Outer Limits 4x4 Board

Can someone please tell me what size "tool" is required to adjust the butterfly stop on the intake of a 3.9 v8 . out of a 91 rangie . Its the one that sticks up stopping the throttle body opposite to the throttle position sensor .

I am guessing its an allen key but either its dam small or the one the right size I have is too long to get in under there . To save me cutting them all down does anyone know what size it is , if it is an allen key , in fact .

Been sitting on the engine for the last hour or so tring different ones . Only thing left is to bring my mirror home tomorrow and have another look at it .

Also if it gives me thins much grief can it be wound out all the way and put in the other way up so the adjuster is on the top ?

Isn't the idle speed set by the computer? In which case your throttle position sensor is having problems, or one of the other sensors/meters is cactus.

When mine was playing up, it was the dreaded air flow meter.......

If I get the idle adjusted the standard ecu is out the door .
The iacv regulates the idle , with that blocked of as per the manual when chacking the idle I can get no more than 500 rpm .

Need to open the throttle body a bit , so I can get some adjustment with the idle ajuster etc .

Cheers

Chris

Maybe some are different but on my 92 3.9 I am sure there is an air bypass adjuster on top of the throttle body which should be used to set the base idle.

This is near the vacuum advance outlet to the rear of the throttle body right on top. To get more air you just screw it out a bit. base idle should be 500-550RPM
Make sure the throttle blade is clean and the oil vent area is clean.

I know on a Thor 4.0 its a PITA as the stop is under the throttle body as the Motronic fully controls idle so there is no bypass. I think its a 5MM allen key on a Thor.
regards Philip A

Yes there is an idle adjustment on the top . With this fully out I am not getting enough idle .

I need to open the throttle body a bit .

Cheers

Chris

To adjust base idle on a 3.9 EFi, first remove the plug on the top throttle body/plenum chamber. It's near the accelorator cable conection area. Under the plug there is a grub screw . Use an allen key to screw it.

To set the base idle, you first have to disconnect and blank off the vacuum hose that leads from the throttle body to the IAC body. (It's the 1'' thick hose at the rear) Landrover have a special stopper hoses for this, but you can use a piece of dowel and 2 hoses or do what I did, use a couple of pieces of heater hose wrap some plastic insulation tape over the ends a few times to seal them and plug one end onto the throttle body conection and one on the IAC body.
Then start the engine, you might need a hand as the vehicle will want to stall. Get it running and adjust the grub screw till the base idle l is to specs. Then switch off and reconnect the original hoses back.

I believe I have seen sidecutters used to grab the head of the throttle stop, and turn it, but you have to be careful not to butcher it... Dunno if theres actually a proper tool....

Not quite sure what you mean by putting it the other way round though? The stops I have seen are screwed into the plenum? Is that what you are playing with, or are you adjusting something on the part that moves?

Hows the Megasquirt setup going other than that?

With the theft of my laptop the megasquirt has had a bit of a stall . Put have a mates laptop now so setting it back up again . Just need to get it idleing and I can take it for a drive and work from there . The borrowed laptop does not have a battery and only just got a cig liter power adaptor today hence the renewed enthuseasim .

Looks like know one knows what is used to adjust the stop screw . I have tried giving it a tweak with pliers from the top put its pretty firm . Will bring some tools home from work and try again tomorrow night . Get my mirro and look under there and see what it is . May just have to sacrafice it and use some vice grips . May be able to file a flat on each side .

Yep the stop screw on the plenum . I was thinking if its just a straight stop screw it may wind all the way out , then I could turn it up side down and wind it in from the top so you could get to the insert to adjust it again . Once its back in the middle I will be able to fine tune with the idle adjuster everyone goes on about so will not have to move it again so probably not worth getting it out .

Was really hoping someone had one off an engine they could look at but guess not .

Cheers

Chris

3/32 Allen Key, long one, or pliers from the top

Have you blown through the bypass with some WD40 or Carb cleaner? I would try that before mucking around down below.
regard s Philip A

Well can now confirm its a 3/32 allen key to adjust the butterfly stop .
What a prick of a job , me being short and the rover lifted I had to neal on the engine etc , usual blood loose .

But on the up side I now have an engine that idles at 900rpm with the iacv blocked off and able to alter the idle on the adjuster screw . I would say my iacv must be stuffed or sticky as with an unblocked valve it sits at 1200 rpm

Still that is not needed with the megasquirt so boo hoo . Back to tuning the idle on teh megasquirt tomorrow night , then some hooning down the road in the weekend maybe .

Cheers

Chris

good to hear you got it sorted....