Thread: idle bypass valve

Originally Posted by spook

thanks philp i will have ago at her tomorrow after work thanks for all the info thanks luke..

well i had ago at the truck and did what you said block of the hoses both ends well it would not idle at all, cleaned the butterfly it was dirty but still no idle,the butterfly im not so sure how to adust there is no screw to lift the idle, only thing is the allan key screw on top of the butterfly yes it does speed up the idle if i keep winding it out,but it does make a horrible sucking droneing noise when its idleing where i want it to idle, am i on the right track,thanks luke..

Yes you are on the right track. The screw opens and closes an idle bypass hole .

Hmm I wonder if you have something else happening. Maybe you had an air leak around the old stepper. It definitely sounds like someone has done something to compensate for another problem.

Just get it to idle without the stepper then turn it off and reconnect the pipes and see if the stepper works correctly.
Regards Philip A

Originally Posted by PhilipA

Yes you are on the right track. The screw opens and closes an idle bypass hole .

Hmm I wonder if you have something else happening. Maybe you had an air leak around the old stepper. It definitely sounds like someone has done something to compensate for another problem.

Just get it to idle without the stepper then turn it off and reconnect the pipes and see if the stepper works correctly.
Regards Philip A

ok thanks mate i will have ago again tomorrow afternoon it does have a kn filter on it which makes a bit more air sucking noise as well ,and the rangie always did idle a bit slow, thanks for the help luke.

Also ... if you having trouble setting the base idle ... check to make sure that there is no foreign material causing blockage in the bypass hole ...

Those pod filters are noisy .... make sure that all the air filter intake hoses are connected when adjusting / including the air filter / pod .... If you have the air filter off / not connected to the front of the MAF ... then it will not idle or run properly

Mike

Seeing you are working in the area, get some electronic contact spray and clean your MAF by spraying into the small hole you will see if you remove the screen. K&Ns are notorious for fouling 14CUX MAFs as the 14CUX is almost unique in not having a burn off phase.
Regards Philip A

Originally Posted by mike 90 RR

Also ... if you having trouble setting the base idle ... check to make sure that there is no foreign material causing blockage in the bypass hole ...

Those pod filters are noisy .... make sure that all the air filter intake hoses are connected when adjusting / including the air filter / pod .... If you have the air filter off / not connected to the front of the MAF ... then it will not idle or run properly

Mike

thanks for them hints i got it to idle with the hose blocked today and now runs with the stepper now and keeps idleing, only took it for a short drive but it did not stall,it runs about 500rpm when in drive and about 700rpm when in park so i will see how it goes tomorrow got the day off so i will be able to drive it ,i did have to screw that allan key in a bit it was makeing terrible droneing noise through the pod, thanks luke..

Originally Posted by PhilipA

Yes you are on the right track. The screw opens and closes an idle bypass hole .

Hmm I wonder if you have something else happening. Maybe you had an air leak around the old stepper. It definitely sounds like someone has done something to compensate for another problem.

Just get it to idle without the stepper then turn it off and reconnect the pipes and see if the stepper works correctly.
Regards Philip A

Phillip....

On the flapper models ... Ive seen an adjustment of the butterfly to be opened to a measurement, via feeler gauge ... There is a "steel stopper screw" adjustment under the throttle linkage

It is a "steel screw" that can can only be turned from the underside of the plentium

Should the butterfly (throttle plate) be fully closed ... or should it have a certain gap // holding it slightly open from the body??
(then adjust the base idle screw to achieve desired / correct "base idle")


I also realise that any adjustment of the butterfly has an effect on the TPS ... requiring that the TPS position be recalibrated to the correct "closed position voltage"


Mike

Just a point of note when setting base idle, make sure you set everything back to factory first, particularly the timing, which needs to be set to 2deg BTDC with vac disconnected.

This includes checking the throttle plate. A depth vernier is required to do it correctly.
Measure the depth of the top and bottom of the throttle plate against the plenum opening. the throttle should be within 0.5mm differential measurement. If out side this, adjust using the set screw under the plenum, but you need to take it off to do so.
DON"T DO ANYTHING UNLESS YOU HAVE CHECKED THIS FIRST as it will be a waste of time. You will only ever need to do this once unless you change plenum or install new throttle shaft so its generally worth the fart arsing around to do it.

If you havent modified your TPS to be adjustable this will be relatively easy, but if like me you have modified it and altered the position, you will need to check that at actual base idle, the TPS voltage is .33-.35v and this may require you to do multiple adjustments as the voltage change can add or subtract around 100rpm in some cases.
Actual adjustment to base idle speed is with the airbleed screw. Use a digitial tacho to check this, dont rely on tacho in dash.

Once you have done this, hook everything back up, adjust timing to 8-10deg BTDC, check TPS voltage, adjust MAF input voltage to about 1.3-1.5V and use the airbleed to adjust to where you want it.

Dont forget to check PCV hoses for vac leaks and breather for cleanliness.

After that, should be all good. If you still have issues, time to check fuel lines, injector blockages and the fuel and coolant thermistors, but thats another lesson.....

Cheers

Andrew.