Nissan Repair: cold start 86 nissan, nissan 4x4, vacuum leak

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