Hard Start Cold Hesitates

PARAUTO

MEMBER
1987 NISSAN STANZA
4 CYL
2WD
AUTOMATIC
200,000 MILES

I am working on a 87 Nissan Stanza 2.0 fuel inj. Auto. It starts hard cold and hesitates untill car runs a minute or two then is OK. If you add fuel it is ok during that time. We did replace the head gasket and T belt. I think it ran Ok before work but did not really try to start cold. Replaced cap, rotor, wires, TPS and temp sender. Does not Speed up idle on cold start up but will when A/C is on. What enriches the engine on cold start? And how do you check. No codes stored.

3 Replies

KHLOW2008

MECHANIC
41,814 POSTS

The IAA and Air regulator valve are part of the idle control system. Get them cleaned and retest.

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Tuesday, February 15th, 2011 AT 8:26 PM

PARAUTO

MEMBER
2 POSTS

Have checked and cleaned and tried one off of another car I am ase master certified and l1 I do know a few things I want to know how the computer enrichens on cold start which sensors and how does it enrichen since it does not have a cold start injector

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Saturday, February 19th, 2011 AT 9:39 PM

KHLOW2008

MECHANIC
41,814 POSTS

The coolant temperature is the main controlling component for cold start enrichment.

COOLANT TEMPERATURE SENSOR
� � � �
This sensor provides ECU with engine temperature information relating to warm-up enrichment operation. Some models use a dual-sensor element which also signals the ignition computer (if equipped).

During warm-up period after a cold engine start, additional fuel is required to maintain engine performance. As engine temperature increases, the ECU decreases fuel enrichment until engine reaches normal operating temperature.

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Sunday, February 20th, 2011 AT 12:15 PM