Civic EG

so my del sol has been acting up lately, and when you turn on the heat it would blow hot then all of a sudden it would shift to cold. and the temp. gage would shoot up when it is cold. any reason why would happen?

never heard of that... did you try changing the thermostat?

well how it all started was the car was idling sort of funny so i got advice on the forum to take the parts by the tb. which i did so. but it didnt fix the idling. after that i realized that the car started getting hot. and i added water to the resourvior tank. and it still did the same thing. -.-

I recommend hooking those coolant lines back up to your throttle body, especially when trying to diagnose a problem.
Honda made it that way for a reason
Your those coolant lines help our ecu determine if your engine is up to operating temp.
If your engine never reached operating temp, your car will run more rich and get worse gas mileage.

Some things to check:
as mentioned replace thermostat - it's cheap.

look for signs of blown or leaking head gasket: white smoke in exhause, sweet antifreeze smell in exhaust, overflowing reservoir tank, oily film on surface of coolant.

air pocket in coolant - bleed coolant system

Perhaps you have an air pocket and that goes into your heater core which gets stuck and that's why your heat then no longer feels hot. Then your engine starts to get hot because the coolant isn't circulating properly.

Next is to find out how air is getting into the system which I have seen caused by a leaking head gasket allowing the combustion chamber to force air into the coolant passages around the cyl.

The ECU has no idea whether your coolant is bypassed from your TB and IACV. There are no coolant sensors near there.

Honda ran the coolant this way to increase idle speed and defrost stuck throttle body plates and IACV internals in subzero temperatures. This is not a problem for most of us.

My guess is that you connected the lines improperly when you did the bypass. Put it back the way it was and see if that fixes it.

To bypass the coolant, you have to run a new hose from (the head output to the FITV) to (the head input of the IACV). You then need to plug the FITV and burp the coolant. And finally you may need to adjust your idle speed.

teal_dx- can you clarifiy what you mean by plugging coolant lines back to the tb? if you mean all the rubbery hoses then i have already did so.


suspendedhatch- i rechecked everything and it looks to be in order. if i ran a new hose i would have to buy and new one or do i use a previous one?

sorry about the noob questions, still trying to learn.

It happened to mines when my FITV was clogged with crap. Clean it out and the cold became cold, and hot became hot. But that is only my experience.

You will need a new one because none of the OEM hoses are long enough.

How could everything be in order if you're missing this hose? Maybe I didn't understand you correctly... did you bypass the coolant to the TB and IACV?

ohhh i think your understanding me wrong. i didn't change anything. i just took the fitv, and ivac and cleaned them. and put everything back into place cause they said that would fix my idle. which it didnt. might be FAIL on my end lol. but everything is put back to how it was oem wise.

so i took my car out to see if it was going to overheat cause when i would run it idel it would be fine. and sure enough it over heated.. in the beginning of driving it was fine. the idle was good, as i kept driving the temp gage just kept rising and the idle suddenly became pulsey. when i got home i heard a sqeaking noise and popped up my hood. to find that the water resivour take is steaming from the top. i shut the motor off. does anyknow the fix to this? i recored a few videos to show you guys excatly what im talking when i say the idle is pulsey and how its overheating. sorry about bad quality pictures it was from my crappy phone. hope you guys can help. thanks in advance.