Engine - Ignition Timing, CO and Idle Speed Setting

91vw01

Subject: Basic Engine Settings

Model(s): Golf, Jetta and Cabriolet m.y. 1991 w/Digifant I


Group: 24

Number: 91-03

Date: 1-10-91


Note

The following interim information is being provided to cover the basic engine settings until detailed procedures are released (early March).

Ignition timing, CO content and idle speed, checking/adjusting

^ read fault memory to check for the possibility of stored faults

^ repair as necessary to eliminate any faults and then erase fault memory

CAUTION

Stored faults must be corrected and then erased from memory at this point or the following checks and adjustments could be affected.

Requirements

^ Engine oil temperature 80~ C (176~ F) minimum

^ All electrical consumers switched off

^ Do not take measurements while radiator cooling fan is running

^ A/C switched off

^ Idle stabilizer valve OK (with ignition switched on, the idle stabilizer valve must vibrate and hum)

^ Exhaust system must be leak tight

^ connect SUN 105 (or EPA approved equivalent) CO tester to the CO tap tube using VAG 1363/3 adaptor

^ CO tester adaptor must be securely attached to tap tube to prevent measuring errors due to dilution or leakage





^ connect VAG 1367 engine tester using inductive pickup VAG 1367/8

^ start engine and let idle





^ disconnect* blue coolant temperature sensor harness connector

^ raise engine speed between 2000 and 2500 rpm

^ observe ignition timing (displayed directly on VAG 1367)

^ checking value: 4 to 8~ Before TDC

If NO adjust as follows

^ loosen distributor base clamp

^ adjust ignition timing by rotating distributor

^ adjusting value: 6 +/- 1~ Before TDC

^ re-tighten distributor-base clamp and re-check timing, correct if necessary

^ 25 Nm (18 ft.lb.)

^ reconnect blue coolant temperature sensor harness connector

^ proceed to idle speed and CO checking/adjusting


Idle speed and CO content, checking/adjusting

^ observe idle speed and CO content on test instruments

^ Idle speed: 750 - 850 rpm

CO content: 0.3 - 1.2 vol.%

If NO, adjust as follows

^ switch OFF ignition

CAUTION Do NOT turn or try to adjust the (sealed) screws on the air flow sensor and throttle body.


* Disconnecting the coolant temperature sensor generates fault code 2312 which must be erased after checking/adjusting is completed.





^ remove crankcase breather hose from emission control valve (arrow) and plug off

^ start engine and let idle

^ disconnect blue coolant temperature sensor harness connector (arrow 2)

^ reconnect after 1 minute

^ radiator fan must not be running while re-connecting

^ reconnect crankcase breather hose

^ read Fault memory then erase*, see Repair Group D2, if necessary, for additional information on this topic


* Disconnecting the coolant temperature sensor generates fault code 2312 which must be erased after checking/adjusting is completed.