VW TDI into a 99 XJ

[sweetjeep]

I DO live in an emissions hell hole. I have no idea how that's going to work yet. For now I am choosing to live in a fantasy world where it won't be an issue. I have some questionable contingency plans. The motor is full OBD2.

Otherwise Kastien appears to be hanging out in my brain. Except the part about the tach. That was some fantastic insight I appreciate having!

The power steering is working (more or less), it doesn't "feel right". But.. it does work. It's the VW booster and the Jeep rack.

The vacuum assist for the clutch doesn't appear to be working. The power assist for the brakes is NOT working, or there is something else bunged up. If my crusty memory serves me.. they are devilishly intertwined in some way. Though that could be a different vehicle. Regardless.. it also "feels funny".

The A/C is going to be mildly complicated. I am not sure if the Jeep and the VW use the same type.. so I am not sure if the compressor is compatible. I also know exactly squat about A/C systems. I just know there is magic contained inside and they make my air cool.

The other issue of personal significance will be the cruise. I don't NEED it. But I really do want it to work. This has been solved in the Toyota I know of, so it suggests that I can use similar trickery. The issue to those thinking "dear stupid, just hook it up" is that the TDI is fully computer controlled. There is no throttle plate to adjust. I could go all ghetto and mechanically control the throttle pedal, but that's low rent. I will have to figure out how to convert the Jeep VSS into the VW VSS. I suspect the controls as they sit can be reused. But this is a problem for FUTURE Sweetjeep. Future Sweetjeep hates Today Sweetjeep.

It's also not that big a deal on a 95 or earlier XJ, really... even a 96 wouldn't be too bad, assuming you live in a state that doesn't require plug-in OBD2 for emissions inpection, or use an OBD2 based TDI setup (were there any TDIs earlier than 96? I don't know much about VWs.)

The real complexity comes if you try and integrate a stock 97 and later interior + instrument cluster with the VW setup... wiring becomes somewhat confusing at that point

The 96 and earlier cluster is very easily interfaced to almost anything, the only gauge you'd really have an issue getting to work would be the tach, which on a 91-96 displays 30rpm per Hz of input signal (i.e. 1000rpm = 33.3Hz, 2000rpm = 66.7Hz, etc) which works out to 2 pulses per revolution of the crankshaft. So you could put two diametrically opposed magnets on the harmonic balancer and then use a reed switch, a logic voltage supply (not sure if the tach takes 12v or 5v pulse signal) and a resistor to feed the tach input on the cluster quite easily.

The rest of the gauges are simple - oil pressure and water temp have senders you can screw into any adapter, fuel/speedo are built into the trans and fuel tank so no worries about those.

There are some other issues at hand, that may be cleared up by a lift. The passenger side upper control arm hits the turbo. So that's bad. The driver will probably hit the A/C compressor, that could be bad. That's it for current serious mechinical issues. It looks like I am going to have to slightly redesign the front suspension bits.. but I am hoping that a long arm setup may solve my issues for me. Maybe a custom long arm where the upper brackets are built in to the radius arms. Please forgive me if I am all stupid talking.. my brain is crusty.


I took a bunch of pictures.. they'll be up tomorrow.



Aside from the instruments, you pretty much have to run the starter, feed the computer power during start/run + run, and maybe wire up some stuff for the AC, power steering, and emissions. Aside from that there likely isn't much to do other than trim extra wires and junk out of the factory TDI harness.

 

[kastein]

You might run into issues when the ECU identifies as a VW and tells the computer the VW VIN instead of the Jeep VIN but I think you just have to wire the VW computer up to the right pins on the OBD2 port under the dash and it'll work. If you can get some VW tech at the dealer to burn your Jeep's VIN into the VW ECU somehow (is this even possible? I think it is) I'm pretty sure you will pass with flying colors, as long as the emissions equipment (evap, blah blah blah) is hooked up correctly.

Was the TDI a manual or an auto? If it was a manual it'll simplify things amazingly since it won't be flipping out about the various sensors being missing. I'm not sure how you can get the 99 XJ cluster to talk to the VW electronics just yet but honestly I don't think that's going to fail you. Do you have the VW cluster handy? I bet you could hack it up, and the XJ ECU, and let the XJ ECU run all the gauges except the tach and the VW cluster runs the CEL bulb, then only your tach will really be an issue... and cruise control.

Hooking the fuel system up may be interesting, since the XJ fuel tank and pump are designed for gas you might have to source parts from europe, not sure.

The 99 XJ has a leak detection pump for the evap system that you might have to tear out and replace with VW parts to make the VW system happy, I don't know anything about VW emissions really.

 

[Super mud]

Renix tachs read off the ignition coil. Don't think thats gonna help you on a diesel 99 though lol. Good luck, this OBDII talk scares the shit out of me. Ecu leak detection pump wtf? Also the 99 has a vacuum booster for the clutch? never knew of such a thing but I haven't looked at any newer manual cars either except a 99 wrangler which doesn't have one? With a turbo do you have to draw vacuum before the compressor?

 

[kastein]

... the 99 does not have a vacuum booster for the clutch, unless you are talking about the TDI. What?

EDIT: oh I see it now, TDI related stuff.

 

[sweetjeep]

You might run into issues when the ECU identifies as a VW and tells the computer the VW VIN instead of the Jeep VIN but I think you just have to wire the VW computer up to the right pins on the OBD2 port under the dash and it'll work. If you can get some VW tech at the dealer to burn your Jeep's VIN into the VW ECU somehow (is this even possible? I think it is) I'm pretty sure you will pass with flying colors, as long as the emissions equipment (evap, blah blah blah) is hooked up correctly.

Was the TDI a manual or an auto? If it was a manual it'll simplify things amazingly since it won't be flipping out about the various sensors being missing. I'm not sure how you can get the 99 XJ cluster to talk to the VW electronics just yet but honestly I don't think that's going to fail you. Do you have the VW cluster handy? I bet you could hack it up, and the XJ ECU, and let the XJ ECU run all the gauges except the tach and the VW cluster runs the CEL bulb, then only your tach will really be an issue... and cruise control.

Hooking the fuel system up may be interesting, since the XJ fuel tank and pump are designed for gas you might have to source parts from europe, not sure.

The 99 XJ has a leak detection pump for the evap system that you might have to tear out and replace with VW parts to make the VW system happy, I don't know anything about VW emissions really.

I am still choosing to believe that there is some magic that will happen on the emissions side. I'll worry about that later. Fortunately on the motor I am using emissions equipment is pretty few and low tech.

The TDI was an manual. But that's actually not in regard. I believe there is a separate trans controller (i'm not honestly certain), I am certain it doesn't matter. As to the cluster, there is a procedure to defeat the factory immobilizer system, which has been done. Due to the mechanical pump you can then run the engine on a stand like a carburetor motor. This was also done.

So RIGHT THIS SECOND. The Jeep and the motor don't have any idea they are together and making sweet sweet love. Almost a shame. I have thought about stealing circuits from the VW ecu to make parts of the Jeep dash work as you suggest. Or, slowly learning the system properly. I am still leaning toward hackery.

Like I mentioned, for fuel, the TDI has a mechanical, on motor, pump, so the in tank Jeep pump is only required for the sender. Or possibly as a lift pump and then regulated down. The tank is irrelevant. I'll just need to modify the filler neck as most diesel pumps are larger by a fair margin. I can ignore the evap stuff as diesel doesn't have those issues.

The only real emissions parts the TDI has is an EGR valve and a cat. Off the top of my head, that's it.

... the 99 does not have a vacuum booster for the clutch, unless you are talking about the TDI. What?

EDIT: oh I see it now, TDI related stuff.

Nope.. I think I am being stupid and have my clutch systems mixed up. Which is good. Except that the Jeep's clutch doesn't feel right.

 

[kastein]

What clutch parts and flywheel and stuff were used? If it is jeep flywheel, clutch, pressure plate etc it should Just Work unless the depth within the bellhousing is wrong. Maybe the pilot bearing isn't right? How does it feel wrong?

As long as the jeep master, slave, fork, and a similarly rated pressure plate were used it should react just like a stock clutch pressure wise i think.

 

[sweetjeep]

Renix tachs read off the ignition coil. Don't think thats gonna help you on a diesel 99 though lol. Good luck, this OBDII talk scares the shit out of me. Ecu leak detection pump wtf? Also the 99 has a vacuum booster for the clutch? never knew of such a thing but I haven't looked at any newer manual cars either except a 99 wrangler which doesn't have one? With a turbo do you have to draw vacuum before the compressor?

I think I was being stupid on the clutch thing. Ignore!

Gas vehicles with OBD2 systems have leak detection for the fuel tank and some of the other evap containers for the gas storage. Diesel's don't have that issue. I might need to hack these parts on the Jeep to make it ECU happy. Maybe not.

With the turbo it will not draw vacuum at any point. Perhaps a tiny amount preturbo, but nothing of value. Different diesels generate vacuum in different ways, but they all have a pump of some sort. The motor I am using has a cam mounted vacuum pump to generate vacuum. Some people use the pump off a 7.3 Ford which I don't know how or why. But I know I don't have to. Though I contemplate getting a Hydroboost system for extra power and "simplicity".

 

[sweetjeep]

What clutch parts and flywheel and stuff were used? If it is jeep flywheel, clutch, pressure plate etc it should Just Work unless the depth within the bellhousing is wrong. Maybe the pilot bearing isn't right? How does it feel wrong?

As long as the jeep master, slave, fork, and a similarly rated pressure plate were used it should react just like a stock clutch pressure wise i think.

All Jeep. It does "work" but it feels like there is a high spot in the pressure. Picture it like this.. pressure feels "easy..easy..easy.. stiff..hard.. easy.. easy.. floor".

Again, I have spent the last 250K+ miles driving a Jetta clutch.. maybe I am being weird again. I have another Jeep clutch to compare it to, but I have just not done so yet.

 

[kastein]

A couple of my friends run hydroboost setups on their jeeps and are quite happy with them.

That does sound kinda odd about the clutch, mine is pretty much the same pressure all the way down. Not even sure what would cause that.

 

[Super mud]

So RIGHT THIS SECOND. The Jeep and the motor don't have any idea they are together and making sweet sweet love

that is funny as shit

Don't diesels before a certain year not have emmisions? Maybe it's just trucks but I've heard it more than once. I would still be satisfied if you were only able to drive it in your fantasy land (backyard) when its all done.

 

[sweetjeep]

that is funny as shit

Don't diesels before a certain year not have emmisions? Maybe it's just trucks but I've heard it more than once. I would still be satisfied if you were only able to drive it in your fantasy land (backyard) when its all done.

At least in the People's Republik of Taxachusetts the rules are kinda funny. We, more or less follow the rules in California. So, like I said, I still don't know the answers yet.

 

[sweetjeep]

Pictures.

I hope.

http://s488.photobucket.com/albums/rr250/1sweetjeep/TDI Cherokee/

 

[Lowrange2]

To post the pictures within the thread simply click the link below your image in your album. Click the IMG tag link. It will copy for you and you paste it into the text box when posting.

 

[Lowrange2]

 

[kastein]

At least in the People's Republik of Taxachusetts the rules are kinda funny. We, more or less follow the rules in California. So, like I said, I still don't know the answers yet.

You'll need to plug into the computer for a 99. In a year or two, probably won't - iirc 96s and 97s no longer require plug-in at this point, I know 95s don't.

What bellhousing is that? It almost looks like a Jeep one, but it's too clean... :roflmao:

That engine looks really really small in the engine compartment for a big iron I6. Must be great to have all that space to work.

 

[Lowrange2]

Man, you could store a dead body with all the extra space under the hood!

 

[sweetjeep]

You'll need to plug into the computer for a 99. In a year or two, probably won't - iirc 96s and 97s no longer require plug-in at this point, I know 95s don't.

What bellhousing is that? It almost looks like a Jeep one, but it's too clean... :roflmao:

That engine looks really really small in the engine compartment for a big iron I6. Must be great to have all that space to work.

Yeah. It's ironic. There is a tonnage of space in the front and on the sides. But the turbo location required the frame to be notched and the upper axle control arm currently contacts the actuator for the turbo. So magic will have to occur there. I have pictures, but they induce vertigo if you don't understand what you are looking at.

The pictures you see are with a 2" lift. I don't really care to go higher than 3" for the sake of daily driving. So I think I am going to look in to a long arm 3 link.

On the driverside the A/C compression is close as hell too. But it does clear.

The motor is also needlessly tall. Or more specifically the oil pan is needlessly LOW (causing great grief in the VW community) and I have concerns about it contacting the axle. But I will run the suspension numbers later do determine what, if anything needs to be done.

I contemplate a psuedo dry sump oiling system so I can carry more than 4 quarts. Or leave the pan wet but add a massive tank somewhere in line so I can have a 10 quart total capacity. And possibly shrink the pan at the same time. These are pipe dreams at the moment.

Don't fear the cleanliness of the bellhousing.

I added a couple more pictures to the album.

http://i488.photobucket.com/albums/rr250/1sweetjeep/TDI Cherokee/belowfromrear-1.jpg
http://i488.photobucket.com/albums/rr250/1sweetjeep/TDI Cherokee/motorbelowfront.jpg

 

[Lowrange2]

Just add the IMG tags to the front and end of the URL you posted...

 

[kastein]

That looks really strange with the oil pan at an angle. I suppose it was designed to fit into a FWD vehicle transverse mounted (at least if I remember what those engine compartments look like stock.)

 

[deucestudios]

Cool project.