Engine and Transmission Tech

Curtis,

Normally its best to adjust the butterfly stop so that it will allow some air to pass for your true minimum idle setting. (usually 500-600 RPM)
Also it prevents the throttle from sticking or binding closed as the venturi and butterfly plate goes through temprature changes or throttle coking.

Bill

Be careful, you may fool the computer in thinking your giving it throttle by moving the TPS voltage up when turning the throttle stop. I'm not familiar with the Rover system but most of other EFI brands you have to use a filler gauge when adjusting that screw and also check the TPS voltage output with the throttle at rest. The computer should know what RPM the program calls for at idle and maintain it through the air idle control motor.........

On my Ls1 throttle body, probably not related to speed density, or what Curtis is using, but it might. I opened up my blade enough to get the right TPS voltage in my HP tuners software. When you mod your engine like I did, the engine needs more air to idle right without hunting for idle. The air idle control will go open and close trying to get the engine to idle right. Some people will drill a larger hole in the throttle blade which I didn't want to do. So when the blade is open farther to let in more air, once you have the voltage where you want it, then unplug the TPS after turning your key off. Then turn your key back on with it unplugged for a few seconds (This will reset your TPS to home position), turn off your key, plug TPS back in and when you turn your key back on, it will read that the TPS is not open any percentage. If you go to far the engine will hunt for idle again.

Hope this helps!

On the Megasquirt you set the TPS lower voltage for the closed position, it is an easy step in the setup process. Your laptop shows you the voltage and you burn that as the reference. You can put it anywhere you want so the throttle blades can be open any amount. So Curtis' question is very relevant. Some guys like to set the throttle blades so the engine will run without the IAC and then use that to compensate for added loads. I think setting it for the minimum possible engine speed and then using the IAC to hold the preferred idle RPM makes better sense. The range of airflows needed needs to be within the range of what the IAC can deliver. As for the rubber tip, it's a fair point but probably a lesser concern.

Another thing is that MS3 can do throttle blip on downshift. Not a whole lot of need for it in a manual transmission car but something that could be useful some day. A high flow IAC might be helpful in that regard.

Jim

So much to learn . . .
Curtis, how's that crank-fired ignition system coming along?

Tim

This is driving season! I'm planning/hoping to get on track with NASA this coming weekend. (That's not too terribly expensive - but it does cost more than a set of used LS coils, so I have mixed feelings about the commitment.) Cam position sensor looks like it'll come together easily and cheaply. Those components have been purchased. I need to source some wiring stuff too. (Ford connector and terminals for the cam sensor? Delphi/Packard stuff at the coils?) And spark plug wires! (I've got no idea where to get the best deal on a custom tailored set or on suitable components and tool. Suggestions?) I don't expect to bolt any ignition parts on until after the first snow.

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Calibrating the TPS couldn't be easier, by the way. In TunerStudio, you mouse-click on one button to set the closed position. Depress the throttle pedal and mouse-click on another button to set the open position. Dead simple and quick.

Do the NASA track deal! Guaranteed to be waaay more fun than a used set of coils! Besides it will be good for you.

Curtis, Junkyard for the wire connectors. Look in Summit,Jeg's and Speedway Motors for a roll of sparkplug wire and terminals,crimping tools,etc. Accel,Taylor and MSD have universal sets where you cut to length and just do one end. Probably 8mm wire. For radio suppression the coiled solid wire is much more durable than carbon core.