Diagnostic Strategies

Driveability Complaints

AllDATA Editor Note: Hard Starting, rough running, stumbling on acceleration and/or poor idle or stalling may be caused by excessive carbon build up on the intake valves. After the elimination of other possible causes for these symptoms have not remedied the problem, a good look at the intake valves may indicate the need for removal of excessive carbon build-up. See the TSB excerpts below.


GROUP 04 Tools and Equipment
Bulletin Number 04 12 86 (1225)

This Service Information Bulletin supersedes S.I. 04 01 85 (974). It contains new information concerning the availability of the Carbon Blaster.

SUBJECT: Carbon Blaster




To eliminate idle and driveability problems caused by carbon build-up on the intake valve, a Carbon Blaster (components illustrated below) has been available since March 15, 1985.

1 Carbon blaster assembly
2 Compressed air hose
3 Return hose
4 Discharge hose
5 Spark plug adapter
6 Hold-down nuts
7 BMW cleaning adapter

The Carbon Blaster can be used two different ways:

1. Blasting intake valve stems and intake valve ports.

2. Blasting intake valve stems, intake valve ports and combustion chambers.

This machine "Blasts" special sized and graded walnut shells through an adjustable nozzle built into the cleaning adapter that attaches to the intake port.

After completing Blast cycle the loose carbon particles and used cleaning materials are removed by compressed air through the return hose.

NOTE: By using the Carbon Blaster, cylinder head removal will no longer be necessary to clean carbon from the valves. Refer to S.I. 11 14 84 (936).
At this time, the stocks of carbon blasters are exhausted. However, new stocks of Carbon Blasters will become available during the middle of July 1986 through the BMW Parts Distribution Centers.


GROUP 13 Fuel Systems
Bulletin Number 13 13 86 (1211)

SUBJECT: Engine Campaign Procedure

MODELS: 535i, 635CSi, 735i, L7 (1985-86 Model Year)

Condition: Idle speed fluctuations. Rough idle. Idle dips below specifications on deceleration.

Cause: Engine systems not updated to latest configuration.

Correction: Perform Engine Campaign Procedure as outlined in this Bulletin.



Campaign
Summary: Because of the interrelations of various components, it is very important to follow the procedure below. Details of these items are included in the next section of this Bulletin.

1. Check Ignition Components.
2. Check/Replace Pneumatic Purge Valve and Vacuum Delay Valve.
3. Check/idle Speed Regulating Valve.
4. Adjust Valve Clearance.
5. Reseal Electrical Connections of O2 Sensor.
6. Clean Fuel Injectors/Check A/C Freon Charge
7. Perform Engine Test with BMW Service Tester.
- Perform Engine Test
- Compare Nominal Value to Microfiche and Adjust if Necessary.
8. Perform Quality Control of Installed Systems and Road Test for Driveability Problems.
9. If Driveability Unsatisfactory, Clean Carbon from Intake Valves.
Campaign
Details: 1. CHECK IGNITION COMPONENTS.
- Remove, inspect and regap spark plugs (See S.I. 12 03 85 (1085)).
- Inspect ignition cables for visual signs of arcing. (See appropriate Repair Manual)
- Inspect Ignition Coil Cap Cover (See S.I. 12 02 85 (1071)).

2. CHECK/REPLACE PNEUMATIC PURGE VALVE AND VACUUM DELAY VALVE. Examine existing pneumatic purge valve. If no date code or if date code is F01 or lower, replace valve. Also install vacuum delay valve. See S.I. 13 05 85 (1048) for details.
3. CHECK/REPLACE IDLE SPEED REGULATING VALVE. Examine existing valve, if date code is before date code 452 replace valve. See S.I. 13 01 85 (972) for details.

4. ADJUST VALVE CLEARANCE. Adjust valve clearance to 0.30 mm cold engine - maximum coolant temperature 95~F/35~C) or 0.35 mm with engine fully warm.

5. RESEAL ELECTRICAL CONNECTIONS OF O2 SENSOR. Refer to S.I. 11 03 86 (1182) for details.

6. CLEAN FUEL INJECTORS. Refer to S.I. 13 08 86 (1176) for detailed procedure. CHECK A/C FREON CHARGE. Refer to S.I. 13 04 85 (1036) for details. Connect the Fuel Injector Cleaner as described in the above bulletin. Once you get to Step 10 of this S.I., do not run the engine at 3000 RPM as described. First run the engine at 2000 RPM and check the Freon of the A/C system as described in S.I. 13 04 85 (1036). Bleed if necessary. After you finish bleeding the A/C system continue the injector cleaning procedure as per Step 10 of S.I. 13 08 86 (1176): Increase the engine speed to 3000 RPM and keep it there until the engine starts to stumble steadily indicating it has used all the cleaning fluid.

7. PERFORM ENGINE TEST WITH BMW SERVICE TESTER.
- Perform Engine Test
- Compare nominal value to Microfiche and adjust if necessary.

8. PERFORM QUALITY CONTROL OF INSTALLED SYSTEMS AND ROAD TEST FOR DRIVEABILITY PROBLEMS.

9. IF DRIVEABILITY IS UNSATISFACTORY, CLEAN CARBON FROM INTAKE VALVES. Follow the Procedure in S.I. 11 10 85 (1011).


GROUP 11 Engine
Bulletin Number 11 10 85 (1011)
SUBJECT: Labor Operations/Allowances for Cleaning Intake Valves/Ports with Carbon Blaster

MODELS: All

Situation: With the availability of the BMW approved Carbon Blaster, cylinder head removal is no longer necessary to clean carbon from the intake valves/ports.

Repair
Procedure: 1. Remove and install intake manifold per applicable Repair Manual.

2. Clean intake valves/ports (using BMW approved Carbon Blaster) per copy of enclosed "Instructions for Operating the J35532 Carbon Blaster".

Warranty
Status: Defect Code: 11 34 00 76 00



The above times are for cleaning the valves. They do not include:

Removing/installing intake manifold (Labor Operation 11 61 050);

Removing/installing valve cover (Labor Operation 11 12 000);

Removing/installing thermostat housing (Labor Operation 11 53 020);

Removing/installing branch flange-4 cyl. only (Labor Operation 11 53 050).
Please refer to the Flat Rate Manual for the applicable labor times.

Reimbursement for carbon removal will be provided through normal warranty processing once only for a given chassis number up to 50,000 miles or 5 years.
Customer Relations

Information: The carbon build-up on the intake manifold side of the intake valves can have two (2) sources. The main source is from the fuel itself. The gasoline oxidizes, leaving a carbon layer on the back side of the valve. The other source is from excessive oil which may leak past the intake valve guide seal and oxidize on the back side of the intake valve. It is very difficult to differentiate between the two sources of the build-up and possibly it is a combination of both sources. The rate of build-up can be minimized by the customer in the following ways: