Engine Controls - Idle Dip/Fluctuation/MIL ON/DTC's Set

Condition





24 07 05 Feb. 2, 2007 2010583 Supersedes T. B. Group 24 number 04-03 dated July 12, 2004 due to inclusion into ElsaWeb, with Self Diagnosis Function update according to Base 10.01 update.

Engine, Fluctuating Idle or Idle Speed Too Low
Idle fluctuates or is too low at times, poor throttle response, engine bucking, cold start driving concerns, Malfunction Indicator lamp (MIL) ON.

Technical Background
May be caused by contaminants (dirt, oil) on interior surfaces of throttle valve control module -J338-.

Contaminants may cause bucking due to wrong airflow recognition.





DTC's which may be associated with condition:





In conjunction with the above listed DTCs, the following DTC's which may also be stored:

Production Solution
No production change required.

Service

NOTE: Always review and follow Cautions and Warnings listed in the Repair Manual regarding the use of the VAS 5051 and VAS 5052 during any road test.





- Connect the VAS 5051/5052 Diagnostic tool.
- Switch ignition ON.
- Select "Vehicle Self Diagnosis".





- Select Diagnosis Function "006 - Basic settings".





- Input "115" on keypad to select "Display group 115".
- Select "Q" button to confirm.
- Record results of Display group "115" at full load acceleration in gear and RPM range specified in table below.

Channel 3 value = Target value of boost pressure according to programmed map in ECM.

Channel 4 value = Actual existing value of boost pressure.

Values should not deviate from each other by more than 100mbar.

Road Test Requirements and Specifications
For 4 speed automatic, begin acceleration at 2000 RPM. Slowly depress throttle to full throttle. Avoid downshifting.
For all other transmissions, apply full throttle at approximately 1500 RPM.
For tiptronic use, depress throttle fully without activating kickdown switch.





Do not perform downhill.

If values deviate (consistently) more than 100 mbar, retest. If deviation still exists:
- Check for air leaks in charge air system using VAG 1687 diagnostic Tool as outlined in Technical Bulletin Instance 2010580.

If no leaks are found:
- Check charge air pressure system (see Repair Manual Group 21 - Turbocharger, G - Charger in ElsaWeb).

After road test, allow the warm engine to idle in warm surrounding.

Tip: Engine temperature must be a minimum of 80 degree C (176 degree F).





- Switch OFF ALL electrical accessories (A/C, seat heating, window defroster, etc.). Engine cooling fan must be OFF.
- Apply parking brake.
- Select the backward arrow on navigation bar.
- Input "003" on keypad to select "Display group 003".
- Select "Q" button to confirm.

Tip: RPM, Air mass, throttle valve angle and the Advance angle are displayed.

If Channel 2 indicates 0.0 g/s, then the MAF -G70- or it's wiring are faulty:
- Gently wiggle connector.

If value changes erratically, Connection is bad:
- Repair connection.

If Channel 3 value (throttle valve angle) is at 2% or higher:
- Clean throttle valve control module -J338- (see cleaning instructions below) thoroughly and readapt.
- Inspect crankcase ventilation system hoses.

If sludge or oil deposits are found inside hoses:
- Clean inside of hoses as necessary.





On all models:
- Remove suction jet pump for brake booster.

Tip: Suction jet pump shown is equipped on Jetta (radiator support at bottom of photo).

Tip: Suction jet pump shown is equipped on Passat.




- Inspect suction jet pump for blockage.

If blocked:
- Replace suction jet pump.

Continued for ALL vehicles:

Throttle valve control module -J338-, Cleaning instructions:
- Remove intake air hose from throttle valve control module.
- Inspect interior surface of throttle valve control module and throttle plate for dirt / oil film.

If interior of throttle valve control module is not dirty:
- Reinstall intake air hose.

Continue with diagnosis, (see appropriate Repair Manual group in ElsaWeb or VAS 5051/5052 Guided Fault Finding).

If interior of throttle valve control module is dirty / oily:

Tip: DO NOT replace throttle valve control module for this condition. Over a long period of time it is possible that dirt can accumulate on the inner surfaces.

- Clean interior surfaces of throttle valve control module (on both sides of throttle plate) with a soft clean cloth.

NOTE: It is not necessary to remove the throttle valve control module -J338- to clean.

For heavier deposits of dirt / oil film, apply Wynn'(R) X-Trend(R) V.I.C. Combustion Chamber Cleaner: Part No: 61510 (U.S.), Part No: 61512 (Can.) on a soft clean cloth then, clean interior surfaces using this cloth (one can of cleaner will do many vehicles, therefore it is considered shop supply).
- Reinstall intake air hose.
- Perform throttle valve control module adaptation (see Repair group 24 of appropriate Repair Manual in ElsaWeb or Guided Fault Finding). Recheck and save Display group 003, Channel 3 value with engine idling at operating temperature.

If throttle valve control module adaptation cannot be performed after several attempts (see Repair group 24 of appropriate Repair Manual in ElsaWeb for proper adaptation conditions):
- Spray a small quantity of Wynn's(R) X-Trend(R) into throttle valve.
- Gently push throttle valve closed completely and back open a few times.
- Reattempt adaptation. If throttle adaptation still cannot be performed:
- Replace throttle valve control module. If preceding steps did not determine a cause:
- Verify MAF operation using Technical Bulletin Instance 2010558 dated May 10, 2004.

Warranty
Information only.

Required Parts and Tools





No Special Tools required.