My TDI BEW PD WVO Conversion Approach
 

Note: Skip to Process (below) if you just want to hear my intentions on the conversion.

The vehicle in question is a 2005 VW TDI BEW PD Jetta Wagon.

Abstract: I've been running on WVO for years with older 1.6 TD's and 1.6 NA motors. I'm very familiar with the processes involved and have installed, repaired, upgraded all aspects of WVO vehicle systems. With several breakdowns over the years for any number of reasons, some of which had nothing to do with WVO I've become quite familiar and comfortable with working on cars. I always filter my oil and ensure there's no water in it. I always ensure an adequately high temperature before switching over and purge the system before shutting down. At this point there's nothing I have seen or worked on. I'm not a certified mechanic but rather mechanically inclined. To give you some insight in this respect: My latest project involved dropping a 1.6 TD into a Suzuki Sidekick in which I hand crafted an adapter plate to connect the bell housing on the Suzuki transmission and lined up the input shaft to the crank shaft on the VW diesel motor. I had no working template and drew out everything by hand. It works. With that said I can confidently say I do have 'some' skill I suppose. The technicality involved with respect to this conversion won't be that difficult for me, however, it seems there's a growing divide with respect to the TDI community and the ability for this motor to run on WVO. As such I've done an extraordinary amount of research on this specific topic to ensure the best possible results. Providing there is an interest I may post the process here.

Devils Advocate: There's no need to give me feedback on how well the WVO needs to be filtered and the importance of temperature. I'm well aware of these issues. I'm also aware of the viscosity differences between WVO and diesel, polymerization and the concerns with the EGR in addition to the substantially higher pressures these injectors have compared to the older VW's. And yes, I've heard the horror stories of those that have tried and failed. Nevertheless, if your point merits enough concern that you need to share in lieu of an oversight you feel I may not have appreciated enough or over looked – then please do.

Assumptions: My process outlined below assumes I've done the following: I've already installed the second tank (it'll be a dual tank system), tapped into the coolant to which I'll connect to a heat exchange located inside the tank, install a lift pump between 8 – 11PSI, have both supply and return solenoids for the diesel and WVO fuels. It also assumes I'm filtering down to 5 microns and will have both an in-tank temp gauge as well as one that's closer to the pump on motor.

Process:
1) Disable/delete the EGR. It's legal in Canada. I understand that race pipes are available for some TDI's. I also understand I'll need to tune theCPU in order to remove the permanent CEL as a result. At it's most basic level my understanding is that you can simply unplug it to disable it. I thought about taking it a step further by installing a race pipe and keep (what I believe is a solenoid on mine?) intact (still wired) yet outside in the air intake hence it would still be connected to the CPU and hence, in theory, shouldn't produce a CEL. I need to do more research but disabling the EGR is critical.

2) Install an EGT sensor. This is critical for two reasons.

- WVO systems aside it's going to communicate how healthy of a combustion I'm receiving
- It's going to provide a benchmark with respect to where I should be seeing my WVO combusting.

3) Install a Resistance Wire for the Fuel Temp. Based on my research this is what makes running WVO that much more plausible on these engines. Installing a resistance wire will fool the CPU into thinking the fuel is colder and hence adjust the timing accordingly. I've seen some guys simply place in a 2k ohm resistor. I'm taking it a step further:

I'm installing 1k ohm resistance in addition to a 0 – 10k variable resistance potentiometer. This will be connected to a switch that I can turn on/off at will giving me the ability to completely remove the added resistance if need be. By monitoring the EGT's I'll be able to adjust the resistance using the variable resistance potentiometer to the exact sweet spot which calls for a complete combustion of the WVO.
Note: This all assumes the BEW PD has a fuel temp wire (I did see the harness on the return line but will need to do more research in this area).

4) Install Switches and Gauges. To give you a better perspective here's a list of the various gauges and switches I'll be installing in the car:

- Fuel Temp (Resistor) on/on switch – This will have to be on on both settings as noted above. One being the default temp wire resistance and the second with the modification I discussed above to include both the 1k ohm resistance and 0 - 10k ohm adjustable resistance.

- Fuel pump (TDI) on/off – my understanding is that there is a lift pump within the BEW PD engine and hence it doesn't make sense to have it running if I'm switching to veg.

- Fuel pump (WVO) on/off – My understanding is that an 8 – 11 PSI inline pump should be adequate for this engine.

- Fuel solenoid (Supply) on/on switch – The nature of one of the solenoids I have requires on/on -hence one will be diesel and the second will be WVO. There are secondary valves on this system to allow for a return, however, I don't like how they both work at the same time – this could potentially allow for WVO into this diesel tank.

- Fuel solenoid (Return) on/off – I like to keep this switch separate from the supply solenoid as I always purge diesel for a few minutes back into the veg tank.

- Fuel heater (canister) on/off – I have various heaters that I'll be installing, this one specific to the oil filter which I'll be installing just outside the tank. Another system I'll be implementing (from an older system that worked excellently) is wiring up an inverter and plugging in a magnetic oil heater (300 watts) that is located on a large, aluminum heat exchanger inside the WVO tank.

- Fuel temp sensor (tank) – I like to know the temperature of the WVO in the secondary tank. This sensor will be located at the coldest possible spot.

- Fuel temp sensor (inline at pump) – A means of monitoring the temperature of the WVO right before it goes the the pump.

- EGT gauge – As previously explained this will be critical for monitoring the health of the combustion process

- Variable Resistance Potentiometer – This 0 to 10k ohm adjustable resistance (in conjunction with the inline 1k resistance) will allow me to manually adjust how much (or how little) resistance should be applied to the WVO system based on the EGT readings.

If anything, I'm looking for feedback with respect to the feasibility and practicality of my proposed approach. What am I doing wrong in your opinion? What did I miss or neglect to mention? What would you do differently?

I used to run WVO in my ALH TDI, well filtered and de-watered too. The fatty acids are an issue and build up on the heads and valves. When the head came off due to a timing belt event, that is when I found out. I have been instructed due to the mechanically more technical aspect of the PD injectors and nozzles, using WVO is not a good idea for some of the same reasons. It is your vehicle, and if you wish to have short service intervals on your PD motor, then by all means go ahead and run WVO. You don't mention of your treating your WVO for fatty acid reduction, are you going to be doing that to your WVO before you run it?

I've been mixing my WVO with baking soda to neutralize/minimize the fatty acids. Been doing this for 2.5 years and 50k miles on my 06 Jetta. I'll be doing the timing belt and water pump maintenance in 30k miles and will report my findings. Thank you for the heads-up!

Did your engine have any sort of EGR system and if so was it disabled?

And that could very well be the case.

That's a really good point. I haven't installed the system yet so anything is possible. It wasn't my intention to. If there's a fatty acid build-up on the valves and otherwise in the head my guess would be it's a result of any number of the following:

1. polymerization as a result of contact with cooler metals
2. Incomplete combustion
3. Incorrect timing - too much WVO
4. Insufficient pre-heating of veg oil

Unlike like other systems (that I've read about) that run a greater risk of polymerization by failing to disable the ERG - by doing so any fatty acid build-up is less likely on the valves (or atleast the valve stems) and everything else from air intake side of the head. Atleast that's my logic. This means my WVO will get injected, pumped out the exhaust valves and that's it. Although, while writing this, you made think of how polymerization and/or fatty acid build-up could have potential implications with the turbo as it's essentially powered by exhaust fumes.

Incomplete combustion (point 2) I believe also relates to point number 3 (incorrect timing and too much WVO) which I could see resulting in fatty acid build-up. My intention on avoiding this was to monitor the health of the combustion through the use of an EGT gauge in addition to adjusting the resistance as noted above. This will also result in adjusting the timing and inadvertently amount of WVO presented to the injectors. This is to suggest that if I only call for the correct amount of WVO to be burned then there will be less likelihood of fatty acid build-up.

Irrespective of my points perhaps fatty acid build-up is inevitable in spite of the precautions and processes I'm intending to implement. Perhaps I should be considering taking additional measures with preparing my WVO with respect to removing fatty acids. Assuming I don't - what other possible precautions could one take above and beyond my suggestions? Thank you for your insight.

That's be great. Any information on these newer TDI WVO systems seems to be obscure at best.

Welcome to the club. Good plan, and a very nice summary.

The last VW I ran on WVO was an ‘06. I did not go nearly as far as you - no fuel temp resistor, no EGR delete and thorough filtering, but only for dirt and water. It worked just fine.

A couple thoughts on your system. Are you not using engine heat (antifreeze) to warm your tank, filter and lines? I’ve found that efficient, reliable and “free”. You could also eliminate some of your switches by using a relay to toggle between the fuel pumps. IIRC, I had two switches, one switched the solenoids and fuel pumps, and the other just for purging. Actually, there was a third, to turn on the “Vegitherm” in-line fuel heater.

Otherwise, it sounds like you are doing everything right. Please keep us posted. And if you ever find yourself in Connecticut and needing fuel, stop by.

Very cool bud. Thanks for the response and offer. I might just take you up on that if I take a road trip that way.

How many kms did you get on your system and was it a BEW PD?

Yes, I thought I mentioned that in the initial summary at some point. Tapping into the anti-freeze lines seems quite logical as it's essentially free heat. I'm going to create a heat exchange that I'll place in my tank specific to this purposes. For the sake of clarifying my heating implementation in it's totality: This would be in conjunction with (likely) 3 (or possibly 4) other electronic heating systems:

1. 300 watt oil pan heater attached to an aluminum heat exhchanger that I acquired from one of those thermoelectric generator coolers/heaters - located in the veg tank and to help dissipate the heat within the tank and hence oil.
2. A 12 volt silicone oil filter heater which will located immediately outside the tank and connected to my 5 micron oil filter - right before it goes to my self-priming fuel pump.
3. An inline 12 volt heating (system of sorts) at the lowest point of the fuel line between the veg tank and the engine. This is because heat rises and the logic is to provide heat at what is likely the coldest spot.
4. Some sort of coolant/fuel heat exchanger where the coolant immediately leaves the engine (hence it's the hottest possible) and to which the WVO fuel is just about to go into the engine.

For some they may see this as overkill. However, it gets cold here in Canada. Without (pt.1) the car would take forever to heat up. (pt.3) comes from personal experience as I have seem fuel lines get extremely cold. I'm still trying to determine the best approach for this (pt.3). For anyone that's played with filtration and WVO, heat always helps to get things moving hence (pt.2). All in all potentially upwards of 400-450 additional watts on the existed vehicle system until it gets up to temp to which I'll disable/adjust/turn off things accordingly as not to burn out the voltage regulator on the alternator.

Both the supply/return fuel lines would be wrapped around some sort of insulation between the WVO tank leading to the engine bay - with the coolant lines around them for whatever the heat from the supply/return coolant lines is worth.

I'm familiar with the inline-heating systems with coolant/veg lines and even worked on one that had failed. Although they seem superior in some ways for generating heat I just find them to be too risky. To elaborate: Coolant (with a greater PSI - I'm guessing 20 for that vehicle?) is more likely to leak into your fuel system and get to your engine before you even know what's going on if the inline hose system fails.

Yes, good call. Believe it or not that's actually something I've been pondering. In some instances with respect to my switch layout it would make sense to have one switch for two independent functions instead of two for individual functions. Although I will say it's nice to hear the solenoids click to ensure they're connected/working (for periodic maintenance/testing when the car is off) and this wouldn't be possible with a pump running in the background.

On a side-note with another WVO vehicle I had ('91 Jetta): I previously installed a second alternator used exclusively with a second deep cycle battery that I place in the back seat that could be turned on/off with a switch. This had no connection with the main battery/system. It allowed me utilize the block heater for up to 4 hours (1200 watt battery to 300 block heater element) without any concern for using/draining the starting/main battery. This way when I'm out for a week in the woods I can come back to the car at -30 degrees and start it after an hour or so without issue.

I had a 2006 Jetta. The engine was a PD; I don’t recall if that was a BEW. I think all US Jettas had the same engine in 2006 so I’m sure someone on here knows. I bought the car with 75K (miles) and converted it to WVO right away. I think it had 250K when I sold it, and it was running fine. I never had any reason to open up the engine so I can’t say how it looked inside.

My cars always used the “hose in hose” coolant heated fuel lines. I understand your concern, and I was afraid of that too, but never had any problems at all. It does make a LOT of heat, and the oil comes out nice and hot. I also had a coolant line wrapped around the fuel filter.

Where in Canada are you? My car did take a while to warm up on those cold winter nights, but by the time the engine was up to temp, the oil was warm enough to switch to WVO. Winters are mostly 20 degrees F or so, but we see a few nights well below 0. And I drove up to Vermont where we would see -20F or colder.

One interesting thing I did find in very cold weather concerned purging. If I purged right before shutting down, the car would be a bit harder starting in the morning. If I purged a few miles before I got home, it would start normally. So apparently even with a full purge, there was still a bit of vegetable oil left somewhere in the lines. I wouldn’t have thought so, because the car moves quite a bit of fuel through the pump and back to the tank.

Did you really need the second alternator for ‘91? Couldn’t you just charge the battery from the main alternator? Sounds like you enjoy a challenge... That’s not a bad thing, of course.

Northern Ontario



I agree with your logic on this. I always purge for extended periods of time.




I suppose not in some respects. However, it really would have bogged down and burnt out the main alternator in no time I'm sure. I used the accessory battery for a lot of various things. A second alternator gave me peace of mind.




Sounds like you were one of the lucky ones according to some of the horror stories that I'm confident you've heard. In some respects this makes me feel a hell of a lot better knowing I'm literally over-killing my precautions as a means of ensuring the best possible chances of success. Thank you for your feedback.

For those interested here's a wiring diagram a created with how I should wire things up with respect to the fuel temperature resistance aspect of this project. I needed to create one to confirm my wiring layout with some chaps online that know a lot more about electricity then I do. Needless to say everyone agreed it's the correct set-up.

With the toggle switch in the left position the fuel temperature wire is in it's default and otherwise within its original setup. With the switch in the right position (as shown) resistance is added (to be used when running on WVO). The potentiometer and switch would be located in the dashboard area. (Based on this wiring) turning the potentiometer right would increase resistance to the fuel temp sensor wire. The consensus I've read online when others, having simply implemented a resistor, are mostly using a 2k ohm resistor. My logic is to have 1k ohm static resistance (for lack of a better term) with the option of adjusting additional resistance using the potentiometer (which ranges anywhere from 0 - 10k ohms) based on the EGT readings and otherwise as needed.

Please let me know what you think.


https://i.ibb.co/4407YBg/temp-sensor-wiring-diagram.jpg

Sort of a silly question, but why do you need the resistor and the pot? Wouldn’t the potentiometer alone do the same thing?

This configuration allows for:

1) with the switch in one position, 0 additional resistance in series with whatever the operating resistance of the fuel temp sensor is

2) with the switch in the other position, between 1K and 11K additional resistance in series with the fuel temp sensor

If a range from 1K - 11K is what the OP is after then all good... but given that 0K is allowed (first switch position) then the reason for the 1K resistor in series with the 10K pot is a reasonable question, since it will limit the lower end of the pot to half the target 2K.

Better question, why do you need the switch or the resistor? If you simply add the potentiometer inline, you can set it to add anywhere from zero to 10k ohms of resistance between the temperature sensor and the ecu.

Two points to consider:

1. The pot should be a linear taper. An ordinary volume control pot will have a logarithmic taper and the resistance will change more rapidly as the angle of rotation increases.

2. The switch contacts will operate opposite to the handle position. This means your description of the selection is reversed. That is, as shown, it is in the default position without the extra resistance.



Sort of a silly question, but why do you need the resistor and the pot? Wouldn’t the potentiometer alone do the same thing?

Yes, it would, but the fixed resistor assures a minimum value of resistance. Without it, the pot could be turned to zero ohms and so would not do anything.


HTH

True, although the switch does provide a easy way to go between "stock" and "a value I have determined that works".

Another thing that occurs to me is the entire thing assumes the OEM fuel temperature sensor decreases its resistance as temperature goes up... if this is not the case adding resistance in series will trick the ECU in the wrong direction.

Presumably those that recommend a 2K additional resistor have confirmed this... but ya never know on the interwebs?! :)

Quote:

Originally Posted by philngrayce (Post 5460202) Sort of a silly question, but why do you need the resistor and the pot? Wouldn’t the potentiometer alone do the same thing?

Not silly at all. In fact a very smart observation. My logic is detailed below.



That is correct.

Quote:

Originally Posted by Vince Waldon (Post 5460207) If a range from 1K - 11K is what the OP is after then all good... but given that 0K is allowed (first switch position) then the reason for the 1K resistor in series with the 10K pot is a reasonable question, since it will limit the lower end of the pot to half the target 2K.

No one knows the target hence my idea to install a pot. Maybe it is 2k ohms. Maybe 5k ohms is ideal. More details on this below.

Quote:

Originally Posted by P2B (Post 5460217) Better question, why do you need the switch or the resistor? If you simply add the potentiometer inline, you can set it to add anywhere from zero to 10k ohms of resistance between the temperature sensor and the ecu.

Ahh. Good point! However, it makes sense to have a fixed resistor in place (which I'll explain in a second) and because I'll be running on diesel at times I'd like to have the ability to resort to the original settings. As for the switch, it's easier to flick a switch once you've determined your ideal resistance as opposed to constantly adjusting a dial each time to the perfect spot every single time you switch over the WVO.

Now: Why the purpose of a fixed resistor and a pot?

(For those that don't know pot refers to the variable resistor potentiometer - I learned the hard way)

Technically it can be done exclusively with a pot and no fixed resistance. My understanding and suggestions from those that know a lot more about circuitry is that we would want the pot to be ideally or nominally at the half point of resistance. By having as much (minimum) fixed resistance in place while still having a full range of resistance through a pot (that I would like to cover) I will have finer control or tuning with respect to the amount of resistance. This will provide for greater accuracy. In a perfect world were I knew the exact amount of resistance needed there would be no need for a pot. Once I have a better idea (when the system is running) I can, in theory, reduce the size of my pot allowing for even finer control.

Why 1k ohms? Why not 2k ohms?

I thought about this a lot. 1K ohms comes from a very popular thread where this inline fuel temp wire epidemic started: http://forums.tdiclub.com/showthread.php?t=152468

In that specific example he's using 2.2k ohms. Around 2k seems to be the consensus with anyone having any degree of success with this mod. Hence my logic dictated that starting off with a fixed resistance of 1k ohm's is probably going to be a safe minimum. The 10k pot gives me a variable range from 1k to 11k ohm's as previously suggested. I've heard about one guy on that thread that installed a 15k ohm resistor. That seemed a little excessive to me.

The original thread on this topic is 10+ years old and hence the information on this topic is scarce at best.

The amount of resistance will determine how cold the CPU see's your engine as being. As a result it will advance the timing with greater resistance. Does maximum advance timing of the engine for a BEW PD occur at 6k ohms? 7K ohms? This is to suggest that there is a point where the engine can only advance the timing so much hence the amount of resistance you apply above and beyond what is required would be redundant. These are questions in which Google, let alone any forum (no disrespect here by any means) I have a hard time see answering.

With all that said my approach with a 1k ohm resistor and 10k pot is an educated guess at best. These seem to be the safest numbers and approach based on my research thus far. And while I would love to have more information and specifics on the exact numbers needed I think I'll have better luck bumping into a unicorn. In some respects I'm not concerned as the EGT will tell me everything I need to know (with respect to how much resistance) when everything is running.

Quote:

Originally Posted by Alchemist (Post 5460218) The pot should be a linear taper...

Yes, that was the intent. Good advice.

Quote:

Originally Posted by Alchemist (Post 5460218) The switch contacts will operate opposite to the handle position. This means your description of the selection is reversed.

Ha! That's funny. I'm no electric expert. When I drew it I figured if it was 'up' the right terminal would be active. Good to know. Oddly enough the chaps on another specialty circuitry website never spotted that one. That's for pointing that out.