so ive noticed when starting my civic the rpms go below zero so i have to heat it up for more than 10 mins up to when the temperature meter is almost at the 3rd bar then when im running it it stays a little over 1 and when i turn my ac on it goes back down but attempts to turn of in the process of slowing down ? ive heard so many things but wanna know what it really is and if there 2 different problems or just one simple one thats causing all this wreckage.

 

Pulled from the rules stickied at the top of this forum.

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clean your IAVC, its on the back of you manifold. If you have unplugged any sensors, chances are you have that mixed up with another one.

 

I'm not sure what that means, but I know that engines can't spin negative revolutions...

 

Sounds odd, but my neighbor had a honda with this issue and just made sure the coolant was topped off to the correct level. RPMs steadied out.

 

Check your coolant level, sounds like you may be low and possibly have a leak. If so find the leak and bleed your coolant according to the FAQ. You may also need to clean your IACV and FITV as in the FAQ as well.

 

Could be the tps as well..check the voltage,if u have poly mounts it could have worked it lose. And also try turning down your idle,that helped mine.

 

Could be a possible vacuum leak. Check all hoses associated with vacuum. Also make sure coolant is topped off. When the car is warmed up unplug the IACV. If there is a change in RPM than most likely the IACV needs replacing or a really good cleaning.