Completed Project 93 Explorer TDI Swap

[BKennedy]

Performance wise I really like it so far. It has really good power delivery. Doesn’t struggle to get up to speed and over hills. It responds really well to the right foot!

With that being said I still think a re-gear is in order. First gear is kind of a pain and I find myself dancing between 4th and 5th when cruising 60 mph. A good set of 4.56s could only make this thing even better.

I think your 700r4 with 5.13s would be a great pairing for a TDI without having to change much else. Your first gear ratio is a lot better! A 2.0 CJAA out of a newer Golf or Jetta is a great starting point. They’re a common rail diesel and super easy to squeeze more power out of. There’s also a ton of them laying around from the whole “diesel gate” ordeal. I had also seen that someone was working on developing an adapter kit for the VW/Audi 3.0 V6 TDI. Not sure how well it would fit, but this would be an option to explore as well.

Take it out rock crawling, find a couple loose and steep hillclimbs and report back

 

[timtimtimajim]

I'd be interested in knowing what the solution is to make it run outside it's native environment.

I think for the 3.0 it should be about the same as the other four cylinder swaps. Transmission adapter, fuel system, and a standalone harness. The biggest part would be tricking the ECU to run in a different vehicle without certain modules attached.

Diesels have a low redline. I think it would make for difficult going when you need wheel speed in hill climbs, soft material etc.

That’s true, but also depends on how the engine is built. Mine redlines right around 2800. I’ve seen some TDIs that are newer and way more built with redlines closer to 4000.

Take it out rock crawling, find a couple loose and steep hillclimbs and report back

That’s the plan! Need to sort out a few more minor things first.

 

[timtimtimajim]

Time for an update I've been keeping quiet for a bit:

Right after Christmas I was over visiting with my parents. Left their place and got about 200 yards from their neighborhood and the Explorer shut off. Tried both the key and popping the clutch to restart, but no luck. Was acting almost as if it had ran out of fuel. Pulled off on the side of the road to check some things over. Had plenty of fuel and nothing showed as obviously wrong. Did not seem to be getting an engine speed signal. Unfortunately I didn't have a spare crank sensor on hand. Had the Explorer towed back to my parent's place (closer and easier to roll a dead car into the garage).

Was able to get a new engine speed sensor quickly. Swapped it in but still no start. Still acting like it was not getting fuel. Checked both the lift pump and tandem pump. They were both fuctioning correctly and pushing fuel. Pulled glow plugs and cranked but was not getting fuel out of the injectors/cylinders. The injectors in a pump deuce are cam driven and electronically controlled by the ECU

This sent me down weeks of troubleshooting and checking wires. Pulled back most of the harness to find either a chafed or melted wire. Still no luck.

Got to the point where I had to start checking EVERY pin on the ECU. This is where I started to find some oddities. First thing I found is relay latch signal from the ECU was marginal as far as what the relay needs to latch in order to send power back to the ECU to power up. The ECU relay would chatter before latching on. The second thing I found was the ECU was losing power when cranking. Checked over ignition wiring and even bypassed the ignition switch. Still nothing obviously wrong.

Pulled the ECU cover and started testing components on the board. Inside of the ECU smelled like something had burned. Found a couple burned diodes. Ordered and replaced the bad diodes but still had no idea what would have caused them to burn. This ECU also showed water damage in the plugs that is related to a recall on MKIV Jettas and Golfs. Plugged the ECU back in but still no start with ECU losing power. I could still communicate with the ECU prior to trying to crank.

After a lot of digging and the help of a VW mechanic I was able to find the entire troubleshooting booklet for a 2004 Jetta. This included full wiring schematics including the ECU board. What I found was that these diodes were on the main power into the ECU from the battery/alternator. With this I was able to determine that the voltage regulator on the alternator died and caused a huge voltage spike that killed the ECU. Looks like the regulator died because the charge light was pushing 12v to the regulator. In a Jetta the charge light is grounded in the dash and the ECU supplies 12v through the regulator to the light if there is a charge problem.

Had to order a new ECU. Got very lucky and found a brand new in the box ECU that had never been used and matched the part and calibration number on my ECU. These are getting hard to find as they are no longer produced. Also had to order both a KESS interface, a KTAG interface and a BDM frame in order to pull my Malone tune off of my old ECU and migrate it to the new one. The tune was pulled off of the original ECU without issues and showed no corruptions in the file. The new ECU took the tune with no problems.

Replaced the alternator with a new 120 amp unit. Replaced the ECU relay out of caution and added a mega fuse between the alternator and battery (there was already a fuse between the battery and ECU). Plugged new ECU in. First turn of the key the Explorer started briefly but sputtered and died. Lack of fuel from all of the cranking while troubleshooting. Second turn of the key and the engine fired right up and ran. Let the Explorer idle for several 20 minute stints with no problems. Looks like everything is working correctly now.

Still have a few things to button up. Need to reseal the new ECU as you have to pull the cover off to read/write tunes. Need to wrap the harness back. Also need to tune out some EGR and O2 sensor stuff on the new ECU.

 

[timtimtimajim]

After the whole debacle with the ECU I decided to reconfigure a few things. Wanted to move the ECU to a safer location that was also easier to get to. An hour or two on Solidworks I came up with this weatherproof box.

Almost eight days straight on the big 3D printer and we’ve got an ECU case.

I didn’t get a picture of the frame I built to hold the box and the three different fuse panels. The inside of the case has TPU dampers to help isolate the ECU from from vibration and to hold everything in place.

Final product after moving everything around. The top of the case turned out rough because of a printer setting that needs to be changed. Decided I don’t hate the look so just went with the rougher top.

Everything with the ECU has been sorted out now. O2 sensors and EGR stuff has been tuned out. No more check engine lights. Should be able to start driving it again.

 

[Josh P]

I like how it looks

 

[timtimtimajim]

Ditched the Autometer DashLink with my phone for a Scan Gauge II. Don’t like having my phone constantly hanging in front of me from the windshield. Mounted the Scan Gauge on the steering column. Feels more natural looking down at it.

The Explorer drives way better now. I think the original VW ECU was on the way out from the beginning. No more turbo stutter during the geometry change. Everything responds better.

 

[ItsLimesyyy]

Ditched the Autometer DashLink with my phone for a Scan Gauge II. Don’t like having my phone constantly hanging in front of me from the windshield. Mounted the Scan Gauge on the steering column. Feels more natural looking down at it.
View attachment 450893View attachment 450894

The Explorer drives way better now. I think the original VW ECU was on the way out from the beginning. No more turbo stutter during the geometry change. Everything responds better.

This thread is giving me dangerous and wallet hurt-y ideas...Amazing work though!

 

[Rick]

How did this turn out? Is it being daily driven? Any time spent offroad?

 

[bats]

What a bad time to find this thread. My BII has an empty engine bay and is already setup for a M5OD.

 

[timtimtimajim]

How did this turn out? Is it being daily driven? Any time spent offroad?

It’s been working great! So far just daily driving for work and errands. Slowly easing into longer drives here and there. It’s been dead reliable. I think at this point it’s more of getting my comfort level where it should be rather than testing the Explorer.

My only complaint is the gearing. Still hard to get it off the line in first gear. The TDI makes plenty of torque. The issue boils down to the not so great first gear ratio and the TDI having less rotating mass. I also find myself dancing between third and fourth, and fourth and fifth a lot. Ran some calculations and it looks like 4.56 will get everything back where it should be. (Could also go to a smaller tire but why would I do that?? Ha!)

No time off-road yet. I need to get the gearing situated and fix the parking brake. Once those two are done it’ll be seeing trails soon.

What a bad time to find this thread. My BII has an empty engine bay and is already setup for a M5OD.

I’d seen that you were getting ready to put something new into your BII. Maybe a TDI would be a good fit!

 

[410Fortune]

Tdi in a sport or bii is a “perfect fit” imo
You have shown us the way!!!

 

[Rick]

It’s been working great! So far just daily driving for work and errands. Slowly easing into longer drives here and there. It’s been dead reliable. I think at this point it’s more of getting my comfort level where it should be rather than testing the Explorer.

My only complaint is the gearing. Still hard to get it off the line in first gear. The TDI makes plenty of torque. The issue boils down to the not so great first gear ratio and the TDI having less rotating mass. I also find myself dancing between third and fourth, and fourth and fifth a lot. Ran some calculations and it looks like 4.56 will get everything back where it should be. (Could also go to a smaller tire but why would I do that?? Ha!)

No time off-road yet. I need to get the gearing situated and fix the parking brake. Once those two are done it’ll be seeing trails soon.


I’d seen that you were getting ready to put something new into your BII. Maybe a TDI would be a good fit!

That's good to hear! I am glad it's working well for you.

What gear ratio is in there now?

 

[timtimtimajim]

Tdi in a sport or bii is a “perfect fit” imo
You have shown us the way!!!

Shown the way or possibly helped others make questionable financial decisions!!

That's good to hear! I am glad it's working well for you.

What gear ratio is in there now?

Just the stock 3.73s now. Not bad but could be better. With the 4.56s the plan is to add lockers of some kind.

 

[timtimtimajim]

Ever since I finished this swap the fuel gauge has always read right between 3/4 and full. Couldn’t figure out what was causing it. Nothing changed in the fuel pump, sender, or gauge wiring. I was getting ready to drop the tank this weekend to figure out what was going on.

This morning on my way to work I hit a very large bump in the road. The kind of bump that makes you turn the music down and drive in silence for a little while. I looked down at the gauge cluster to make sure everything was okay and realized that the fuel gauge is now reading correctly! The gauge responds to the typical uphill/downhill level change again. Looks like the float was just stuck for some reason. The big bump dislodged it. Guess I don’t have to drop the tank anymore!

 

[Rick]

Ever since I finished this swap the fuel gauge has always read right between 3/4 and full. Couldn’t figure out what was causing it. Nothing changed in the fuel pump, sender, or gauge wiring. I was getting ready to drop the tank this weekend to figure out what was going on.

This morning on my way to work I hit a very large bump in the road. The kind of bump that makes you turn the music down and drive in silence for a little while. I looked down at the gauge cluster to make sure everything was okay and realized that the fuel gauge is now reading correctly! The gauge responds to the typical uphill/downhill level change again. Looks like the float was just stuck for some reason. The big bump dislodged it. Guess I don’t have to drop the tank anymore!

They do get corrosion on the rods and at the contacts. I'm glad the jolt fixed it.

Last time I had one of those jolts my 4x4 light came on and stayed on in our 2003 Ram. The switch is so difficult to remove that I just unplugged the sensor to keep the light off. LOL

 

[Josh P]

Self healing.

 

[BluIsBlue]

This thread is dangerous for when I’ve got the money and tools and time for this… already been wanting to push more or similar power with better mileage for a while.. if I could get 25mpg combined on my 01 I’d be ecstatic. Been looking at TDI Passats but I don’t want to give up 4WD and all the room for activities in my rig.. hopefully I don’t encounter a point where I need to sell and downgrade because this would be a terrific project for the future when my 01 transitions from a daily driver to a fun truck

 

[timtimtimajim]

Would love to see this swap in a second or second and a half gen! Definitely worth the time and money to keep an Explorer on the road

 

[Rick]

Anything new to report with this build?

 

[timtimtimajim]

A few small things but nothing too exciting…

Been driving it everyday to work (hard to drive the GTI to work when it’s muddy half the time). Got about 3500 miles on the swap now. Upgrading to 4.56s helped a lot with drive-ability. It’s been working great!

Fuel gauge still gets stuck when it’s filled up. Then works again around a half tank when I hit a bump. Seems like the float is getting caught on the return line on the pump. One of these days I’ll either drop the tank or cut an access panel to fix that.

Heater hoses developed a couple small leaks at the clamps. Put some higher quality clamps on and no more leaks.

Ended up adding a vacuum reservoir a month or two ago. The geometry change of the turbo is vacuum controlled. At higher RPM the vacuum pump can’t keep up on its own and would cause a very noticeable stutter. Basically the turbo would switch back and forth between its two profiles very quickly. Reservoir fixed the problem and the geometry change is nice and smooth now.

Still need to add an oil pressure gauge. The factory VW sensor and wire is in place, but the wire was removed from the ECU plug when the harness was built by the last guy. Either need to figure out how to pin it back into the ECU plug so that the Scan Gauge can read the signal or need to add another gauge on the a-pillar. If I go the route of an external gauge, the remote oil filter adapter has an extra port to add another sensor.

Overall it’s been a pretty flawless swap. Fires up with no issues even at 15 below. Drives great and the turbo noises put a smile on my face every day!