Engine - Vibration at Idle Speed

84renault2 8E174
FEBRUARY 1984
ALLIANCE/ENCORE
ENGINES Attention: Workshop, Parts Department

VIBRATION AT IDLE SPEED

Information

On some models with automatic transaxle, normal engine firing pulses may generate a slight vibration at hot idle speed when the transmission is in gear.

The vibration is eliminated by installing a jumper harness in the ECU circuit to increase hot idle rpm. The harness steps up the idle mode signal to the ECU and is installed as follows.

Procedure

1. Connect a tachometer to the engine and note hot idle speed with the transaxle in Drive.

a. If hot idle speed is a minimum of 800 rpm, proceed to step 2.

b. If hot idle speed is below 800 rpm, determine the cause using tester MS 1700 and correct as necessary before proceeding to step 2.

2. Pull back the carpet on the right side of the center console below the ECU location.

3. Disconnect the six wire ECU connector from the instrument panel harness connector and install jumper harness, 8983 501 191, between these two connectors.

4. Reinstall the carpeting.

5. Recheck the hot idle speed in gear. Engine speed should be 850 to 900 rpm.

6. Remove the tachometer.

EFFECT OF ECU HARNESS ON BENDIX DIAGNOSTIC TESTER

The ECU jumper harness has the same effect on both A/C and non A/C models. It increases idle speed in either case by sending a step-up signal to the ECU that simulates full-time A/C operation.

On models with or without A/C, before checking the system with Electronic Diagnostic Tester, Tool MS 1700, always remove the jumper harness to avoid invalid tests.
PARTS

Description Quantity Part Number

HARNESS, ECU Jumper 1 8983 501 191

S.R.T. INFORMATION

Operation
Operation Description T.I.C. Number S.R.T.

CO. ECU JUMPER HARNESS - 8-999 8999 0.3
INSTALL

Filing Instructions

Record this I.S. Note on page B-115 and file it in your M.R. 245 binder.