Engine Controls - Sensitive Throttle On M70 Engines

91bmw10

Group 12
Engine-Electric


Bulletin Number
12 03 91 (3326)


Woodcliff Lake, NJ
September 1991
Product Engineering


SUBJECT: Sensitive Throttle on M70 Engines

MODELS: 1991 750iL, 850i, and 850iA


Situation: Customers may complain of an overly sensitive throttle on the above models. Minor pedal movements seem to cause abrupt changes in throttle opening.

Solution: An EML control unit EPROM is available with improved dampening characteristics of minor pedal movements.

This EML control unit EPROM will in NO WAY change shift points or the downshift characteristics of the 191 shift maps.

It does eliminate the sudden jerk or load reversal caused by a slight lifting off and reapplication of the throttle.

The attached instructions detail the procedure for EPROM replacement.

EML control units having BMW Hardware Numbers 1 733 599, 1 729 744, or 1 725 400 and Software Numbers F32, D32, or S32 DO NOT require this modification.

Parts
Information: Part Number Application

88 88 6 900 352 '91 750iL
88 88 6 900 352 '91 850iA
88 88 6 900 353 '91 850i

A label with the phrase "BMW NA QUALITY CONTROL" will be automatically included with each EPROM ordered. For purposes of identifying control units, this label must be applied to the front of the control unit.

BMW NA
Quality Control

Example

Spare parts are NOT UPDATED. In the rare event that it is necessary to replace a control unit which has previously received this modification, it will be necessary to update the replacement part before installation to prevent a reoccurrence of the customer's complaint.


Warranty
Information: Covered under the terms of the BMW New Car Limited Warranty.

Defect code: 12 71 00 42 00

Description Labor Operation Model FRU

R & R Control Unit 12 71 530 750/850 3

Exchange EPROM 12 70 000 750/850 2


EML CONTROL UNIT

EPROM Exchange Instructions

Preparatory
Instructions: The installation of the updated EPROM into the EML Control Unit is a simple procedure.

However, before beginning the EPROM exchange, the following conditions must be provided and the designated tools must be used.

ENVIRONMENT

The work area where the EPROM is exchanged must be free of excessive dust and aggressive chemicals or vapors. A small uncarpeted office within the dealership is recommended. Since low atmospheric humidity promotes static electricity, an evaporating bowl of water can be used to raise the humidity of the work area.

EQUIPMENT

Screwdrivers (blade type) are only used to open and close the EML Control Unit. The EPROM is exchanged using an IC extractor/inserter set. Tool sets can be obtained locally (Radio Shack, Archer # 276-1581).

STATIC ELECTRICITY

The EML Control Unit can be damaged and rendered unusable by static electrical discharge. For this reason the 3M static protection kit (or equivalent) must be used during the entire EPROM exchange procedure. See S.I. 04 30 87 (1546) for complete details.

EPROM STORAGE

Replacement EPROMs must be stored in the original shipment containers. The label in the center of the EPROM must never be removed.


Procedure:

CAUTION - Whenever connecting or disconnecting the EML control unit the IGNITION MUST BE SWITCHED OFF.





- Lay the control unit face down on the static mat and remove retaining pin from middle plastic rivet using needle nose pliers.





- Carefully bend up the tabs on the cover only as far as necessary to remove the cover.








- While gently raising back of upper circuit board, release the two front retaining clips in the connector plug.





- Slide the circuit board backwards out of the connector and rotate upwards. Lay open the control unit on the static mat.





- With the upper circuit board removed, remove the EPROM security cap by inserting a small straight blade screwdriver into the slot on each long side and releasing the catch by gently prying outward against the side.





- Remove EPROM from circuit board using the IC extractor tool.





- Install the new updated EPROM using the IC inserter tool.





- The EPROM is correctly installed when the notch in the EPROM aligns with the notch in the IC socket


Assure that all the EPROM contact pins are fully inserted by pushing down on the EPROM until the stop is felt.

- Re-install EPROM security cap.
- Re-install upper circuit board.
- Replace cover and bend tabs down.
- Affix "BMW NA Quality Control" label onto front of control unit cover for future identification of modification to control unit. Label will be included with order.