Help - My GU is a slug

Hoping for some straight advice, I've spent hours reading posts and trolling Google but I can't find any answers.

I have just bought a 2003 GU with the 3ltr Diesel and according to the plate running the RE4R03A HG43 trans/diff combo.

The car already has a 3" exhaust, upgraded turbo, safari piggy back computer running 17psi boost with dawes valve, stage 2 valve upgrades in the auto gearbox and runs 285/75R16's. The motor has just been rebuilt with oversize pistons and new heads 3000kms ago.

My problem is it's so damn slow and although I haven't tried would struggle to reach 120kph.
On the highway the cruise control is useless with the vehicle constantly hunting gears which makes the system unusable,
It will not sit in 4th let alone overdrive if there is any type of rise or head wind so sits in 3rd holding massive RPM's - 3750ish! Driving without cruise you can hold 4th but not overdrive if there is any upslope or head wind

Help, I know these aren't designed to be racecars but this is crazy, surely it isn't normal?

I'm thinking that diff gears may need changing to 4.6 to help with acceleration but I'm really concerned about the top end by doing this?

The car is completely serviced including gearbox/transfer and diffs.

Advice or comments appreciated

No 3 litre guru but MAF sensor can be a common culprit and a good place to start.

Sent from my SM-G930F using Tapatalk

As above Plus an intro would be nice... polite and all.
Are you still running OE intercoler if so if it oily
its leaking buy a tigged one from say Diesel smart.
Maybe go get a dyno

Sorry Threedogs, you're correct that was rude so let me start again.

Hey all, new to the forum and to patrols.
I live in the SW of WA and have just sold a D22 and bought a GU wagon.
Previous to the Nav I owned an 80 series with the 1HZ.
I bought the little Nav due to work commitments but the family has just outgrown it. I wanted another toy to get back into offroad driving and had this GU come up which has all the fruit and fitted the budget.
The car has a 4" medium rate dobinson lift, brand new motor (rebuilt due to a previous owner having replaced the heads and getting silicone and gasket gunk through the radiator causing it to overheat) Full aftermarket suspension, larger aftermarket intercooler and as stated in my first post lots of upgrades to the engine and gearbox. The guy I bought it from has receipts for about 15K worth of upgrades/motor work. (Pretty sure the MAF is brand new too as I have a spare in a plastic bag I found in the car)
The car has no leaks anywhere, perfect interior, rear draws, roof console, pod gauges for EGT's, Boost and dual battery charging, full lenght ali rack, General grabber AT's, rear LED work light, front LED spots upfront and a couple of well placed bush pinstripes. It's been built to play and I can't wait to get it into low range. I plan on adding a lightbar to the front and hardwiring a compressor and tank as soon as I get time.

Hope to be around here and get to know a few of you guys and tap into your knowledge of these vehicles.

Kind Regards
Silatman :)

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welcome to the forum mate,where abouts in the sth wst are ya?

You'll find in all states I think that a 50mm lift and 285 or 33" tyres are the limit.
Nice looking Patrol same colour as mine. Do you know what boost you are achieving?
No boost no go.....still thinking MAF remember even a new MAF can be fauly,
try and swap one with a mate first, if you need one give @mudski a PM

Could be the MAF. Is it the original intercooler on the Patrol? If so, is there any oil deposits on the core of the cooler? Are you running a needle valve with the Dawes? If not, a needle valve would be ideal to instal as the needle valve controls turbo spool up. Does the motor hold the 17psi max boost?

No need to change diff gears .... i would fix the underlying problem first which will be MAF or Boost.

I would think with the modifications listed that the boost should be slightly higher than it is now.

I would also look at disconnecting the chip, to put it back to standard to see if it makes any difference. I have heard through the grapevine of some Safari Chips not working as advertised .... i must say though, mine was always fine when i had it

I'm in Mandurah born and bred :D

I know she's a tad on the tall side but I love the stance (and the look of the whole car) if the local boys in blue take offence to her then I'll drop her back to legal at that stage, until then though........

The boost is set at 17psi and holds perfectly, I'm not sure if it has needle valve with the Dawes, is there any way to tell?

No the intercooler has been changed to a larger aftermarket top mount, I'm not sure what make but it isn't original and it isn't old.

I've just traced the manufacturer of the safari chip system who tells me there is no one in WA that can read the tune or make any changes, does anyone here know if that is true as I'd love to know what tune is in it and what it has been set up for?

I will put the other MAF I got with the car and see if there is a difference, I'll report back

Cheers :D

I will keep my eye out for you. I am based in Halls Head. :)

Checked out the MAF this morning and found it to be just placed in and not bolted in, looks like the top hole has been striped so i will need to tap it out to 6mm and bolt it in properly. I am not taking chances and will take the intake pipe off to ensure I dont get any pieces of plastic through the engine so it will have to wait until Saturday :(
I'm going to change the gearbox fluid to full syn at the same time and hope it makes a difference to the way it changes and runs.

The MAF did vary on the multimeter though and seems to be throwing correct voltage from what I've researched, it idles at 2.1v (EGR mod done) and revs to just over 3v at 3000rpm (can't remember exactly now)

I did find and play with the needle valve today too which probably isn't a good idea since I'm having dramas anyway, but I can't help but fiddle with stuff I really shouldn't. It seems to have a big flat spot around 3000rpm now but I'm not sure if I caused it this morning with the needle valve or whether it has been there all along - I really am my own worse enemy........
I will change the fuel filter and put the needle valve back to where it was, get the MAF bolted up correctly, do the gearbox service then see what happens from there :)

Cheers for the help guys.

Unplug the chip and then re assess I think.
As for the needle valve. We know your boost level is good, wind the needle valve right in while the engine is at idle, the arm on the turbo actuator should go up. Then slowly open the needle valve, until the arm drops maybe 5-10mm, 'ish, then go for a drive. If the boost rises real slow upon acceleration, the needle valve is open too much. You want the boost to rise quick and hit the max boost and stop. If it bounces a little past then settles. That fine. Alos at 100kph you would want around 12psi whilst cruising along the flat. if its lower and you want to raise this level, close off the needle valve a little. Vice versa if you want to lower it.