Land Cruiser Prado 90 RZ Import & Refresh (and maybe build...)

[JDM Journeys]

I'd be leaning towards electrical. Have you queried the onboard ecu? There's a diagnostic port under the hood. Be interesting to see if there are any codes...

Are we sure the fixed ECU is 100%?

 

[apexwerks]

I'd be leaning towards electrical. Have you queried the onboard ecu? There's a diagnostic port under the hood. Be interesting to see if there are any codes...

Are we sure the fixed ECU is 100%?

No codes, I should have included that- good catch.

No, unfortunately I'm not sure. There was one capacitor obviously leaking and we replaced it, but left the others be. There might be more damaged components that just haven't let their guts go. The solder is high temp and the guy that helped me was worried about damaging the board, so he only did one.

I adjusted the spill control valve and the throttle cable tension, no change. I have noticed that if the A/C is off, the engine is fine. Makes me think you're right about something electrical... there's clearly two throttle circuits (in gear and out of gear) and the in-gear circuit isn't raising idle to accommodate.

 

[apexwerks]

Looks like I was wrong… the A/C didn’t solve the issue. Just happened to try it when the issue wasn’t occurring.

Here’s a video of what I’m getting:

 

[JDM Journeys]

Looks like I was wrong… the A/C didn’t solve the issue. Just happened to try it when the issue wasn’t occurring.

Here’s a video of what I’m getting:

Wow. That's very erratic. Hmmm.

Wish we had a member close by with same rig who could volunteer their ecu for a test run. But even for a next door neighbour that's asking a lot. Wonder if there are procedures in the fsm to test the ecu for full functionality?

 

[apexwerks]

I may have a solution. According to the FSM, the resistance across the spill control valve is supposed to be 1-2 ohms. From what I've read, actual target for the sensor is 1.4 ohms. I'm reading 17.5 ohms, so it looks like the coil in the valve has gone bad.

Now I just need to see if I can source a new one quickly... anyone have any ideas where I can locate one in the states?

 

[apexwerks]

Found a spill control valve... it's on the way from an eBay seller. If it solves the issue (which I very much hope it will) I'll put together a DIY post to show how it's done.

Blackstone got the oil analysis back today. They noted increased iron in the sample, but the key finding is no coolant in the oil. Great news, and means the head is in good shape.

 

[JDM Journeys]

Two thumbs up for the head, and another for the SCV when it fixes what ails her.

 

[apexwerks]

Well, I'm very glad I didn't wait for the spill valve to arrive before I left for the 70-series meetup. That would have made for a frustrating day and a very late night. We took the GX instead and had a blast- thanks again @Gun Runner 5 and everyone else for such a great event!

The fuel spill valve arrived while we were at Windrock, and I got it installed yesterday afternoon. The new unit tested 1.6 ohms resistance out of the box and by all indications was a genuine Denso unit.

Cut down a fan clutch wrench for the install, got it installed and hooked up in less than 30 mins. With the new unit to compare to, it's obvious the old FSV has been handled in the past. There's tool marks on the body, the cap on the adjustment screw is missing, and one of the tabs on the electrical connector is broken.

Got the new unit in and buttoned up, ...and then the truck wouldn't start. At all. I was getting a dribble of fuel at the injectors, but nowhere near enough to actually crank the truck. Adjusted the new valve, but still got just a dribble at the injector. Put the old valve back in and she fired right up. I used a heat gun and heated the old valve up to ~190 degrees F, to see if the coil was functioning correctly when cool but not when the engine is fully heated up, but even at that temp the behavior didn't return.

So either I got a bad unit out of the box, or it's back to the ECU as the culprit and somehow the bad ECU and the bad FSV are cooperating in a way that the new unit can't.

When I pulled the ECU the first time, there was a wire soldered onto the top side of the board. I thought it looked funny, but there wasn't really any indication that it had been tampered with or that the unit had been removed from the vehicle previously. I couldn't find a picture of the ECU from a 90 series with an A/T, so I shrugged and went on. Here's the pic from earlier in the thread, for reference... you can see the red wire in the bottom left hand corner.

Well, lo and behold last night some guy in Latvia had 2 1KZ-TE ECUs for a 90 series A/T up on eBay, complete with pictures. Here's the picture from his listing...

The numbers on the circuit board match, but there's no wire between those two diodes. Needless to say, I ordered one of the used ECUs the guy has post-haste.

Still not sure what conclusions to draw here. This must be the reason the truck was sent to auction in the first place, and I'm re-tracing some Japanese mechanic's steps in diagnosing the intermittent fuel starvation issue. I'm guessing someone jumpered between the two diodes to bypass part of the ECU board, and maybe made similar modifications to the FSV? If this was a gas engine, I'd be concluding that there was an issue somewhere in the closed-loop fueling that's not happening in open-loop mode. When the engine is cold, or when it's in park or neutral, I'm assuming it's in open-loop fueling and giving the engine a pre-calculated amount of fuel. Once it's good and hot it seems to switch to another mode that struggles to give the engine enough fuel? But for a gas engine, the "loop" is completed with O2 sensor data, which this motor doesn't have. So basically I'm lost.

But I do know the resistance reading on the new FSV is correct, and that red wire, whatever it's for, is not supposed to be on the ECU. Used ECU is on order.

 

[apexwerks]

Great news!

It was the ECU. You were right, @JDM Journeys. New ECU finally came in… eBay seller had it listed in Lithuania, but it shipped from the middle of nowhere Russia. Getting a package from Russia to the US is more than a little slow right now… I wouldn’t have bought it if I knew it was coming from there, but the good news is the unit I got is in great shape and resolved all the engine issues I was chasing.

Nice and clean in there! All the caps look great.

Plugged it in and the truck started right up. Drove it for almost an hour this afternoon and no stalling or other power delivery issues. Hallelujah! So this is what the 1KZ-TE is supposed to drive like? Much more power, more throttle response, much more enjoyable to drive. Suppose I had read so much about the 1KZ-TE being down on power that I didn’t realize this one had problems. It’s like a whole new truck now…

Still a few small items left on my punch list, including a new sunroof panel (more on that later), but it’s looking like the biggest issue stopping me from enjoying the Prado is resolved. What a relief.

 

[apexwerks]

Well, I think we successfully have the drivetrain and electrics stabilized. I've been daily driving the 90 for the last two weeks, and it's running and driving flawlessly. I can't help but wonder if everyone that's criticized the 1KZ-TE as being down on power and un-drivealble didn't have ECU issues themselves. I'm not doing any stoplight drag races, but it's perfectly driveable at modern highway speeds.

Anyway, I digress. Now that the mechanicals and electricals are good to go, we get to do more fun stuff. Should be a big weekend...

 

[apexwerks]

Drawers!

I had initially planned to take some time over the winter and build a set of custom drawers for the 90, but ended up deciding not to. I just couldn’t justify the cost and time… I scoped out materials and ended up north of $700 for the build I wanted, plus at least a few days of work. The Ironman 900mm drawers were $749 + $100 freight, and listed the 90/95 in the instructions. For $150, I’d rather have the drawers now and have that time spent building to do more fun things.

Ironman shipped quickly, and I had no problem with the freight delivery. The driver dropped the pallet on my sidewalk and it was a no fuss situation.

On the SWB, the rear seats need to be folded up and stowed, or removed entirely for the drawers to fit. I rarely have more than one person in the truck, and it’s simpler to fit the wheelchair with the seats up, so that’s not a great loss for us. I chose to just pull the rear seats entirely, to give more storage space. The drawers fit perfectly between the wheelwells and are exactly the right height- they were clearly designed to fit in the 90/95.

However, on the 90 at least, the sliding ribs did not line up with the attachment points. I had to remove the rear seat strikes, drill the floating ribs on the drawers, and make do for the rear attachment point. There are no front attachment points that will work in the 90, so I plan to use a turnbuckle on the rear-most D-ring. The other option would be to drill through the floor, and I didn’t want to do that.

The drawers ended up about 5” back from where Ironman recommend they be mounted in the 95. That was the closest I could get them without really hacking up the frame of the drawers, and given that the rear seat is out, I have plenty of space. This also gives me room to mount a table on the rear door, which I understand you can’t do with the drawers mounted flush with the trim.

The other nice thing about the drawer construction is the easily removable top panels. This allows you to mount a fridge slide on the workbench and then drop it in place, which saves a lot of awkward reaching to tighten bolts.

Final setup: I may end up swapping sides and moving the fridge to the left. The door on the Prado curves inward, and even fully open I’m getting some interference between the fridge lid and the top lip of the door.

I reached out to Ironman to request the wing kit be special ordered from AU, but now I’m second guessing. The SWB is so short behind the wheel wells that there’s really not much space left to fill. I still need to get turnbuckles and swap the fridge to the left. The door table should be coming in next week, and I’ll try to get it all knocked out at once.

 

[tip]

Excellent troubleshooting in this thread, way to stick with it!

Subscribed. I want one of these so bad.

 

[apexwerks]

Excellent troubleshooting in this thread, way to stick with it!

Subscribed. I want one of these so bad.

Thank you! We have had a ton of fun with it so far.

 

[apexwerks]

Next up… dual batteries.

I had initially planned to keep it single battery and use a power station or maybe a rear-mounted lithium with a DC to DC charger for the fridge, but the numbers are still heavily tilted in favor of a wet-cell lead acid battery. Plus I already had a voltage-sensing relay and a junction box, so that further reduced costs. We put the battery in the second battery location, behind the left headlight. I used a universal battery tray and modified it to fit.

The hardest part was re-routing all the accessory wiring and junction box I had in place on the primary battery. The actual install of the VSR and second battery were pretty easy. Walmart will sell you a 100 amp-hour battery for $79, and you just can’t beat it. Here’s the almost finished product- still need to trim some wire ties and button a few things up, but it’s almost there.

But, this means I had to relocate my compressor. I had installed it in the second battery spot under the hood, but was never super happy with the location. We were puzzling over where to put it… until while I was running the power line for the rear junction box, I happened to notice that there was a large pocket of empty space behind the passenger side B pillar. It’s *exactly* the right size for a single-cylinder ARB compressor to fit into. You have to remove the rear interior trim panel (there’s one large panel that runs from the rear door to the front) and behind/beside the seat belt reel there’s a large empty space. It’s hard to get a great picture of, but if you pull the interior trim panel you’ll see what I’m talking about.

I had some push-to-connect fittings and hose and a junction block left over from another project... the junction block and the power outlet for the fridge fits perfectly in the cup holder/storage area in the rear.

I’m pretty happy with how it all turned out.

 

[apexwerks]

We also got a tailgate table installed this weekend. We ordered the smaller size table for the Prado 150 from Kaon. The dimensions online looked like they’d fit the 90. Don’t think I’d do it again, though… we made it fit, but it’s a little kloogy.

There’s apparently less sheetmetal behind the door card on the 90 than the 150, so placement options are little more limited. If you put it on the left, there’s plenty of room, but that means you get interference between the drawers and the table.

In order to have enough metal to attach it to on the right, you have to shift it all the way to the right edge of the door card. That gives you a little interference with the door seal on the right, but not so much the door doesn’t close. I did trim the edge of the table a little to get the clearance better.

The Kaon table is the perfect size for my stove, and the fridge slide and the drawer will fully extend without interfering with the table.

It’s a little kloogy and I would probably put the time into making a plywood table that fit vs. hacking on this one to make it fit.

 

[apexwerks]

Well, I hadn’t initially planned to install a wing kit to close the gap between the drawers and the body, but that didn’t last long. The space isn’t very usable without a flat platform. Also, without some kind of a lip on the back of the drawers, without the back seats in every time I touch the brakes, whatever I have in the back goes zinging into the rear footwell. Not ideal.

Rather than wait any longer on Ironman to decide if they’re going to sell me the wing kit for the 90, I took matters in my own hands. The tops of the drawers are just hardwood plywood secured by M6 screws, so we decided to just replace the whole thing with a single sheet of birch plywood. We used cardboard (from the Ironman box, natch) and a compass to scribe the contours of the interior, and transferred the pattern to a sheet of birch BSG.

Used the drawer tops as a drill template for the mounting holes…

And put in some L-track next to the fridge slide to secure loads.

It squeaks like a b*$tard and needs to be coated in bed liner, but it’s a lot more serviceable than the original configuration. More to come as we get all the wrinkles ironed out.

For no other reason than it’s fun, here’s a glamor shot from yesterday:

 

[apexwerks]

In-laws are due in this afternoon, so I had to get the platform wrapped up so I could get a car back in the garage.

Not too much to report here… after many challenges earlier in the project, the final stage just came together. We used Rustoleum bedliner in a can, and a trimmed down piece of aluminum stair nose for the back lip.

I really like the L-track… got it from an outfit called Mytee Products. Inexpensive, fast shipping, good quality.

After the in-laws are headed out, I’ll take it out for a drive and see if we sorted the most of the squeaking and rattling.

 

[apexwerks]

Does anyone have any suggestions on roof platforms? Getting some space to put things on the roof is next on my list, but I have very limited garage clearance. As it stands today, I have 3” between the top of the factory side rails and the garage door. We’d like to get a setup in place that doesn’t require removal of the racks or deflation of the tires to get it in the garage. The Smittybilt Defender is 4” tall, so that is a no. The Frontrunner slimline looks like it should clear, but it’s over $1k.

My goal is to be able to mount a batwing awning and some lights, primarily for camping. It would also be nice to put some bulkier items/wet or dirty items on the roof from time to time. I suppose we could just do crossbars and use a coffin box that we remove to garage the truck, but that would limit light mounting options. What do you folks think?

 

[javelinadave]

Does anyone have any suggestions on roof platforms? Getting some space to put things on the roof is next on my list, but I have very limited garage clearance. As it stands today, I have 3” between the top of the factory side rails and the garage door. We’d like to get a setup in place that doesn’t require removal of the racks or deflation of the tires to get it in the garage. The Smittybilt Defender is 4” tall, so that is a no. The Frontrunner slimline looks like it should clear, but it’s over $1k.

My goal is to be able to mount a batwing awning and some lights, primarily for camping. It would also be nice to put some bulkier items/wet or dirty items on the roof from time to time. I suppose we could just do crossbars and use a coffin box that we remove to garage the truck, but that would limit light mounting options. What do you folks think?

I woke up this morning thinking about this very same thing. I may make a roof rack that fits inside the factory rails using this stuff. Tap threads into the ends and mount it up to a piece of flat stock and somehow attach that to the current side rails. The cross bars on my Prinsu rack on my Tacoma are made of the same stuff.

 

[apexwerks]

I woke up this morning thinking about this very same thing. I may make a roof rack that fits inside the factory rails using this stuff. Tap threads into the ends and mount it up to a piece of flat stock and somehow attach that to the current side rails. The cross bars on my Prinsu rack on my Tacoma are made of the same stuff.
View attachment 3178335

I think that might be the way to go here. Best I can tell, even the Frontrunner rack will be too tall to clear the garage door opening.

On the 120 Prados, the factory side rails are bolted onto captive nuts in the roof, with the nuts hidden under some trim panels. If the 90 is similar, I wonder if we could just remove the factory side rails entirely and fab up some kind of bracket so we can bolt the platform directly to the roof.