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GOOD! START THE
ENGINE THE NEXT
MORNING TO
RECHECK
SETTINGS**
DOES THE ENGINE
STALL IN THE FIRST 2
SECONDS?
YES
INCREASE
AFTERSTART
ENRICHMENT 5% AT
THAT ENGINE TEMP*
ADD 5% MORE
COOLANT TEMP
ENRICHMENT AT
THAT ENGINE TEMP*
DOES THE ENGINE
STALL DURING
WARMUP?
NO
NO
* The actual amount of fuel that
needs to be added depends upon
how far the settings are off.
**The settings may need fine
tuning as varying cold start
conditions change (summer to
winter, etc.)
START THE ENGINE
YES
DOES THE ENGINE
RUN ROUGHLY DURING
WARMUP?
NO
ADD 2% MORE
COOLANT TEMP
ENRICHMENT AT
THAT ENGINE TEMP*
YES
DOES THE ENGINE
CONTINUE TO RUN
ROUGHLY?
NO
YES
Note: This flowchart is slightly simplified. See
accompanying text for details.
Figure 32 EFI Tuning Guide—Cold Start—After Base Map is Tuned Hot
Afterstart Enrichment - Afterstart enrichment is fuel added immediately after the vehicle starts. It is then taken out very
quickly. How much and how quickly is adjustable with tables in the software. Even after the coolant temperature
enrichment is properly set, afterstart enrichment provides and engine with more fuel for a short time that is necessary for
best operation. Like coolant temperature enrichment, how much afterstart enrichment needed has a lot to do with the
camshaft in the engine. Efficient, high vacuum engines with small cams need less afterstart enrichment than engines with
large cams and low vacuum at idle.
Figure 33 Startup Enrichment