Diesel (TDi) conversion discussion & research

[krustyballer16]

My ax15 is holding up well behind my cummins. And the tdi is less power and torque

[ggcnash]

I agree I beleive it will be fine behind the tdi, I was just referring to the comment that they hold up behind a sbc, not the case in my personal experiences.

 

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[krustyballer16]

I agree I beleive it will be fine behind the tdi, I was just referring to the comment that they hold up behind a sbc, not the case in my personal experiences.

 

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Talked it all up and the clutch went out in my cummins mj yesterday... (stock clutch)

[johnj92131]

Krusty, How many miles on the clutch?  Did you go with all new when you did the engine conversion?  I will be interested to know what you find broke.

[krustyballer16]

Krusty, How many miles on the clutch? Did you go with all new when you did the engine conversion? I will be interested to know what you find broke.

17,000 miles. Brand new.

I'll know next week some time

[A-man930]

Bringing it home.  The harness and whatnot come out next.  For those who are curious about the engine I'll be posting up more pictures of it as I go along.  Although I'm forcing myself to finish some other projects before I tear into it too deep.  

 

[johnj92131]

i agree with you both, TDI is the way to go. Good mpg and a good amount of power out of such a little engine. Have either of you found a way to get the VW electronics to talk to the jeep dash?

 

My 86 dash has no electronics, so no issue for me.  The VW ODBII wiring will be mounted in the cab where it can be easily plugged into.  Just like the stock VW. 

[Jaxso32]

Hadn't thought of that, my current plan is to swap in a 96 xj harness and electronics so I can retain the old style dash but have obd2. And from there try and find a way to get the VW electronics to play nice with the jeep dash.

[johnj92131]

Hadn't thought of that, my current plan is to swap in a 96 xj harness and electronics so I can retain the old style dash but have obd2. And from there try and find a way to get the VW electronics to play nice with the jeep dash.

 

WAY too many issues and expensive solutions to go that way.  Just get the TDI  OBDII into the cab, then use a ScanGaugeII for monitoring the TDI engine. Spend your money on an AX-15 transmission with the cable speedometer drive on it.

[Jaxso32]

Already have the ax15 with cable speedo, so no money needed there. I'm just slowly trying to figure out how to make the whole thing work together if possible. Always helps to see what other people think.

[A-man930]

Why the ScanGauge2? Why not just get the factory Jeep senders into the TDi somehow? Might have to get creative with the tach, but the oil, coolant, and volts should be as easy as some thread adapters.

[johnj92131]

Why ScanGauge2?  

 

Because I have used it for years on the Passat and it reads all the VW sensors that the ECU reads, I am simply familiar with it and know it is plug and play with the VW computer.ODBII. 

 

BUT that doesn't mean I will not attempt to get the Jeep gauges working properly.  The Volt Meter and Oil Pressure should be a no brainer. The Jeep boost gauge does not read over 12-15 psi and the scale is near useless.  As for the Tach, I simply have no idea what it will require to make it work with the TDI engine yet.  Just have not thought about it. With all the Jeep TDI conversions out there, I am very sure there is a reasonable solution available.

 

My next step is to get a clutch/pressure plate/flywheel kit.  My AX15 has the internal slave and I am wondering if I should just bite the bullet right now and do an external slave conversion before I run into a future clutch problem like Krusty just did with his 3.3 Cummings. Don't really want to have to pull the trans for a slave cylinder leak.  But converting to the external slave means locating a new bell housing.  Not that hard, just money.
 

[Jaxso32]

Using the older style dash should be easy just wire up the gauges to sensors, if converting to the new style dash is where I would expect there to be some issues. As far as the tach goes I think people tap into the injector wiring and use the injector pulses like ignition pulses to get a tach signal.

[Jaxso32]

I would also recommend the external slave conversion, it's worth it knowing you don't have to drop the trans. If you have a failure

[A-man930]

Knock on wood I've been running around with an internal slave setup since I've owned the truck (almost 8 years) and haven't had anything besides a master cyl. fail.

Granted its only been pushing on a stock pressure plate but still its not quite the ticking time bomb like everyone would like you to think. My $.02:Just keep fresh-ish fluid in there and save your money

[A-man930]

johnj92131 what does your accessory drive look like compared to an ALH? I'm REALLY wanting to leave it all stock but it seems like everybody struggles with it. Especially the ac

[johnj92131]

 I "think" the thread(s) you are refering to concern the Pumpe Duse engines, not the VE pump engines like the AHU/ALH.  I will have to do more reading on TDI Club for older XJ/TDI swaps.  Let me have your email and I will send you some pictures of my 1Z in the Passat.  Also have a partially stripped 1Z on an engine stand, but the accesories like the A/C are gone, so that will not help.

 

EDIT:

I think this thread answers the question about fitting the A/C system with the ALH engine:

 

http://www.4btswaps.com/forum/showthread.php?75161-Jeep-cherokee-TDI

 

Matt Whitbread is doing my conversion, so I don't have the MJ diesel here at home.

[masimmons25]

In the middle of this swap myself, the tdi's need a speed input to run correctly. I am planning on using one of these.

 

http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=126/prd126.htm

 

This should allow for the use of the speed sensor in the transfercase.

 

I'm thinking of mounting the stock vw cluster then adding some additional gauges somewhere for boost, egt, voltage, and oil pressure.

[johnj92131]

In the middle of this swap myself, the tdi's need a speed input to run correctly. I am planning on using one of these.

 

http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=126/prd126.htm

 

This should allow for the use of the speed sensor in the transfercase.

 

I'm thinking of mounting the stock vw cluster then adding some additional gauges somewhere for boost, egt, voltage, and oil pressure.

 

Hi masimmons25,

 

Tell us more about your conversion - which engine are you using and what year is it going into.  Where are you sourcing the TDI to Jeep transmission adapter?  What year Comanche are you converting to TDI Power?

You may want to consider just using the A pillar to mount the egt/boost gauges.  Then use the stock 6 gauge Comanche/Cherokee cluster to pick up the volts, oil pressure, tach, speedo and fuel gauge.  Dakota Digital has a solution for the stock Jeep tach for $85 also. WRONG! Just read post 83 - seems it did not work and there is a simple solution  It is mentioned in this conversion thread:

 

http://www.4btswaps.com/forum/showthread.php?75161-Jeep-cherokee-TDI

[masimmons25]

 

In the middle of this swap myself, the tdi's need a speed input to run correctly. I am planning on using one of these.

 

http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=126/prd126.htm

 

This should allow for the use of the speed sensor in the transfercase.

 

I'm thinking of mounting the stock vw cluster then adding some additional gauges somewhere for boost, egt, voltage, and oil pressure.

 

Hi masimmons25,

 

Tell us more about your conversion - which engine are you using and what year is it going into.  Where are you sourcing the TDI to Jeep transmission adapter?  What year Comanche are you converting to TDI Power?

You may want to consider just using the A pillar to mount the egt/boost gauges.  Then use the stock 6 gauge Comanche/Cherokee cluster to pick up the volts, oil pressure, tach, speedo and fuel gauge.  Dakota Digital has a solution for the stock Jeep tach for $85 also. WRONG! Just read post 83 - seems it did not work and there is a simple solution  It is mentioned in this conversion thread:

 

http://www.4btswaps.com/forum/showthread.php?75161-Jeep-cherokee-TDI

 

I have a 1z from a '96 passat that has been in the family from the factory, already pulled entire drivetrain, accessories, and harness; also have a 2nd 1z complete engine from craigslist ($200 score!).

 

Its going into an '86 4cyl LWB, putting in a 4.10 8.8 to match the front, stealing the ax15 and np242 from my current comanche.

 

As for adapter I'm going with the the coty one (just the adapter not the whole kit) instead of the gastodiesel because it retains a stock starter and is cheaper.

 

The dakota digital adapter i referenced isnt for the tachometer its for vehicle speed, which the tdi ecu needs in order to run smoothly (or so i have read), this adapter will be wired inline between the stock speed sensor in the np242 and the VW wiring harness, it allows for any speed sensor signal to be converted to the right wave form (sine or square) if needed and to calibrate the pulses to what the ecu is expecting at a any given speed.  once this is in place i am going to retain all the other stock vw sensors so the vw ecu is going to think it is still in a passat.  from there i may just install the vw gauge cluster (also picked up one from a vr6 that has the trip computer and can be made to work with the TDI) in the xj dash (97+), and add the extra gauges I want.  If I don't go that route i may buy the Chrysler cluster module that coty sells and utilize the stock 97+ gauges.

 

Hoping to order the Coty adapter later this week (if they're open over the holidays) and have some progress pics up soon.

[A-man930]

So that's three of us. Shweet!

 

I guess I still don't see where evguy's left engine-side mounts attach to the block, and weather or not Jetta ALH accessories will have to be moved at all. His black XJ on the website uses a BEW (pd) engine so I'm guessing the accessory drive is totally different?? johnj92131 are pictures of your 1Z in a Passat gonna be of any use to me?

If only I were a VW guy maybe I'd know some of this, lol.

[johnj92131]

Ordered a LUK clutch, pressure plate and flywheel (new master cylinder also)  from Rock Auto for the TDI Diesel conversion.

 

 Part NumberPart TypePrice EACore EAQuantityTotal1992 JEEP CHEROKEE 4.0L L6LUK01901 (01-901)Clutch Kit$ 157.89$ 0.001$ 157.89LUKLMC206Clutch Master Cylinder$ 21.79$ 0.001$ 21.79LUKLFW193Flywheel$ 45.79$ 0.001$ 45.79Discount $ -11.27ShippingGround$ 30.98Order Total $ 245.18Visa -$ 245.18Balance Due $ 0.00

[A-man930]

Are these upgrade parts or factory? Seems like the TDi crowd likes to smoke clutches.

[johnj92131]

All factory/OEM grade Jeep 4.0 replacement parts.  The LUK 01901 clutch is supposed to be "Heavy Duty", what ever that means. 

 

The 4.0 is rated at 230 lb/ft of torque and stroker versions put out more torque.  The Luk clutches seem to live OK according to on line reports.

 

My TDI engine will be tuned to about the same 230/245 lb/ft of torque, so the Luk clutch should be a reasonable choice for right now. That 230/245 torque rating is the max I can get with the stock turbo.

 

If and when I go to a bigger turbo and more agressive tune, I may well have to replace the LuK clutch with a stronger clutch.  It will be easier/cheaper to replace the clutch in the Comanche than in the Passat.

 

The Passat TDI has a VR6 clutch in it right now with a 300 lb.ft rating and I had to detune the engine to avoid clutch slippage from 315 lb/ft to 285 lb/ft.  Next time I replace the clutch, it will be stronger.  Then I can retune the engine, add fuel back and turn up the boost.  Should be able to hit 350 lb/ft torque at less than 1900 rpms.