2003 Jeep TJ TDI HPA

Im currently in the process of fitting a BEW TDI into my Jeep TJ and I figured seeing as information on the conversion is very scarce that starting a topic on it might bring more information out of the woodwork. I am actually very close to completion of the project although most of the wiring is still to be done.

Ill start by saying that I ended up using the HPA motorsport kit. I do get alot of satisfaction from doing everything myself but honestly making adapters to the precision required if way beyond my current ability. Their parts are not cheap and in my case not even a total bolt on but they are high quality and their customer support is excellent.

There are alot of opportunities to fab up parts for a project like this and I have done just that for pretty well everything other than the adapter and truss member which I got from HPA. Because I wanted to keep it as factory looking as possible I did try to adapt as much jeep stuff as possible too.

Any advice on adding photos to this post would be great. I have a photobucket account but dont know how to use it. There are still some things in the process of being done like piping the intercooler and mounting the ecu's but all the fab work has been done and im just waiting for a nice day to paint and for my silicone coupler to arrive.

Anyways feel free to ask whatever questions you have and ill try to answer as best I can. If anybody else has done something similar please let me know if you see anything I can improve or tips about something that can up with your swap. Ill try to add ifo about all the things ive done with this one as I go along. Cheers

Id love to hear about the fit and finish of the adapter. Ive been working on my own adapter for too long and Id like see more of it other than the product photography on the HPA site.

Here is the jeep before I started to rip into it. The jeep was in excellent condition when I bought it. If I hadnt drove it for a week and realized how terrible the 4.0 in on fuel I might have even felt guilty about tearing apart a perfectly function jeep. My garage space is really limited which is another reason for buying the conversion parts...all in all I think that the HPA kit is worth the expense.



Engine/Trans out



Here is the 2 piece adapter bolted to the block (steel plate then aluminum plate) Not sure if all the kits require it. There is a crankshaft spacer that the jeep flywheel bolts to aswell. The passat starter is also bolted up but what you cant see is the adpater that allows it to line up to the ring gear. All the parts are shown on HPA's website so I dont see the need to post them all but the fit is very precise and would be extremely difficult to scratch build or even replicate.

Here is the motor in the jeep with the truss member supplied by HPA. I thought about making my own mounts but again decided to just go with the bolt/weld in solution. Im glad I did because it is a really well thought out part that still allows for timing belt changes and access to everything. Im keeping the jeep filter housing as well as the jeep radiator for the stock look. HPA has used the VW cooling stuff with success but to me the jeep stuff is already in place so there is no need to re-invent the wheel.


This is where I am at now. Some of the things that are harder to see in this picture and the fuel filter bracket which is made to tuck the filter close to the brake booster. I also made a bracket to fit the VW vacuum/pressure solenoids next the the battery. Also behind the battery is where the VW ECU and Jeep powertrain module are being mounted. the bracket is made up but isnt pictured. For the cooling fan I got a electric one that comes from a 2005 TJ. They bolt right up the the TJ rad and also provide the right mounting tabs for the power steering pump and cooling overflow bottle. I also made the bracket to mount the intercooler which will require a small hood vent but its really the cheapest/simplest solution compared to a water/air setup or front mounting one. There just inst alot of space ahead of the rad and really no place to run the piping. The top mount also reduces the piping lengths which is always a plus. It might look alittle crooked in the picture but it does mount up staright when its bolted into place.The Maf sensor will be between the airbox and turbo inlet but im waiting on the silicone coupler to finish that up as well as for the charge pipes which as just 2 90 degree bends welded together.

Other things that require attention is modifying the jeep fuel tank setup and installing the VW lift pump. I did all of this with a mix of parts from the jeep and VW. An inline pump is also an option but I decided to put the pump back in the tank and use all the factory harnesses.

The wiring is another matter entirely and I haven't sorted it all out yet but I think that it will be a combination of Jeep and VW. The jeep instrument cluster is fed information from the powertrain module via can-bus so I need to keep it mostly intact in order to have gauges. My plan is to have the jeep wiring and ecu hooked up normally but run the VW Ecu piggybacked to it running the engine. I have most of the pinout's and diagrams needed but havent motivated myself to tackle it yet. Also its nice to have everything in place to see where the harness needs to be routed...etc so it is kinda the last task.

I hope the pictures help alittle for anybody who might be thinking about this. Hopefully the results will be worth the effort when I get it out on the road!

Thanks for the pictures! It looks like you made some great progress already!

I love the R34 also.

Thanks for the compliments. The car in the background is an R33 GTR not an R34. The R34 does not become legal to drive until 2014.

Made alittle more progress on the swap today. The couplers arrived in the mail so I was able to connect everything together. The hotpipe was really easy to make, it was simply 2 90 degree bends welded together. I was able to keep the jeep airbox also which makes for a cleaner look. All that is left is the wiring now which im hoping will be pretty straightforward. The ecu bracket is also bolted up and now holds both the jep powertrain module and the TDI ecu. I picked up a hood scoop that is around the right size and height. Havent decided if im going to try to colour match it or paint it black but it should grab enough air for the intercooler without looking ridiculous.

Great work. Good luck with the wiring, please document it well. This swap may have to be in my future.

If you're still looking for a lift pump, check Reddok's Liberty build. I think he said a Cummins lift pump/sender unit dropped right into his jeep tank, and worked with the right pressures and everything.

mcneil said:

If you're still looking for a lift pump, check Reddok's Liberty build. I think he said a Cummins lift pump/sender unit dropped right into his jeep tank, and worked with the right pressures and everything.

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I looked over that before I decided what to do but because I already had a TDI pump/sending unit and a Jeep Pump/sending unit I decided to just use the pump from the TDI and install it in the jeep sending unit. This allowed me to keep all the jeep fuel gauge and harnesses intact. because the jeep uses a regulator on the top of the tank and a returnless system in removed the pressure regulator and just made an adapter to hook the fuel line up. For the return line I used an extisting jeep fuel line (emissions line) and converted the rollover vent/check valve into my return to the tank. Ill post some pics tonight for anyone interested. The Cummins pump would work too but because I already had the parts I wanted to use them.

If you converted the rollover vent into a return how will the tank vent when you fill it? My Cummins sender didn't have a provision for a vent and without one, I had trouble filling the tank - it would keep shutting off the pump. I had to drill a hole in the top of the tank and add a vent back in. Good work so far. Looking forward to seeing another TDI Jeep out there.

Reddok said:

If you converted the rollover vent into a return how will the tank vent when you fill it? My Cummins sender didn't have a provision for a vent and without one, I had trouble filling the tank - it would keep shutting off the pump. I had to drill a hole in the top of the tank and add a vent back in. Good work so far. Looking forward to seeing another TDI Jeep out there.

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My understanding is that the rollover valve prevents gas from leaking into the evap/emissions system if you end up upside down. There are two of them on the top of the tank...The one on the left prevents it from going back to the engine side of the emissions system and the one on the right is for the evap/carcoal canister. I took the valve portion out of the left side one as its the one closest to the stock fuel lines. The one on the other side goes directly to the evap canister in the fenderwell which I left hooked up but I didnt remove it as its not in the way of anything. The tank vent is the hose that comes up beside the fill hose and should allow air to escape. Im not sure why you had fill problems but either way if you got it figured out then it doesnt matter now. Here is a picture of the TJ tank...perhaps the Liberty tank is not the same.


Here is a picture of the BEW pump installed in the jeep sending unit. I kept the diesel pickup filter and only had to cut the bottom of the jeep sending unit abit to get it to fit right. The sending unit has little feet which hold up the pickup filter perfectly but allow it to be very close to the bottom of the tank.


Here is the pump inside the unit. The filter clips on the the bottom of the pump very tightly so it holds the pump down into the sending unit very well. The power and ground wires just splice into the ones that used to go to the jeep pump and after the jeep pressure regulator is removed the pump outlet hose just comes out of the top of the tank.



I guess I didnt take a picture of the tank all together and ready to bolt back up but it looks almost like an OEM tank. I re-used the factory fuel line clips so the pressure line and return line just clip back up to the factory fuel lines on the rail.

All this was in attempt to keep everything as stockish as I could. It also keeps the costs down all these parts are already made to fit and work. The Harness and relays are already well thought out by Chrysler so there is no need to re-invent the wheel. The fuel sending unit on the jeep communicates the signal throught the powertrain module which then communicates the information through canbus to the instrument cluster.

pix of skyline plz!!!!!!!!!!!!!!

Dsmart said:

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NV3550, correct?

I've wanted to do a similar build, but want to use the NSG370. I'm also debating to wait until they (HPA) have some swap parts available for the JK, and NSG370 in a JK I think would be a good stepping stone to a nice Wrangler.

In the long run, it'd be nice if Jeep came out with a diesel Wrangler sometime soon, but my guess is that they would start out at some unbelievably high asking price, so swapping a JK would still be a good deal in that case... Time will tell, when they put out a diesel Wrangler...

Love the build!

The Liberty tank/sender is totally different:



Liberty sender on the right, Cummins sender on the left. I didn't really have the option of modifying the Liberty sender as the 35psi+ pressure regulator was built in to it and it wouldn't have worked with the 5psi of the Cummins lift pump.

On my Cummins/Wrangler swap, I used the jeep pump in tank, and put a regulator downstream, with a second return line to tank, to get the desired pressure. The pump was putting out about 60psi if I remember correctly, and I bumped it down to 5psi with Edelbrock regulator.

So you were able to reuse the gasoline pump for diesel with no issues? I always wondered if that was possible.

This is how I did the motor mount on the front of the block. I had to do some custom A/C lines and my oil heat exchanger is relocated due to my starter location, but it would probably work with the exchanger in the stock location too.

You are correct my transmission in the nv3550. I think the 6 speed would be cool to have behind the TDI also but honestly would probably just find myself skipping gears because the extra torque really doesnt need them. Interestingly enough the nv3550 has a lower 5th gear than the nsg370's 6th 0.78 vs 0.84 which coupled with the right tire size should allow slightly better mileage on the highway (purely speculation!)

I was talking with HPA afew days ago and apparently they are working on the wiring for a JK so I wouldnt be suprised if they have a kit available soon.

Jeep does make a diesel wrangler called the J8 but its only available oversea's and is built for military use. Same idea as swapping in the 2.8crd so really it shouldnt be that hard of a conversion...expensive...but the extra power would be nice in the bigger jeep.

As far as the fuel system goes there are many solutions to the problem. Keeping the stock HP fuel pump and regulating downstream would work just fine but the thought of heating up the fuel by pressuring it to 60psi then heating it up again at the regulator to get the 5psi just to send it back to the tank seems like under certain conditions (hot weather and empty tank) could lead to problems. Volkswagen felt the need to add a fairly large fuel cooler for the TDI even with just the low pressure pump! Anyways time will tell.

Keep the info coming fella's, Im sure as you all know there isnt a wealth of knowledge available online for these so the more that comes out the better.

For the guy asking for the skyline pics here ya go...its off topic but because I have to carefully work around it when im in the garage I consider it part of the project!

The six speed works well behind the TDI. I can only fit 265/75 tires under the Liberty and I sit around 2000RPM at 100kph. The NV3550 would really lug in 5th if I had it in my setup. Of course a set of 4.10s instead of 3.73s in the diff would fix that too.

Not sure I would use the NSG370 if I had to do it again. The manufacturers maximum gearbox torque is only something like 270ft/lbs and it's not the smoothest shifting transmission.

My plan is to run a stage 1.5 tune and stock tires so im hoping lugging wont be an issue.

Reddok said:

So you were able to reuse the gasoline pump for diesel with no issues? I always wondered if that was possible.

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Yup, no issues so far. Pump out the gasoline with a jumper at the fuel solenoid, then fill with diesel, maybe pump out again till you're sure diesel comes out, and hook it up to the engine... Basically what I did.

If it does go bad, I'll maybe put a new oem jeep fuel pump in and see how long it lasts as a new pump since the old pump has nearly 200k miles on it. If the new pump fails after a short period of time running on diesel, then I'll maybe go back to the drawing board for it though.

Dsmart said:

You are correct my transmission in the nv3550. I think the 6 speed would be cool to have behind the TDI also but honestly would probably just find myself skipping gears because the extra torque really doesnt need them. Interestingly enough the nv3550 has a lower 5th gear than the nsg370's 6th 0.78 vs 0.84 which coupled with the right tire size should allow slightly better mileage on the highway (purely speculation!)

I was talking with HPA afew days ago and apparently they are working on the wiring for a JK so I wouldnt be suprised if they have a kit available soon.

Jeep does make a diesel wrangler called the J8 but its only available oversea's and is built for military use. Same idea as swapping in the 2.8crd so really it shouldnt be that hard of a conversion...expensive...but the extra power would be nice in the bigger jeep.

As far as the fuel system goes there are many solutions to the problem. Keeping the stock HP fuel pump and regulating downstream would work just fine but the thought of heating up the fuel by pressuring it to 60psi then heating it up again at the regulator to get the 5psi just to send it back to the tank seems like under certain conditions (hot weather and empty tank) could lead to problems. Volkswagen felt the need to add a fairly large fuel cooler for the TDI even with just the low pressure pump! Anyways time will tell.

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Can't wait to hear that they have a kit for the JK. Will have to evaluate my options for transmissions in the future.

Fuel system for my Cummins is definitely different than the TDI, so yeah, doing the in-tank change is probably smarter. Can't imagine that the fuel gets heated up a ton, but who knows.

Dsmart said:

You are correct my transmission in the nv3550. I think the 6 speed would be cool to have behind the TDI also but honestly would probably just find myself skipping gears because the extra torque really doesnt need them. Interestingly enough the nv3550 has a lower 5th gear than the nsg370's 6th 0.78 vs 0.84 which coupled with the right tire size should allow slightly better mileage on the highway (purely speculation!)

I was talking with HPA afew days ago and apparently they are working on the wiring for a JK so I wouldnt be suprised if they have a kit available soon.

Jeep does make a diesel wrangler called the J8 but its only available oversea's and is built for military use. Same idea as swapping in the 2.8crd so really it shouldnt be that hard of a conversion...expensive...but the extra power would be nice in the bigger jeep.

As far as the fuel system goes there are many solutions to the problem. Keeping the stock HP fuel pump and regulating downstream would work just fine but the thought of heating up the fuel by pressuring it to 60psi then heating it up again at the regulator to get the 5psi just to send it back to the tank seems like under certain conditions (hot weather and empty tank) could lead to problems. Volkswagen felt the need to add a fairly large fuel cooler for the TDI even with just the low pressure pump! Anyways time will tell.

Keep the info coming fella's, Im sure as you all know there isnt a wealth of knowledge available online for these so the more that comes out the better.

For the guy asking for the skyline pics here ya go...its off topic but because I have to carefully work around it when im in the garage I consider it part of the project!

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grrrrrrrrrrrrrrrr, so sexy!!!!! my friend had an s14 kouki converted 240sx with an rb25 motor, crazy fast, then one night we got tboned, true story, he paid a butt load of money for the car, and only had it for a couple months

Had some time today and tackled the exhaust. It was a cheap and easy project. All that is needed is a 24" piece of 2.5 OD exhaust tubing that is flared on one end to 2.5" ID. You will need to cut the factory exhaust flange off of the muffler inlet. The 24" piece then slips over the muffler inlet and gets welded or clamped and slips over the HPA downpipe and gets clamped (I welded the muffler inlet end and clamped the downpipe end). This allows you to use the factory jeep muffler and allows you to complete the exhaust system for a grand total of $10. Im not the sure if the factory jeep exhaust is the same for the 2.5 vs 4.0...mine was a 4.0.

I am tackling the project as well and am wondering if you have any incite on the wiring and how that should go. Almost have the fuel hooked up so wiring is the next beast.

The jeep is now up and running. I moved from province to province so it basically drove out of the garage and went on a 7 hour test drive loaded to the max. There are afew things to report. The mileage was actually better than I expected, the jeep went around 800kms on the first tank which for most of it was hauling 300-400lbs of gear. The intake air temps seem to be quite high even with my hood vent and shroud around the intercooler. They can get upward of high 70's which im not to happy about. Im going to add a fan on the bottom of the intercooler to drawn air through and hopefully it helps. The stock jeep cooling system works great and ive had no issues with it. My jeep has the NV3550 tranny and stock sized wheels and I find that the rpms are alittle low. The rear end gear ratio may need to be changed from the 4.10. right now the rpms are around 2000 @110kms. A previous posted mentioned this would be an issue and it certainly seems to be. The voltage regulator in inside the Jeep PCM and for whatever reason it failed on me so I just bought an external regulator to sort that out. All that is left it to add the jeep coolant/oil pressure sensors and figure out a trigger signal for the jeep tach. The tach gets its signal from the crankshaft position sensor which is on the bellhousing and wired in but apparently needs a trigger signal from the cam sensor which is no longer there. I tried using the VW coolant gauge sensor but it operates differently from the jeep one. the sensor has 4 wires...2 for the engine ecm and 2 for the gauge. It would have been nice if it worked but no such luck.

Anyways I think the swap works out really well, the engine seems to be a good match for the vehicle and once all the little details are sorted out it doesn't feel like you are driving a Frankenstein. Ill post some final pictures when I get a chance. If anybody has questions about the swap feel free to ask here or PM

I ended up taking the jeep cam gear apart and removing the sensor wheel. With a little grinding, it slipped over the tdi cam bolt washer. I tack welded it in place and mounted the jeep cam sensor to the timing cover. With the Dakota sgi5 my tach works normally now. Sure beats the momentary push button I was using before.

Edit. My jeep has 3.07 gears in the rear end so I will need either 3.73 or 4.10

Reddok said:

I ended up taking the jeep cam gear apart and removing the sensor wheel. With a little grinding, it slipped over the tdi cam bolt washer. I tack welded it in place and mounted the jeep cam sensor to the timing cover. With the Dakota sgi5 my tach works normally now. Sure beats the momentary push button I was using before.

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If I still had the engine I would do just that...very clever solution. Ill have to come up with something else unless I can find some used parts. Perhaps the VW cam sensor would provide a suitable signal also?

Dsmart said:

Edit. My jeep has 3.07 gears in the rear end so I will need either 3.73 or 4.10

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I was gonna say, having 4.10 gears shouldn't give you that speed. Having 3.07 makes sense.

I would try the 3.73. I have 4.10 in my jeep (with diesel swap), and wish my RPMs were a little lower.

Dsmart said:

Perhaps the VW cam sensor would provide a suitable signal also?

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No cam sensor on the ALH. I tried scoping the Jeep to figure out what the ECU was looking for, but without a function generator and a digital playback scope, I couldn't get anywhere. There is a specific pattern in the cam sensor wheel that the ECU needs to see in order to determine which cylinder is firing. I could trigger it by tapping the cam sensor wire to ground a couple of times and then the tach would work just off the crank sensor, but I got tired of doing that every time I started it. You can buy a replacement cam gear for the Jeep and take it apart. (I got lucky and found a liberty in the u-pick).

Mine is a BEW, I may be wrong but I think it does have a cam sensor. As to whether or not it is suitable as a trigger is another story.