Using cold start solenoid as a throttle?

[Nev62]

The mighty Raider does not have a throttle which means the odd stall when crawling. What I was thinking of doing is either hooking up the cold start solenoid to a switch (on = 1200 RPM, off = 750 RPM). Is this okie dokie or would it just stuff the solenoid

[dumbdunce]

The mighty Raider does not have a throttle

eh?? you mean it doesn't have a hand throttle?

which means the odd stall when crawling. What I was thinking of doing is either hooking up the cold start solenoid to a switch (on = 1200 RPM, off = 750 RPM). Is this okie dokie or would it just stuff the solenoid

does the cold start valve open or close with power applied? some have +12v applied all the time to close the valve in which case you might be able to wire a switch in series with it to turn it off to up the idle, however the response of these valves is pretty slow. also it may or may not upset the ECU.

does it have air conditioning? does it idle up when the air cond. is on? could try wiring a switch to block the signal to the compressor clutch, so you flick the air cond ON and the switch OFF so the ECU thinks the air cond. is on, and idles it up, without the drain of running the compressor.
If the air cond. idle up uses a throttle positioning motor/actuator then you might be able to wire directly to the actuator depending on its type and mode of operation.

or just get a diesel and you won't have to worry about it.

cheers

Brian

[murcod]

Safer option could be to buy another solenoid and plumb it in to bypass the throttle body and wire it totally separately to the ECU. Could save a very expensive mistake!

[dumbdunce]

Safer option could be to buy another solenoid and plumb it in to bypass the throttle body and wire it totally separately to the ECU. Could save a very expensive mistake!

this could potentially still fool the ECU. if the engine uses a MAF then it will be necessary to draw the extra air through the MAF to keep the mixture right, and even then the ECU might get confused about an airflow that doesn't match with the throttle position switch still being in the idle position.

might need a little fooling around to lift the throttle position sensor to 'cruise' or even 'power' position (most throttle position sensors are 3-position switches with idle, cruiser and power positions, but some are a pot which would be harder to fool).

if the EFI uses a MAP instead of MAF then you can pull the air into the manifold from anywhere, as long as it's filtered.

another solution: you could buy a cheap cruise control and use the distributor/tach signal (stick a 1 W 4k7ohm resistor in series to reduce the amplitude) in place of the vehicle speed sensor signal, then you can program it for a constant RPM rather than a constant road speed. This could actually be really good for crawling, especially if you can program the gain* on the cruise control - with high gain it's possible the cruise could compensate quickly in terrain and attempt to maintain a constant rpm while you climb.

Food for thought anyway. if you're interested in experimenting with this kind of stuff I am keen to hear how you go. I could have my arm twisted into contributing a little bit of time in development if you want.

*gain is a measure of how rapidly and how much the throttle is adjusted in response to to speed/rpm changes


cheers

brian

[Nev62]

I had not thougt of the ECU. I like the idea of the curise control module to control the RPM so will give this a go. Thanks for the input guys.

Brian, I just may do a little of that arm twisting when I get start in a couple of weeks (would like to start now but got a full plate for the next couple of weeks).

[dumbdunce]

I had not thougt of the ECU. I like the idea of the curise control module to control the RPM so will give this a go.

now you just have to find a cruiser control that will accept a tach signal instead of a VSS signal. I know several of the Autron 'Auscruise' models will work this way but they won't sell direct to the public... I'm sure there are other models out there that could be made to work this way though. who knows even a $200 k mart job might work.

let me know when you're good to go, I have a fair bit on the next few weeks too but not sure what I've got on after that.

[Nev62]

I had not thougt of the ECU. I like the idea of the curise control module to control the RPM so will give this a go.

now you just have to find a cruiser control that will accept a tach signal instead of a VSS signal. I know several of the Autron 'Auscruise' models will work this way but they won't sell direct to the public... I'm sure there are other models out there that could be made to work this way though. who knows even a $200 k mart job might work.

let me know when you're good to go, I have a fair bit on the next few weeks too but not sure what I've got on after that.

This might be something to do over the chrissy break.

[dumbdunce]

I had not thougt of the ECU. I like the idea of the curise control module to control the RPM so will give this a go.

now you just have to find a cruiser control that will accept a tach signal instead of a VSS signal. I know several of the Autron 'Auscruise' models will work this way but they won't sell direct to the public... I'm sure there are other models out there that could be made to work this way though. who knows even a $200 k mart job might work.

let me know when you're good to go, I have a fair bit on the next few weeks too but not sure what I've got on after that.

This might be something to do over the chrissy break.

yeah could be the go. just remembered I'm going to Perth for 10 days in November ,will be 18th November before I'm home so after that it could be worth looking at.

cheers

[Nev62]

going to Perth for 10 days in November ,will be 18th November before I'm home so after that it could be worth looking at.

Not a problem. Was thinking of sometime in December. I'm going to see what is about and price (will probably go cheap and nasty just in case it turns to custard).

[dumbdunce]

going to Perth for 10 days in November ,will be 18th November before I'm home so after that it could be worth looking at.

Not a problem. Was thinking of sometime in December. I'm going to see what is about and price (will probably go cheap and nasty just in case it turns to custard).

mmm.. custard... goes well with Christmas pudding.