bad idle

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spiritofjosh

spiritofjosh

know your role!
Excuse the language but I think my Eg has a vacuum leak somewhere. Thing is it did it when I first got the car 3 years ago, swapped out the old d-series non vtec with a jdm d15b. It went away for a little and did the same thing again, and now its been doing it constantly and way worse.

When I'm stopped and idle the motor surges or revs up and down like its breathing in and out heavy is the best way to describe it. I did some research and I found something that lead me to believe it might be my throttle body. I think when I put the new motor in I used my old throttle body off the old motor, so if that was the problem it wouldn't of went away.

My real question is how do I locate a vacuum leak if that's the problem? Or if its not the tb then what else could it be?
 
It could be a vauum leak or your IAC. Since you used your thottle boddy from your previouse build, that could be the issue. Make sure the air passages are clear.
 
The next day its nice I'm gonna take a look at fitv bc i never thought of that, i guess one thing at a time. But say its none of that what about the vacuum lines themselves?
 
also a cracked intake manifold can cause this, or a small leak in your intake manifold gasket... I just turn on my defrost or lights and put a small load on the motor and mine goes away lmao
 
hondafreak513 said:
Next I would make sure you have enough coolant in it and no air in the system..
Click to expand...

The first thing I did was flush out my rad and refilled it with fluid because it was really low on coolant, then bingo, it stopped idling like that, good looks.

Which brings me to wonder what exactly is up with my rad in the first place, its a mishimoto with stock fan (unfortunately) and it burns through rad fluid often. It seems every 2 or 3 days I have to top it off with fluid, is it because it's an aftermarket rad? I feel like an idiot for asking that by the way.
 
Also, what kind of cap are you using. If your using your stock cap, it may be too weak for your current setup. You'll want a 1.1 bar (16psi) cap. Also, like hondafreak513 said, check your lines, including your heatercore lines and tstat gasket for any bypass. All it takes is a small amount of corrosion on any of the metal to let fluid by the hose during operation.
 
you cold also check the water pump and see if its going through the weeping holes. happened to me and couldnt figure it out for awhile lol
 
The water pump will be next once it's nicer out, but I checked all the lines etc when I flushed the rad out and they all seemed ok. And yeah I'm using the stock rad cap.
 
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