icarus402001

I have the caddy TBI hat and TPI duct on my 92 RS. Of course, I've removed the heat riser from the exhaust manifold. My warm up time has been longer since I did this 2 or 3 years ago. I'm assuming the IAT sensor has a function in the high idle time, since the coolant temp does not rise as fast as the idle DID drop prior to the CAI install. I doesn't seem to me that any other sensors would apply to warm up. In order to slow the RPM's down sooner during warm up, I'm thinking of installing a manually, or temperature sensitive " valve" in the riser that would allow warmed air into the intake air and then dump the warmed air back into the engine compartment when in closed loop, just as it does now anyway. Hopefully this will stretch my gas dollar( I have a new job and I have to commute for the first time in 23years). I know the savings will be MINIMAL but hey, 100 pennies = $1.00. Am i nuts on my theory? Also, Please no debate over CAI, Thanks.

icarus402001

Anyone have any ideas?

icarus402001

Anybody? Faste355? Dimented? Someone KNOWS the sequence of operation.

BMmonteSS

The IAC has nohting to do with how long the high idle is engaged. This is completley dependent on engine temp and time. If your idle is coming down sooner it's because the engine is warming up faster. It may just be that your factory guage is a little lazy in the mornings.

Also the minimal gain in warm up time you'll get from a warm air system makes it not worth it. The best thing you can do is to use every drop of gas that you put through the engine, mainly just jumping in and hitting the road. After that it's just a matter of making the engine efficent. Headers, intakes, and most importantly tuning will all return measureable results in fuel mileage.

If you haven't looked into it getting into chip tuning would be a worth while investment. These ecm's have whats called a "highway" mode that leans out the mix to between 16 and 17.5 to one AFR under light throttle cruise conditions. Optimizing this and your EGR system can let you run down the highway using very little fuel. On flat ground with tuning guys have cracked 30 mpg with near stock LO3's.

In reality 75% of your MPG gains are going to be your driving style. You also have to think if your mods will ever pay for themselfs. If your hot air system saved you .10 cents a tank and cost $50 it parts and labor, it would take 500 tanks of gas to pay you back.......that's a lot of tanks. I've seen guys ditch their 20 mpg SUV for a 30 mpg car and lose 5 grand on the deal, that price difference would have put gas in their SUV for 50,000 miles.

icarus402001

Thanks for the reply. I'm working on getting a laptop and and cable together to begin datalogging as we speak. I try ti not let it warm up too long before I pull out already. My high idle kicked down after only 30 ir 45 seconds with the stock air cleaner. afteer I went to open element, the idle changed.

BMmonteSS

As long as you aren't beating on the car there is no reason to wait to drive it. I start the car give a second or two to level out the idle and take off. You'll put heat into the car much faster moving under light load.

In reality there is no reason to have a high idle other than to keep the motor running. So the fact that it idles down faster really doesn't matter, although it would be interesting to see why it does. Once you get the logging cable you can get the tuning software out and start browsing through the tables to see what effects your cold startup. (You can do this without the burner) What's cool is when you start watching the camanded idle in WINALDL and then correlate that to the table in the chip. Then it all starts making sense and you can see what and where to make changes.

Once more thing that came to mind, the exhaust crosover in the intake is a much better source of heat to keep the fuel atomized (which is really our goal). The early carb'd cars used a valve in the exhaust to force all the exhaust gasses from one side of the engine through this passage to heat the manifold quickly. I don't condone putting a big ole restriction in the exhaust but you might experiment with this system to see if there are any gains to be had. Some intake gaskets had a restrictor plate on this passage, might want to see about removing it. You just have to be carefull that you don't sacrifice too much "warmed up" mileage for cold mileage.

icarus402001

Thanks for the input. I'm mostly just curious about the high idle time, although it is aggravating. Now that I have a new battery in the laptop, I can try my first cable again. The laptop shut down before, even with the "powered" cable I built. I'll get it right eventually. Thanks again.