cold start valve
02-18-2003, 12:50 PM
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I don't know what "mod" you are talking about. I know I'll lose a little bit of unnecessary weight when I remove my AIV. But the HP gain was from negating it with straight pipes. 
02-18-2003, 01:03 PM
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Just about every stock car has a feature called the cold start valve. The cold start valve is located on the bottom of the throttle body and it has two lines that run into it, one in and one out. The lines transfer coolant which in a cold start situation, helps warm up the engine faster by warming up the air in the throttle body via-coolant. In a cold climate(one that has regular temps below freezing) it has a purpose, but in summer months or a climate that doesn't have a winter of freezing temps, the cold start valve hurts hp because hot air is bad air.
02-18-2003, 01:06 PM
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Bypass the valve by running line #1 where line #2 connects back into the block. Now you have coolant going out of the block and back into the block, which is essentially what it did before, but it doesn't go through the throttle body which drastically reduces air temps in the intake manifold.
02-18-2003, 01:17 PM
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I dont know if what im about to say applies to all cars, but it does to my car. Those coolant lines dont just flow when its cold, it does so all the time. It does this to burn off the crud that accumulates from the EGR valve. Unless you disable that, you will have alot of crap build up in there. The cold start valve that I thought you where talking about is on the bottom of the intake manifold and it allows extra air in until the engine warms up to raise the idle so the engine warms up faster.
02-18-2003, 02:12 PM
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The AIV warms up the cat? The AIV, afaik, does not warm up the cat. It introduces air into the exhaust stream to help the cat convert co to co2. It does so (at least on my car), when the throttle snaps shut b/c when this happens, the car runs rich b/c of port wall wetting. This was later fixed on the low port models of my engine by places teh injectors closer to the intake valves and increases intake air velocity.
02-18-2003, 02:31 PM
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Originally posted by non-vtecpower
Just about every stock car has a feature called the cold start valve. The cold start valve is located on the bottom of the throttle body and it has two lines that run into it, one in and one out. The lines transfer coolant which in a cold start situation, helps warm up the engine faster by warming up the air in the throttle body via-coolant. In a cold climate(one that has regular temps below freezing) it has a purpose, but in summer months or a climate that doesn't have a winter of freezing temps, the cold start valve hurts hp because hot air is bad air.
Just about every stock car has a feature called the cold start valve. The cold start valve is located on the bottom of the throttle body and it has two lines that run into it, one in and one out. The lines transfer coolant which in a cold start situation, helps warm up the engine faster by warming up the air in the throttle body via-coolant. In a cold climate(one that has regular temps below freezing) it has a purpose, but in summer months or a climate that doesn't have a winter of freezing temps, the cold start valve hurts hp because hot air is bad air.
da -yummm