TDI swap in Jeep Wrangler TJ

Jayden

Jayden

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Apr 20, 2021
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Granbury
Hello I am brand new to this forum!! My name is Jayden and I’m 17, my first vehicle is a 1999 tj and we’ve had some problems with the factory 4.0, so instead of pulling it out and putting it in a 4th time or 5th time I have decided to put a TDI in it from a 2006 VW Jetta.(engine code BRM) I was wondering if anyone has done a swap like this and could give me some tips/tricks/diagrams/websites ETC.

This is my daily so I will be doing motor work on the tdi(freshening it up) and then pulling out the 4.0 and initialize the swap. It’s going to butt up against the automatic 3 speed that came with the jeep. It has been rebuilt and might have 5,000 miles on it by now. My goal is to have it done by summer of 2021 and drive it to school at the beginning of my senior year. With this jeep I go by built not bought so all the work has been done by me and my dad so I’d like to keep it that way with the exception of tuning and adapter plates.

D171DDA4-4121-4D83-96F3-5570E07A5C96.jpeg


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Hey Jayden I was going to say I’m currently getting through my swap, but Wildman already posted it! You are going with a different engine code than I am( BRM as opposed to ALH) which is actually supported a little better through a company called Cotybuilt which makes parts for Jeep swaps with your engine I believe.

don’t be afraid to fabricate stuff yourself though if you went with them you’d be paying a huge amount at the cost of being bolt in for the most part. Give yourself about 150 to 200 hours of actual time working on it , and at least a 20% buffer on budget

while my build thread won’t exactly be applicable to your swap, feel free to contact me if you have any questions!

Good luck!
Brett
 
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brett313 said:
Hey Jayden I was going to say I’m currently getting through my swap, but Wildman already posted it! You are going with a different engine code than I am( BRM as opposed to ALH) which is actually supported a little better through a company called Cotybuilt which makes parts for Jeep swaps with your engine I believe.

don’t be afraid to fabricate stuff yourself though if you went with them you’d be paying a huge amount at the cost of being bolt in for the most part. Give yourself about 150 to 200 hours of actual time working on it , and at least a 20% buffer on budget

while my build thread won’t exactly be applicable to your swap, feel free to contact me if you have any questions!

Good luck!
Brett
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Thank you sir, would you happen to have any diagrams for the jeep tj 4.0 and what you did to the wires and jeep things that you didn’t need for the tdi
 
Jayden said:
Thank you sir, would you happen to have any diagrams for the jeep tj 4.0 and what you did to the wires and jeep things that you didn’t need for the tdi
Click to expand...
You’ve actually touched on the one part of the swap I was saving for last. I’m sorting out tdi wiring and accessory systems first then get to the Jeep wiring after. I used the Haynes manual to help me cut down the TDi wiring harness, but it wasn’t strictly necessary.

I’d recommend trying to make your VW engine into a standalone system, then basically just run whatever is leftover in the Jeep that you actually need, basically just lights and instrument cluster.

For this reason also, I’d recommend moving to a manual transmission for basic simplicity. I think you will need a shift controller computer for the Jeep auto transmission but I know next to nothing about it. Maybe one of the gurus can chime in if there are aftermarket TCUs available.

I will work on a microcontroller interface between the Jeep gauges and the VW CAN bus, but not before I get my swap completed
 
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brett313 said:
You’ve actually touched on the one part of the swap I was saving for last. I’m sorting out tdi wiring and accessory systems first then get to the Jeep wiring after. I used the Haynes manual to help me cut down the TDi wiring harness, but it wasn’t strictly necessary.

I’d recommend trying to make your VW engine into a standalone system, then basically just run whatever is leftover in the Jeep that you actually need, basically just lights and instrument cluster.

For this reason also, I’d recommend moving to a manual transmission for basic simplicity. I think you will need a shift controller computer for the Jeep auto transmission but I know next to nothing about it. Maybe one of the gurus can chime in if there are aftermarket TCUs available.

I will work on a microcontroller interface between the Jeep gauges and the VW CAN bus, but not before I get my swap completed
Click to expand...
On the tj they had the 3 speed that was shifted hydraulically and then in 2003/2004 they changed to the 4 speed that was electrically controlled *I BELIEVE* so I think I should be fine on tranny stuff. You said you will work on a micro controller interface between the jeep gauges and the vw CAN bus? What is a CAN bus amd why can’t you splice into the (ie) oil pressure sending unit so it can be read in the keep cluster?
 
I was able to get into the motor a tad and the cam shaft looks good, there is 0 sludge and metal and the things the cam lobes slide on look good they aren’t worn out like I’ve seen/ heard of. But once you get to the intake and exhaust side it’s a little dirty on the inside of the intake pretty bad... should I clean it or let it be?

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Jayden said:
On the tj they had the 3 speed that was shifted hydraulically and then in 2003/2004 they changed to the 4 speed that was electrically controlled *I BELIEVE* so I think I should be fine on tranny stuff. You said you will work on a micro controller interface between the jeep gauges and the vw CAN bus? What is a CAN bus amd why can’t you splice into the (ie) oil pressure sending unit so it can be read in the keep cluster?
Click to expand...

well in that case you should be okay so long as you can check with the engine/transmission adapter company you are planning to buy from and can verify it will all fit up.

A good test might be to unplug all wires going from your ECU to the transmission (if there is any) and seeing if it will properly shift and lock the torque converter. again, I have no idea how the TJ Autos are running I’m just giving general advice that may or may not be applicable.

You should also run some gearing calculations with your transmission, and axle ratio, and tire size to verify that you will be in an acceptable rpm range at highways speeds. You may want to regear so don’t forget to check.

the CAN bus on VW’s and many other modern cars is a communication system between sensors, the central ECU and many other parts, any data that exists from a sensor on the engine and is sent to the ECU will be able to be pulled off and read by the microcontroller (with a fast update rate too).

the microcontroller is a better solution that reading gauges individually because it is highly unlikely that the sensors from the VW can drive the Jeep gauges directly. It is very likely that there will be a pulse timing, voltage, or other conversion factor that will need to be applied to work properly.

If you use the VW CAN communication, you can read all these sensors from only two wires with the microcontroller then, command the Jeep gauges to move with respect to what is read, the tachometer, coolant temperature, manifold pressure, and oil pressure and temperature are all available via CAN. The only special case is speedometer which exists on the Jeep transfer case, and the fuel level, which is clearly in the fuel tank.

The following image is a screen cap from Cotybuilt website, apparently, if you have the EDC16 ECU it actually needs a speed input signal from the Jeep too, so that’s a bit more complication for you. If you have an EDC15 ECU like mine on the ALH you don’t need to know vehicle speed.

A132B4BA-C6B1-46ED-B52C-076DEC6F4C6A.jpeg


overall it’s just a lot cleaner method that trying to get each VW sensor wired up and driving their respective gauge on the dash.

On the ALH engine with rotary injection pump, you definitely don’t need all this stuff, it’s just nice to have working gauges. Check to see which Bosch ECU you have and get back to me. I might be able to help if you have the EDC16, but it would be challenging The alternative is buy a working ECU harness from cotybuilt for 1500
 
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brett313 said:
well in that case you should be okay so long as you can check with the engine/transmission adapter company you are planning to buy from and can verify it will all fit up.

A good test might be to unplug all wires going from your ECU to the transmission (if there is any) and seeing if it will properly shift and lock the torque converter. again, I have no idea how the TJ Autos are running I’m just giving general advice that may or may not be applicable.

You should also run some gearing calculations with your transmission, and axle ratio, and tire size to verify that you will be in an acceptable rpm range at highways speeds. You may want to regear so don’t forget to check.

the CAN bus on VW’s and many other modern cars is a communication system between sensors, the central ECU and many other parts, any data that exists from a sensor on the engine and is sent to the ECU will be able to be pulled off and read by the microcontroller (with a fast update rate too).

the microcontroller is a better solution that reading gauges individually because it is highly unlikely that the sensors from the VW can drive the Jeep gauges directly. It is very likely that there will be a pulse timing, voltage, or other conversion factor that will need to be applied to work properly.

If you use the VW CAN communication, you can read all these sensors from only two wires with the microcontroller then, command the Jeep gauges to move with respect to what is read, the tachometer, coolant temperature, manifold pressure, and oil pressure and temperature are all available via CAN. The only special case is speedometer which exists on the Jeep transfer case, and the fuel level, which is clearly in the fuel tank.

The following image is a screen cap from Cotybuilt website, apparently, if you have the EDC16 ECU it actually needs a speed input signal from the Jeep too, so that’s a bit more complication for you. If you have an EDC15 ECU like mine on the ALH you don’t need to know vehicle speed.

View attachment 247866

overall it’s just a lot cleaner method that trying to get each VW sensor wired up and driving their respective gauge on the dash.

On the ALH engine with rotary injection pump, you definitely don’t need all this stuff, it’s just nice to have working gauges. Check to see which Bosch ECU you have and get back to me. I might be able to help if you have the EDC16, but it would be challenging The alternative is buy a working ECU harness from cotybuilt for 1500
Click to expand...
In my jeep im running 35's with a 3:73 gear ratio, i will get a picture to you of my ecu later on in the day today.
 
brett313 said:
well in that case you should be okay so long as you can check with the engine/transmission adapter company you are planning to buy from and can verify it will all fit up.

A good test might be to unplug all wires going from your ECU to the transmission (if there is any) and seeing if it will properly shift and lock the torque converter. again, I have no idea how the TJ Autos are running I’m just giving general advice that may or may not be applicable.

You should also run some gearing calculations with your transmission, and axle ratio, and tire size to verify that you will be in an acceptable rpm range at highways speeds. You may want to regear so don’t forget to check.

the CAN bus on VW’s and many other modern cars is a communication system between sensors, the central ECU and many other parts, any data that exists from a sensor on the engine and is sent to the ECU will be able to be pulled off and read by the microcontroller (with a fast update rate too).

the microcontroller is a better solution that reading gauges individually because it is highly unlikely that the sensors from the VW can drive the Jeep gauges directly. It is very likely that there will be a pulse timing, voltage, or other conversion factor that will need to be applied to work properly.

If you use the VW CAN communication, you can read all these sensors from only two wires with the microcontroller then, command the Jeep gauges to move with respect to what is read, the tachometer, coolant temperature, manifold pressure, and oil pressure and temperature are all available via CAN. The only special case is speedometer which exists on the Jeep transfer case, and the fuel level, which is clearly in the fuel tank.

The following image is a screen cap from Cotybuilt website, apparently, if you have the EDC16 ECU it actually needs a speed input signal from the Jeep too, so that’s a bit more complication for you. If you have an EDC15 ECU like mine on the ALH you don’t need to know vehicle speed.

View attachment 247866

overall it’s just a lot cleaner method that trying to get each VW sensor wired up and driving their respective gauge on the dash.

On the ALH engine with rotary injection pump, you definitely don’t need all this stuff, it’s just nice to have working gauges. Check to see which Bosch ECU you have and get back to me. I might be able to help if you have the EDC16, but it would be challenging The alternative is buy a working ECU harness from cotybuilt for 1500
Click to expand...

5F1D246E-7B4F-4DBA-8683-07D584BF2B18.jpeg
 
Jayden said:
View attachment 248579
Click to expand...
Yup that’s the EDC16 ecu. So you have two extra things to sort out with the electronics.
1. You will need to find a way to send the speed signal to the ecu
2. You will need to find a way to lock your torque converter which from my research is electrically activated with a solenoid.

you could use this calculator also to check to see if you are okay with the rpm range you will be putting your motor at when you are driving at highway speed

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator
 
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brett313 said:
Yup that’s the EDC16 ecu. So you have two extra things to sort out with the electronics.
1. You will need to find a way to send the speed signal to the ecu
2. You will need to find a way to lock your torque converter which from my research is electrically activated with a solenoid.

you could use this calculator also to check to see if you are okay with the rpm range you will be putting your motor at when you are driving at highway speed

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator
Click to expand...
I don’t really understand the locking of the torque converter, when we had the motor and trans rebuilt there was the speed and 4wd sensors on the transfer case and one sensor that I could only think that it’s a tac sensor at the top of the bell housing. I went to the website and if I did it correctly it said 70mph at 2500RPM (the current motor in the jeep is 70mph at 3400RPM) but again not sure if it’s 100% correct
 
I’m getting ready to do the a tdi swap on my 02 Jeep tj. I’m trying to find some info on wiring. What can be deleted from the Jeep wire harness. I’m planning on using fast forward wiring harness to connect everything to the tdi
 
808jeeper said:
I’m getting ready to do the a tdi swap on my 02 Jeep tj. I’m trying to find some info on wiring. What can be deleted from the Jeep wire harness. I’m planning on using fast forward wiring harness to connect everything to the tdi
Click to expand...
I’ve heard good things about FFA but I’ve emailed them and done their google form and I’m supposed to get an email but all they keep saying is “check your spam folder” so they are kinda holding me back at the moment and I don’t know of any other company that makes stand alone wire harnesses
 
Jayden said:
I’ve heard good things about FFA but I’ve emailed them and done their google form and I’m supposed to get an email but all they keep saying is “check your spam folder” so they are kinda holding me back at the moment and I don’t know of any other company that makes stand alone wire harnesses
Click to expand...
Does Coty built not make one? I thought they did but it’s double the price
 
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Look on the Facebook group TDI swapped trucks. there is a vendor on the site that sells a stand alone harness that everyone is happy with.
 
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