Engine Performance - Idle Speed Dip
SECTION2
GROUP
28
No.
916
DATE:
March 1995
RE: MFI LH 2.4.4 EPROM exchange for idle speed dip when cooling fan engages
900
M/Y 1992- B230FT
REFERENCE: TP 32043/1, SECTION 2 (23, 28) MULTIPORT FUEL INJECTION (MFI) SYSTEM LH 2.4, 700/900 1989-
MFI LH 2.4.4 EPROM exchange
When the cooling fan engages the voltage supply to the idle air control (IAC) valve momentarily dips.
If this happens in hot climate with the Air Conditioning engaged, the idle speed might dip, which might cause body vibrations.
EPROM Application Chart:
Inspect the LH2.4 control module to verify the correct EPROM required.
Note:
The above EPROMs above have a higher idle speed. This will reduce the condition with the idle speed dip.
With these new EPROMs, the vehicle speed at idle in gears R, D, 2 or 1 will increase from approximately 5 - 7 mph.
(*) = These are not replacement parts.
Replacement of EPROM
EPROM kit contents:
- EPROM
- Sticker "Scrap"
- Sticker "Volvo ID No. -"(9434245-8, 9434246-6 or 9434247-4)
Method:
Turn ignition off
Remove control unit fuse no 1.
Disconnect the connector from the control module.
IMPORTANT:
To avoid damage to the control module, ensure that there is no power to the control module when connecting or disconnecting the connector.
Remove the screws retaining the control module.
Remove the control module from vehicle.
Work area and special tools
Carry out the replacement the EPROM in a permanent working area not directly attached to the workshops. The location must be clean, e.g. free from dust, dirt, oil, solvents, etc. The work must be carried out on a static dissipation mat. The mat must be kept clean and be grounded by connecting it to a grounded system, water pipe or another reliable grounding point.
Special tools
- Static dissipation mat
- EPROM extractor tool
- EPROM insertion tool
Small pliers and screwdrivers
All tools used must be Electrostatic Dissipative (ESD) approved
To prevent condensation inside the control module it must have been at an ambient room temperature of 72°F (22°C), for at least an hour before opening it
Place the static dissipation mat on a clean surface. Connect the ground wire to a suitable ground point
Wash your hands in warm soap and water. Do not apply hand lotion after washing.
Caution:
Attach both the wrist strap and static dissipative mat to the same ground point.
Fit the wrist strap around one wrist (to eliminate static electricity), adjust wrist strap to fit snugly.
Place the control unit upside down on the static dissipation mat. Using a small screwdriver, open the control unit by bending the tabs up. Fully open them with pliers.
All tools must be ESD approved.
Turn the control module over so that the cover is up.
Place the control module so the connector is away from you.
Carefully lift the cover making sure that it does not come in contact with the components on the circuit board.
Remove the EPROM cover
Insert a small screwdriver (ESD approved) in each slot on the cover and pry carefully.
When it is loose, lift it.
Mark the EPROM with the "scrap" sticker provided in the kit; this will prevent it from being reinstalled in error.
Place the extractor over the EPROM to be removed, pressing the grips together until the prom pops up.
Put the EPROM aside.
Note:
DO NOT re-use the replaced EPROM.
Remove the new EPROM from the kit and open the EPROM box.
Caution:
Do not touch the EPROM
Extract the new EPROM using the insertion tool (press in the button on the side of the tool when applying the tool over the EPROM).
Check that none of the pins on the new EPROM are bent.
(If a pin is bent, loosen the EPROM, place it over the gray part of the shaft on the tool, and gently straighten the pins).
Important:
Align the notch in the EPROM with the notch in the socket base.
Carefully locate the EPROM and press it down with the insertion tool. Do not press the button. Remove the tool and check that all pins are correctly located in the socket.
Install the EPROM cover. It must be securely closed.
Install the control unit cover carefully.
Bend the tabs down using ESD approved pliers.
Caution:
To avoid damaging internal components, DO NOT use excessive force on the case when closing it. Do not, under any circumstances, bang or hammer on the control unit. Do not place it in a vise.
Make sure that the cover is secure and all tabs are tight.
Write date and dealer code under the figures on the new "Volvo" ID No. label, and place it on the top of the the existing "Volvo" ID No. label on the control unit.
Leave part of the old label visible (10 digit Bosch number) however; cover the bar code.
Screw the control module into place. Connect the connector to the control module.
Remount fuse no. 1.
Reset any DTC's set. Test drive the car, verify repair.
WARRANTY STATEMENT: Claims may be submiffed under the New Car Limited Warranty when a manufacturing defect is present using claim type: 01
Operation No. Labor description Time allowance
02383-6 E-PROM exchange 0.5 hr