Builds Ikarus' HDJ81 Aussie-Style Build (4 Viewers)

[mudgudgeon]

BACS is the Boost Altitude Compensation System. It uses vacuum (or the lack therof) to alter the movement of the boost compensator to decrease fueling when over 4K feet in elevation.

So I'll just run constant vacuum on BACS, simulating lower elevation, giving it more fuel, and tune accordingly.

Why not remove the BACS vacuum line completely.
Running constant vacuum, you've effectively rendered BACS redundant, and you're tuning from one baseline with the boost compensator function.
My thoughts would be, remove the vacuum line completely, you'll achieve the same thing, but remove a potential failure point.

If you travel to sea level, fueling may be a bit lean which means lower EGT.
I don't think you'd be down on power as fueling would be the same, but you have denser air.

And the question of the day is... my rear seatbelt buckles are backwards. How would you turn those around?

Fold the belt across itself length ways at a sharp angle, and work the folded belt through the buckle.
5 minutes, tops.

 

[mudgudgeon]

And the OEM boost sensor over here -

If you have a boost gauge, the boost sensor doesn't contribute much IMHO

 

[mudgudgeon]

In relation to above, not sure if the BACS has a bellows on the compensator rod?

HACS has a bellows that is affected by atmospheric pressure, and acts in a similar way to BACS, but without a vacuum line

 

[ikarus]

Instead of getting behind and attaching nuts, why not use rivnuts?

Oh smart, I didn't even think of that. Good idea

Why not remove the BACS vacuum line completely.
Running constant vacuum, you've effectively rendered BACS redundant, and you're tuning from one baseline with the boost compensator function.
My thoughts would be, remove the vacuum line completely, you'll achieve the same thing, but remove a potential failure point.

If you travel to sea level, fueling may be a bit lean which means lower EGT.
I don't think you'd be down on power as fueling would be the same, but you have denser air.




Fold the belt across itself length ways at a sharp angle, and work the folded belt through the buckle.
5 minutes, tops.

That's a good idea. I've heard that the pumps with BACS have a stiffer spring on the fuel pin so the theory is that the BACS vacuum helps pull it downward. But yeah it would be ideal to just remove it and tune from there. What do you think - just leave a vacuum line vented to atmosphere attached to it?

 

[ikarus]

Fold the belt across itself length ways at a sharp angle, and work the folded belt through the buckle.
5 minutes, tops.

Took about a minute. Easiest thing ever, I feel stupid for asking. haha. But that's what my build thread is for, for me to ask stupid questions

 

[duece71]

Working on placement of boost sensors. Removed the cowl to get better access - this is my favorite tool for this kind of limited access:

Pretty clean underneath, but the wiper linkage and bolts are pretty rusty:

I'm thinking I'll drill holes here since I can get behind and attach nuts and washers on the other side, and mount my boost sensor here -

And the OEM boost sensor over here since the existing wiring can't reach too far -

Or maybe I shouldn't bother about that one since I'll be overboosting all the time when I upgrade the turbo one day? Not sure.

Other than that, started working on the interior-

Tons of cleaning to do.

I'm going to pressure wash the carpets this week, got quite a few stains.

Found at least one open plug

And this purple mystery wire connected to nothing up front and an easy splice on the taillight loom. Took that out.

The last JDM wiring I need to remove is the Active Vacation power supply that went to the back. Looks like it T's into something under the steering column.

Removed the rear heater. I should have removed the hard lines when I had my exhaust off.

Checked on the blower under the glovebox. No debris but very dusty.

And the question of the day is... my rear seatbelt buckles are backwards. How would you turn those around?

Looking good, I want to tear out my interior at some point but not until I have a new stereo and speakers lined up for install. Now that you have the interior out, are you going to install some noise reduction foil? I have 3 packs of noico ready and waiting. Re your mystery purple wire…..I have a red wire connected to the right terminal of the left battery. It snakes all the way back to the tail and I figured it was some sort of ground wire. The 2 boxes have “short stop” printed on them. I am hesitant to remove this wire unless I know exactly what is going on with it.

 

[ikarus]

Looking good, I want to tear out my interior at some point but not until I have a new stereo and speakers lined up for install. Now that you have the interior out, are you going to install some noise reduction foil? I have 3 packs of noico ready and waiting. Re your mystery purple wire…..I have a red wire connected to the right terminal of the left battery. It snakes all the way back to the tail and I figured it was some sort of ground wire. The 2 boxes have “short stop” printed on them. I am hesitant to remove this wire unless I know exactly what is going on with it.

View attachment 3382260

Yeah, you'll have to trace that back and see what it hooks up to. Probably power cable for some sort of aftermarket accessory?

 

[ikarus]

This is how the rear hose bypass turned out with all OEM parts:

You can see the rear heater lines. Might cap them off just so it's a little more clean.

Got a lot of deep cleaning to do. Just ordered a new shift boot/seal as well since this one is torn:

Subwoofer was long gone and crumbling. Pulled it out for now:

So much potential room in there. I'm interested in that Wit's End quarter panel mount. Anyone else making something like that?

I also found two more small spots of rust I need to take care of before putting everything back together. These are under the rear door weather seal:

 

[duece71]

My subwoofer looked exactly the same. Removed it and into the trash. I kept the mounting bracket for just in case.

 

[ikarus]

1770517010 showed up and the intercooler pipes now fit perfectly.

 

[charlay61]

Did y

Spent a lot of time today reading up on the EGR system, BACS and SICS.

According to what I've read:

BACS is the Boost Altitude Compensation System. It uses vacuum (or the lack therof) to alter the movement of the boost compensator to decrease fueling when over 4K feet in elevation.

SICS is the Startup Ignition Control System. It similarly uses vacuum to deliver less fuel when starting up, for less smoky starts.

So I've decided to remove everything including the BACS and SICS VSVs. I live at 6K feet and mostly travel/wheel around 4K-10K feet. So I'll just run constant vacuum on BACS, simulating lower elevation, giving it more fuel, and tune accordingly. For SICS, I'll also plug in constant vacuum so it gets full fuel all the time.

In theory this should work. We'll see when I finally start it up in a couple weeks. @Rock40 had success with this setup in his epic 1HDFT conversion that I read through today:

Builds - Euro 1HD-FT Turbo Diesel/H151F 5 Speed Manual LHD 96' USA Swap

I believe the title says it, I'm going to begin a 24 valve 1HD-FT turbo diesel and matching 5 speed manual transmission swap into a USA model 1996 FZJ80 truck. A little background first: I've owned the 96' FZJ80 since January/2014 and it's been sitting in my shop ever since while I've...

forum.ih8mud.com

And on the Australian FB groups, those guys have removed everything. I love how simple the setup is.

The last VSVs:

New vacuum line:

old vs new

Recreated some of the stock setup - this is the vacuum pump segment:

Salvaged some T's from the old crossover setup. I'm going to have the line from the vacuum pump run up here, then T into two hardlines that cross the intake manifold:

SICS is the canister closest to the engine. BACS is the vacuum port in the middle hidden by the fuel line. Top is the boost comp cap.

BACS and SICS plugged into the two vacuum hardlines with new hoses:

I'll most likely run the boost comp cap up to the third hard line, then around the intake elbow to one of the brass fittings.

Not much I can do with all the extra wiring short of dismantling the entire harness. I'll just have to zip tie it out of the way or something -

But overall I love how much cleaner and more simple this is getting.

Before:

After:

Did you try the engine after removing all of that ? You hdj81 must have an emission ecu juste like Mine. The emission ecu controls all of the vsv's but also the intake heater. It also copies the rpm signal from the injection pump and resends it to the cluster. As much as i wanted to take everything appart, i had to leave a few bits in.

The emission ecu reads the boost pressure via the pressure sensor, however, the emission ecu also checks the vaccum also via the pressure sensor. To do so, it actuates that vsv's near the pressure sensor. It is switching the line from pressure to vaccum at idle and also preriodically at lower rpm's.

If you take that one off, or modify anything that will prevent that from working, after 10 seconds of engine running or so you will get the glow plug light to remain on because it indicates an error code in the emission ECU. The intake heater will will work as usual upon startup, but you will constantly get the annoying light later on when driving.

Also, the emission ecu does not care for "open circuits". Unplugging the vsv's won't be detected by the eecu. But surely it expects to read a good vacuum when the vaccum/boost vsv is switched and boost when it's not.

I wanted to take everything out on mine, but unfortunatly i had to keep that very vsv for the p-sensor along with the little oil fumes filter and a couple of vac lines.

 

[ikarus]

Did y


The emission ecu reads the boost pressure via the pressure sensor, however, the emission ecu also checks the vaccum also via the pressure sensor. To do so, it actuates that vsv's near the pressure sensor. It is switching the line from pressure to vaccum at idle and also preriodically at lower rpm's.

If you take that one off, or modify anything that will prevent that from working, after 10 seconds of engine running or so you will get the glow plug light to remain on because it indicates an error code in the emission ECU. The intake heater will will work as usual upon startup, but you will constantly get the annoying light later on when driving.

Also, the emission ecu does not care for "open circuits". Unplugging the vsv's won't be detected by the eecu. But surely it expects to read a good vacuum when the vaccum/boost vsv is switched and boost when it's not.

I wanted to take everything out on mine, but unfortunatly i had to keep that very vsv for the p-sensor along with the little oil fumes filter and a couple of vac lines.

Great to know, thanks for sharing.

So why did you have to keep the VSV for the pressure sensor and oil fumes?

Is the constant glow light the only downside to removing everything?

 

[kgrove]

Very cool build! Do you by chance still have the JDM door window visors? I'm into weird JDM stuff like that

PM me later. I won't be home for a week or so, but I think I have a set I removed from another HDJ81 in my garage I could sell you.

 

[kgrove]

I'm not sure, PO installed them. I should have looked for a model number but the tags were a little torn.

I would guess they're the 2.5" lift no load:

Dobinsons Direct

Dobinsons Direct

www.dobinsonsdirect.com

Late to the party, but I think you got the springs right. Here's the detail from the original order on your suspension parts:

Front Springs: C59-166 - Linear Rate - 2.5" with Stock front weight
Rear Springs: C59-167 - Linear Rate - 2.5" with up to 220LBS
Steering Damper: SD59-824 Big Bore Steering Damper (Included)
Front Caster Correction and Bushing Options: RB59-522K - Rubber Caster Bushing Kit 2.5 Degrees

 

[ikarus]

I removed the Active Vacation wiring. It consisted of 2x positive leads, a fuse, and a ground. It led under the carpet all the way to the front where it appears to T into a jumper between the ignition switch and the main wiring harness.

It plugged in here - ignition switch on the right in white, harness on the left in black. At first I considered jumping the black/yellow cable on the Active Vacation mini harness but then I realized that the entire mini harness isn't needed, as the EWD shows the ignition switch plugging straight into the main harness. I think this was just an Active Vacation add-on.

I removed it entirely and plugged the ignition switch into the main harness. Anyone replaced their ignition switch recently and can confirm this is right?

Working on the headliner. It's dirtier than I thought it was:

Not going to be perfect but it'll look a little better. I'm just going with the "light spray on the microfiber and scrub" method to avoid soaking the headliner.

Little gas cap door cleanup:

Steering shaft dust seal, long overdue:

Fender apron/liner cleanup. Some clips were falling out and the middle one got ripped.

 

[logicbyondreaso]

I removed it entirely and plugged the ignition switch into the main harness. Anyone replaced their ignition switch recently and can confirm this is right?

Yes - That is correct. Just clicked my ignition switch back together yesterday after the interior/HVAC refresh project.

 

[ikarus]

Continuing to slowly work on the intercooler install. Got the airbox in - just waiting on 2 vacuum caps for the airbox lid. Plugged the PCV inlet with an HPS 5/8" coolant cap -

The AC line bracket on the driver's side was contacting the IC pipe so I cut it down. It just barely clears now but should be good:

The middle support on the trim piece under the grille hits the IC so I chopped that off:

But I still have some issues with that trim piece now contacting the silicone piping on the wings. I have some more cutting and figuring out to do. PDI said to bend those tabs with the holes, which I tried, but I need to trim even more material off.

The cuts aren't perfect but I'll clean them up. Overall, not too bad. Even my turn signals fit pretty well which is a concern with the pipes on the PDI kit. The passenger side is sitting on the turn signal and pushing it out a little...

 

[ikarus]

While I had the cowl apart I figured I'd refresh the wiper linkage:

The nut for the wiper motor arm is somewhere in my engine bay or cowl, RIP

Working on refreshing the shifter assembly:

I wanted to dig into the sunroof console as it was sagging pretty bad - (ignore the mismatched screws, I just put that in upside down so I didn't lose it)

Screws were getting stripped so I replaced those -

M6x1.0 65mm

I found out why the console was hanging down in the back, the two other screws here weren't screwed into the roof.

Buffed out the altimeter plastic a little with some PlastX. Turned out nice

 

[mudgudgeon]

Fender apron/liner cleanup. Some clips were falling out and the middle one got ripped.

Ih8you! I can't unsee this now!

 

[ikarus]

Ih8you! I can't unsee this now!

I need to see if Partsouq has an influencer program!