Jackaroo 3.1 butterfly valve

[Roadrunner]

Hi everyone, I just bought another Jackaroo, a 1992 3.1 , and this one has a few small differences to my other jackaroo even though they are both 92 models. The new one has a butterfly in the inlet pipe that goes into the intercooler and I'm not sure of its intended function. I'm guessing it's a part of the quick warm up system, and was wondering if there is anything to be gained by locking it open so that it doesn't impede airflow through the engine. I don't really want to molest the car as it's all original but I don't live in a particularly cold location so don't think that I would ever have to use it.

[geeves]

Its actually part of the overboost system. You get too much boost and the valve in the manifold opens plus this valve closes to restrict flow. If its working and you are not looking for ultimate performance I would leave it alone

[Roadrunner]

Its actually part of the overboost system. You get too much boost and the valve in the manifold opens plus this valve closes to restrict flow. If its working and you are not looking for ultimate performance I would leave it alone

I don't know if it works or not Geeves, maybe I should fit a boost gauge just to get an idea of the "normal" boost figures, but that's where it starts, then I might be tempted to screw in the fuel screw a half turn, it must be a sickness, sort of like a compulsive behaviour thing where I'm unable to stop myself from tinkering in the search for "just a few more H.P.'s"
I'm going to leave it alone for now, I'm not sure how long I will be able to hold off though!
Thanks for answering, you probably deserve a coffee or 2 for your efforts over the years!

[geeves]

thought the fuel screw was turned out. Also check the position of the diaphram in the boost compensator first as it can have more effect

[Roadrunner]

thought the fuel screw was turned out. Also check the position of the diaphram in the boost compensator first as it can have more effect

You're most likely correct on the fuel screw, I tend to forget some of the details, I'm not going to touch the fueling for as long as possible, as I don't want to have ANY visible smoke coming out of the exhaust pipe, and have decided that a small 9 inch fan mounted onto the intercooler along with a cold air induction pipe for the airbox inlet is about as far as I want to go at this stage. I'm not even going to take it off road because my high mileage jack is more suited for that type of use.

[paulthepilot5]

You sure it’s not EGR related? Many systems have butterfly valves set up as part of the EGR recirculation.

I would just remove it and blank off EGR if it has that too. One less thing to fail and hamper performance.

[Roadrunner]

You sure it’s not EGR related? Many systems have butterfly valves set up as part of the EGR recirculation.

I would just remove it and blank off EGR if it has that too. One less thing to fail and hamper performance.

I don't think so, unless it uses an internal egr system, which is possible because I still haven't figured out exactly what the butterfly in the exhaust pipe does yet. I'm thinking that the exhaust one might close up when coasting with no throttle, acting as an engine brake of sorts because it does slow down quicker than what my other jack (which has no butterflies) does. There aren't any egr mounts on the intake manifold, if there were I would blank them off. Both butterfly valves must be a part of the quick warm up system, there are around six small vacuum/pressure rubber hoses that go to about 3 small electrical thingys up near the brake booster, Anyway, I'll work it out eventually.
I turned up the fuel screw and rotated the boost compensator diaphram a few days ago, couldn't help myself
I also took the 2 rear child seats out and took the spare wheel off the back door, which took around 100 kg off the weight of the car, I'm not too concerned about getting a flat tyre because I'm running A.T./s which are so much better than normal street tyres as far as durability goes. I also screwed on an intercooler fan which runs anytime the ignition is on, it makes a noticable difference when running around town at lower speeds. Oh, I nearly forgot to mention the lightbar, it is a cheapie (around $60. at Autobarn, but I found it for $40. online after I bought it. Single row of led's, about 20 inches long and only takes 70 watts, it beats the HID's I had on my other jack by a country mile, turns night into day!