Rough Idle During Warm Start

[Dylan Shrout]

I have had a long term issue with my 1995 Integra. It starts and idles great during a cold start, but whenever I start it when the engine is warm it idles very low and sometimes cranks but doesn’t start. I have noticed weird symptoms with the cooling system. Heat only goes in the cabin when I’m accelorating and it almost seems I am constantly having to add coolant (not %100 certain if it is losing coolant). No signs of a blown head gasket. Engine doesn’t overheat nor is there smoke coming out of the tail pipe. Other than that, it runs pretty good. Feedback is appreciated 🙂

Topic

[Mike]

There is a thermostatic idle control valve where small coolant hoses go into the throttle body. If coolant doesn’t go thru it to warm it up as engine temp rises up to normal, the idle behavior will be terrrible when warm. A lot of times, neglected coolant will gunk up and clog that area since it’s the smallest pipes in the system. It will prevent hot coolant from flowing thru and warming it up like it’s supposed to. The same thing will happen if the coolant is too low and there is air in that area. Your needing to have the engine rev to produce heat is also a symptom of low coolant level. It sounds like you need to find and fix your leak, flush your cooling system manually with a hose, and get it properly filled and burped.

[David Arias]

My 91 toyota pickup 4×4 is experiencing something incredibly similar to what you describe here, im gonna go ahead and look for that potential coolant leak, so thank you very much for that.
However, I’m also noticing that my engine oil level is dropping pretty quickly and a black residue tends to be found on the floor near my tailpipe (seems to be happening when I start it, but could very well be spilling all over town, not too sure). Would this be related to the warm rough idle issue, or would that be a separate problem all together? I would really appreciate any insight that you might be able to provide!

Thank you.
-David

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