Nissan Repair: Cold start 86 nissan, fiberglass column, nissan 4x4

Question
Expert:  Calvin Iwashita
Subject:  cold start 86 nissan
Question:    QUESTION: Hi, I have a 86 nissan 4x4 pickup Z24 motor 5 speed stick shift, when cold it starts no problem but runs rough and i have to give it extra gas until it warms up when hot it starts good and runs great . Thankyou for any Help .

ANSWER: Hi Garry -

This could be several things, so let's start with the most basic -

If you do not have the engine light on, first thing I would look for is a vacuum leak, pertaining to when the engine is in the "cold loop" function. Best way to check this is when the engine is idling rough, spray some carb cleaner sparingly over different parts of the engine. If and when the idling improves, you have found the source of the leak. Repair this and retest the idle. Usually it is a vacuum hose that is cracked or broken off.

Let me know how this goes and get back to me -

Hope this helps -
aloha
calvin

---------- FOLLOW-UP ----------

QUESTION: Thanks for your reply, i did the vacuum hose test but no leaks were found all so the engine light is not on . do you have any other checks i can do ? Once again Thankyou.   
Answer:  Hi Garry -

About 2 minutes while the engine is running rough, can you remove one spark plug and tell me what the color of the electrode is? Should be a light tan color.

During engine warm up, it is running in what you call a "cold loop". Perhaps one of the components that activates during this loop is not operating properly. The spark plug will give a clue.

Aloha
calvin

Hope this helps
Aloha
calvin
Follow up  
Did the plug test they where dry and light tan in color is there something else i should check ? Thanks again Garry .Happy Holidays  


    


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Answer
Hi Garry -

Couple other things you can check is the Mass airflow sensor. This is in the intake boot area. Sometimes it collects debris. Do not use carb cleaner to clean this. They sell special cleaners at the auto parts store.

Also clean the throttle body, inside by the butterfly valve (need to remove the intake boot for this). sometimes debris collect and the valve does not seat. Best thing to use is Sea Foam, also available at the auto parts store.

aloha
calvin