Elevated Idle Speed - Cold Start and Warm up
303-12V8 Sedan & XK8
DATE: 11/97
SERVICE TECHNICAL BULLETIN
Elevated Idle Speed - Cold Start & Warm up - Base Idle Specifications
MODEL
1997 MY-ON XK8 Range
1998 MY-ON V8 Sedan
VIN
001001-ON
812256-ON
Issue:
Customer complaint of high idling speed during engine warm up period.
BACKGROUND:
Jaguar AJ-V8 engines idle at higher speeds during the warm up period than earlier AJ16 and V12 engines. This may cause unjustified concerns from customers having experience with earlier Jaguar models.
Compliance with increasingly stringent emissions legislation requires an engine management strategy employing leaner air/fuel ratios than previously, requiring higher idling speeds. This may be particularly noticeable to the customer on a cold or partly warmed up engine. Once the coolant temperature approaches operating temperature, normal idle speed will resume.
Action:
In case of a customer concern of alleged high idling speed, particularly on a cold or partly warmed up engine, refer to the idle speeds in the chart. If the observed idle speeds are approximately the same as listed, no defect exists. Advise the customer of the warm up strategy.
A noticeable, but temporary, increase in idling speed must be expected when an engine is started cold, or restarted with the coolant temperature in the zone around 25° C.
It should also be noted that the instrument panel tachometer will indicate an engine speed 50 - 100 rpm greater than true engine speed, as measured electronically by workshop service equipment.
Diagnosis is not necessary unless idling speeds vary significantly from those listed in the chart.
BASE IDLE RPM IN PARK OR NEUTRAL