 60, inspect the sensor for dirt or contamination. 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).
5) Once the sensor and intake are clean, recheck the grams/sec air flow. If it is now above 3.5 at idle and 60 on snap accel, the problem should be solved.
6) But if the MAF grams/sec at 800 rpm is below 2.5, or the snap accel grams/sec is below 50, the MAF may be out of calibration.
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.
Once again, try cleaning the MAF and rechecking the grams/sec air flow numbers. If they fall in line, the problem should be solved. However, if grams/sec are low after cleaning, it's time to replace a faulty MAF.
#5
08-04-2005 | 12:34 AM
Thread Starter
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1st Gear
Joined: Jan 2005
Posts: 105
From:
RE: CEL Code Please Help
The scan can back, and my car is .33 pounds/min at 800rpm..Does any1 know how to convert this...Thanks
ORIGINAL: InsaneHatter
2) 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.
2) 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.
#7
08-04-2005 | 10:35 AM
4th Gear
Joined: Jul 2004
Posts: 4,354
RE: CEL Code Please Help
As I recall, there are 454 grams in a pound x 0.33 is 151 grams/minute
divided by 60 seconds is 2.5 grams per second. That is on the lowish side. Check for vacuum leaks carefully and if none are found, and there are no leaks on the inlet tubes between the airbox and the throttle body, you probably need a new MAF.
You can get a reman one for about 90 dollars.
divided by 60 seconds is 2.5 grams per second. That is on the lowish side. Check for vacuum leaks carefully and if none are found, and there are no leaks on the inlet tubes between the airbox and the throttle body, you probably need a new MAF.
You can get a reman one for about 90 dollars.