@@@Stepper motor BYPASS or need pressure spring(missing)

[brent88]

Hey, sick of my car fluctuating revs by 500rpm when acc pedal not pushed! took the stepper motor apart and the ''pressure spring''(the one that sits on the bearing is not there) SOOoooo does anyone want to sell me 1 working or not and i can try and make 1 of the 2 or can i bypass it?

http://homepage.ntlworld.com/jaycom/fto ... epper1.htm is a link with a diagram of the inside of the stepper motor


TAKEN OFF THE INTERNET: In the coupe (and I'm pretty sure the fto too), the throttle body has a little water bypass from the main engine cooling system. This means when you start the engine, cooling water (which is warm, then hot) flows through the throttle body. This is meant to stop any potential frost-seizing of your throttle body for the first minute or so of running after a cold start in cold weather.

Of course, it also has the effect of ensuring your throttle body is maintained at the same temperature as your cooling fluid all the rest of the time (80-90*C). As your air flow into the engine passes through it, it'll warm up nicely too (which isn't really what you want - hot air is less dense = poorer combustion, lower power).

I run the risk of a possible stuck shut throttle (in extremely cold weather) to prevent purposefully heating the throttle body. If its that cold i probably wont be driving a sports coupe! Maybe it makes a meaningful difference when running a CAI, maybe not, but personally I think it does make a difference on my coupe compared to before I refiners it. Certainly there's no point in a CAI with it still plumbed in.




Thanks

[Bennoz]

I've got some spares. God knows if they work or not - $40 plus postage

[brent88]

bypass? can i do this? many cars have survived without them? maybe easier to just replace.

looking through forums it looks like cyberspace on ebay have them for around $100 with postage so i will chase this up first but thanks

[Shane001]

On the racecar I've disconnected the water hoses to the throttle body, haven't touched the stepper motor though, so this is still connected. Didn't affect how the car runs, starts or idles.

I expect it will have had a minor affect on air intake temp though from what I've read it will be minimal.

[silverGPX]

Wtf it has water going to it?

[phunkydude]

Didn't know fto got water injection!!!

[Bennoz]

Yes, the TB is water cooled.

[phunkydude]

[silverGPX]

Why is it watercooled?

[brent88]

so the butterfly dosent jam on realy freaking cold mornings i think but the stepper motor controls it and stops the water injection on the proviso it is working......... thats my understanding

[Shane001]

No it's not water injected There is no water actually entering the intake.

All this does is water heat the throttle body to prevent the butterfly siezing at startup in cold weather.

And to be honest from memory I really don't think the stepper motor actually has a lot to do with this. It works regardless of wether the water hoses to the throttle body are connected or not. From what I understand (and I could be completely wrong here as I haven't really looked at this closely) doesn't the stepper motor act like an automatic choke, increasing the idle rpm until the engine is warmed up?

[brent88]

which is why i want to bypass it.... i know cold air compresses better (1-2% power gain) and at night the car seems to be a lot faster....... leads me to believe that because the ''pressure spring'' isnt there its stuck on either as shane says some sort of choke or no choke or maybe because the spring isnt there its free to fluctuate rapidly..... any thoughts on bypassing? maybe a realy strong spring behind the bearing?

been offered a stepper motor for free in melb thats 5got 50/50% chance ofg working but between the 2 i should be right.....failing that i can use a galant gsr stepper motor which i can buy new off ebay for less then $110 and other members have brought them and have worked for years:)

[silverGPX]

Get the spring out of free one....

[brent88]

yeah if his dosent clean up thats what ill be doing:) ill make 1 of the 2 im 70%sure

[payaya]

Why not test the coils to see if they are burnt out??

[silverGPX]

Why is there @ symbols in the thread title?

[Storm]

All the stepper does is adjust the airflow into the throttle body at closed throttle, which is why Mitsubishi call it an Idle Speed Controller or ISC.


You really cant modify it to do much more than this.

[payaya]

Dunno what ya trying to achieve just a stepper doesn't give you extra performance period. Running a damaged stepper can also damage ya ecu.

The fluctuation of idle can also be caused by other factors. Just change ya stepper and be done with it. It's not expensive!!

[brent88]

im pretty sure its the stepper, when u have a loud exhaust like i do its embarrasing, have read heaps of things and i have all the symptoms and i had a wrck fto 6 months ago that i used its stepper motor and it acted up differently.

got 1 lined up anyway:)

[silverGPX]

@@@@ good work! @@@@