Coolant Bypass on H22a - Honda Prelude Forum

shiftgearz · 05-15-2003, 09:51 PM

....yes I tried searching, the post that I found with the link was dead....

Pics on Brady's site was for h23a...

Anyways it's dark out and I figured I would ask before I attempt to do it tmr, dont wanna d/c the wrong hoses...

TIA

Zimmlude · 05-15-2003, 10:00 PM

The H22A is the same in that respect as the H23. The only difference between the H22 is in the internals and the head. The IM for the two is almost identical.

shiftgearz · 05-16-2003, 06:11 AM

thanks I'll just try it using brady's as a reference. I was hoping for pics though.

prelude styl · 05-16-2003, 08:35 AM

It's actually NOT good to do this 'coolant bypass' free mod. The coolant running through the TB serves a purpose. That valve that the coolant runs into and out of is waht controls how fast your car idles. When the valve is open(the coolant running through is cold, or not at operating temp) the car idles higher, at 1500rpm, that valve is why the car idles up while it's cold, if you take the coolant away, the car will never reach temp, and will always idle high. When the coolant is at temp the thermo valve closes, and the car idles normal.

G_Loc · 05-16-2003, 09:37 AM

no, its a good idea as long as you block off the ports in the fast idle thermo valve... then your idle will be normal. if you do the bypass without blocking off the ports, then your idle will fluctuate from like 1k to 2k.

i have it done and no problems whatsoever.

prelude styl · 05-16-2003, 10:51 AM

I guess if you block it all off it would be fine.

concLude · 05-16-2003, 07:10 PM

hmm, i guess i'll give this and dohcpower's fast idle block off plate, and see what happens, maybe even the EGR if i'm feeling up to it. haha

prelude styl · 05-16-2003, 07:18 PM

Your JDM H22 came with a fast idle valve?? Mine didn't. It had a little plate there(from the factory) instead of the valve. Weird...

concLude · 05-16-2003, 07:25 PM

<----using h23a manifold and throttle body, i'm almost positive its whats causing my jumpy idle in the cold weather.

prelude styl · 05-16-2003, 08:55 PM

what happened to the intake mani from the H22?

4bidden · 05-16-2003, 09:02 PM

prelude styl, what you said about always idleing high is not true at all.

The engine still senses the car is not at operating temperature somehow besides that valve. I have the bypass done and when I first start the car in the morning it will sit at about 800 for roughly 3 seconds, then go up to normal rpm for warming up, about 1500. Then it idles back down like normal when it reaches operating temp.

prelude styl · 05-16-2003, 09:06 PM

that's really odd, because that valve is the only thing that lets more air into the manifold to raise the idle. If you don't have it connected, then your idle shouldn't go up at all....

4bidden · 05-16-2003, 09:10 PM

Well, its sure as hell not connected and sure enough my idle raises on its own.

I promise.

prelude styl · 05-16-2003, 09:31 PM

I'm not saying you're lieing, I'm just very confused as to how it's doing it.

G_Loc · 05-16-2003, 11:01 PM

my car idles high when cold and i have all that done

prelude styl · 05-17-2003, 09:26 AM

...still confused as to why it's doing it.