old idle valves. .. sardonicus. chimongas?

[spitfire4v8]

Asking in here rather than engines section as that doesn't get much traffic in there and you guys are of a certain age (like me) that you'll know what I'm on about ! (no offence intended!!)

I need an old fashioned idle control valve like used on the k jetronic cars of the 80s.

I've got a car in (it's a griff) and I'm struggling with high idle speed coming to junctions. The part of the code in the ecu that deals with this hasn't been found by the clever guys cracking the lucas so some mechanical means of lowering the aiflow is required in the meantime.

I have tried spacers in the stepper motor rod, also tried a restrictor in the air pipe to the stepper. Both techniques I have used in the past to good effect but for some reason don't seem to work well on this car.

Basically I want the stepper to work properly from cold start, but have its effect reduced as the engine warms up

so ..

I want to fit a second control valve inline with the tvr stepper and was thinking the old style bosch units that close down gradually (bi-metallis strip types?) with electrical input are the way to go. I can set the minimum airflow by drilling the central closure disc or effecting a bypass arrangement, but have the full airflow for cold start when the valve will be fully open.

The previous two techniques / bodges either lead to stalling when cold or stalling when hot, or no change to the high idle if the stalling is addressed. Hope that makes sense.

So .. what i need from you guys is the sorts of cars that used a gradually closing idle valve (ie over several minutes).

I used to have a capri 2.8 and sierra xr4iand they had these valves but they also had thermotime switches and used to use coolant as the long term heating element after switching the electrical input off by the thermotime switch.

I would like to find an electrical only version of that kind of idle valve so I don't have to also start rerouting coolant into the valve mechanism.

Does anyone have any ideas ?

any help appreciated, cheers!!

[spitfire4v8]

Bump for the friday crowd?

[ukdj]

Peugot 205 GTI / 405Mi16 / Citroen BX GTI had bosch IAV with usual two/three pin timer plug

Regards

UKDJ

[blitzracing]

You are trying to fix the symptoms, not the illness. If the stepper is holding high as you come to a junction, there is a reason. Most likely cause is a wrong throttle pot input, or speed signal (if its a ford box). Otherwise you may have a plenum air leak. As a really crude fix you can put a plumbers gate valve in the air feed to the stepper and tweek it to keep the idle low by restricting the air.

[spitfire4v8]

You're right Mark i am fixing the symptoms but everything checks out. no leaks, road speed reads zero at rest, 37mph when moving.
What i'm fighting against is the stepper movement when lifting off the throttle .. the ecu automatically moves the stepper back and this is enough to add 1000rpm to the engine speed with no throttle applied. Only after coming to rest does the idle start to return to 1000rpm again.
I can't find any fault as such, it's just a symptom on this particular car that the stepper motion adds 1000rpm rather than 200-300 as per normal.
ive tried spacing the stepper rod (as youve done on your car) and restricting the stepper air pipe, but neither route works well for both hot and cold starts.
So i want to revert to an old fashioned idle control that blends the extra airflow out from cold start over several minutes.
ive ordered a bosch idle control valve and will see how it works.
Thanks for the replies.

[EGB]

I have recently fully dismantled my stepper according to the Blitz method, cleaned and lightly oiled the screw pin with quality bicycle oil. Engine now seems smoother on tick over and 2000 rpm driving. Worth a try, costs nothing. Need a friend to help catch the pin when engine is started.

[blitzracing]

spitfire4v8 said:

You're right Mark i am fixing the symptoms but everything checks out. no leaks, road speed reads zero at rest, 37mph when moving.
What i'm fighting against is the stepper movement when lifting off the throttle .. the ecu automatically moves the stepper back and this is enough to add 1000rpm to the engine speed with no throttle applied. Only after coming to rest does the idle start to return to 1000rpm again.
I can't find any fault as such, it's just a symptom on this particular car that the stepper motion adds 1000rpm rather than 200-300 as per normal.
ive tried spacing the stepper rod (as youve done on your car) and restricting the stepper air pipe, but neither route works well for both hot and cold starts.
So i want to revert to an old fashioned idle control that blends the extra airflow out from cold start over several minutes.
ive ordered a bosch idle control valve and will see how it works.
Thanks for the replies.

That would tend to imply that the air feed hole the stepper blocks off may be damaged if you get a larger RPM shift for a set number of stepper pulses, so the calibration between the stepper movement and air control would be wrong.

[plasticman]

I am bound to have a spare one . I will look tomorrow .

[ChimpOnGas]

If there is no other induction leak check the speedo function & the connections at the back of the speedo, the output from the speedo to the speed control box is critical as is the correct function of the speed control box itself.