GU Cruise Control Sensitivity

Hi all,

Thought I would fill you in on a simple issue that I've probably spent too many hours working on a fix. Since I installed my new fuel pump and turbo the factory cruise in the GU is way too sensitive, it over accelerates then over compensates in the other direction constantly. Makes you motion sick if you're sitting on the highway.

In my searching I couldn't find an easy fix, only people installing a whole new cruise unit. I don't mind a challenge and haven't needed to drive the patrol much so I really wanted to try and find a way to fix the factory unit.

I don't know if anyone will get any use out of this but I thought I'd share anyway. I've already tried a few things so I'll probably break it up over a few posts.

FIRST ATTEMPT:

Thought I'd start simple and hopefully kill two birds with one stone.

My speedo has always been out by about 10km/h so ordered and installed an electronic speedo calibration mod. I know you can change the little gear in the box but this probably took a similar time to install and now if I ever want to adjust it, it's super simple. It also has a sensitivity adjustment "sensitive" and "normal", i thought this might fix my problem as well

Attachment 82364

This fixed my speedo but not my cruise. (I need to come back to this one though because I just recently worked out that I think I've installed it upstream of the cruise unit.. ie the unit still sees the speed straight from the box)

SECOND ATTEMPT:

I read on a forum somewhere that someone had tried to make the lever longer for the fuel pump but they couldn't make it work because the cruise would auto cancel on them. I thought I'd have a go my self;

Attachment 82365

Attachment 82366

I chopped the lever off and replaced it with a bolt and lock nut setup so I could adjust it. Quick and dirty for a proof of concept.
To my surprise this actually worked! It just doesn't work like it needs too. It lowered the sensitivity but the vac diaphragm doesn't have enough stroke, works perfect anywhere under 100km/h but can't maintain 110km/h because it can't pull the throttle far enough..

Back to the drawing board.

THIRD ATTEMPT..kinda

At this point I've probably been dicking around with this for over 12 months when I found an hour here and there to spare on it.

I decided I had enough, conceded and got a new unit;

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After the box had gathered a suitable amount of dust I decided to open it up and start planning the replacement. I quickly worked out looking at the service manual/wiring diagrams that looked like there was going to be some teething problems. The factory steering wheel buttons/clockspring does in 2 wires what the aftermarket does in 3 or 4. I looked at the (shitty) instructions for a while and thought of a few ways around it if it wouldn't just plug and play. This kinda annoyed me a bit and pushed me back to having one last crack at fixing the factory unit..

Edit: to be clear I was aware when buying the unit "plug and play" was a relative term. My plan was just to use existing cruise control wires and splice them to suit the new unit.. but even this looked like it may have its challenges.

ATTEMPT 4 (in planning):

Attempt 4 brings me up to present day.

2 things I want to try when I next get the chance..

First revisit attempt 1. I want to run the output of the speedo calibration module direct to the cruise unit. See if this fixes it or makes any difference.

If that doesn't work I think I've worked out a way to use an arduino to modify the signal from the cruise unit to the vac pump while retaining all the factory safety features and cut outs. Essentially it'll just pulse the vac pump at a user adjustable frequency when the cruise control unit tells it too. I actually really want to try this out just for the sake of it..

Anyway, that's where I'm at for now. If someone knows a fix that would have saved me hours of my life, feel free to keep it to yourself.

Probably too late now but this is how I connected my factory cruise control to the pump when I did my conversion. It works well, same as it did on the TB45E engine.

Cruise is the lower cable in the pic.

Attachment 82369

Found a better pic

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Quote:

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Originally Posted by jff45

Probably too late now but this is how I connected my factory cruise control to the pump when I did my conversion. It works well, same as it did on the TB45E engine.

Cruise is the lower cable in the pic.

Attachment 82369

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Thanks for that mate.

I don't think my issue has been the connection although yours does leaver from a slightly different point. Mine was connected through the normal factory mount.. And it "works" fine it's just too sensitive and adjusts the pump too severely with the extra power since the pump upgrade.