TheSamba.com :: View topic - ALH TDI fuel injection quantity adjuster power

Fri Mar 30, 2018 10:07 am

I know this is somewhat of an odd question to pose here but I thought that some one who has done a TDI conversion may know the answer to this question. What is the voltage from the engine controller to the fuel quantity adjuster on the ALH TDI injection pump?

The reason I ask this is that I have a complete ALH engine without the engine controller and I would like to test run the engine. I have looked at the wiring pinout and I believe that terminals 1,2,3,4,&5 are used for this function. I also realize I would have to get 12 volts to the fuel shutoff solenoid as well.

I was thinking if I could simulate the signal that would be supplied by the engine controller I could run the engine for a test.

Thanks in advance.

Fri Mar 30, 2018 11:41 am

The voltage to the QA is variable, you can see it in one of the VCDS fields. I think the maximum voltage is 4.4, but I understand that some folks running giant nozzles may tune it as high as 4.9.

I think a typical voltage at key-on is 0.6-0.7. I have no idea what you want to see at idle, and assume that is pretty variable depending on where the IQ is set, what nozzles are installed, fuel temp., etc.

Terminals 5 and 6 on T10f go to N146, which is the QA.

I assume there is a risk of overspeeding the engine if you basically hotwire the IP (assuming you can even get it to start and run).

Have you posted this over in TDI Club?

Edit to add: In case this wasn't clear in my post above, the voltage to the QA changes as fuel quantity changes. That's the whole point. If you set it at a fixed voltage, without any of the other engine management systems operating, it's probably going to be hard to hit the right voltage. Too low, and it won't run. Too high, and the RPMs may exceed engine tolerances.

Fri Mar 30, 2018 12:48 pm

Thank you for your reply HBB.

I have not posted this on the TDI Club yet. I was thinking that someone who has converted their Vanagon to a TDI may have been through this. I don't see why it would not run if the quantity adjuster was getting the proper voltage and the fuel shutoff solenoid were powered. Yes there is a possibility of over speed if too much fuel was delivered.
I am looking at it from the simplest form of engine control and that a diesel will run if it can get fuel. If it started to over speed I would turn off the power and be ready to cover the intake if need be. I will research this further. Thinking I could use a variable potentiometer to adjust voltage to pump and would not need any feedback such as fuel mass airflow, coolant temp, throttle position, fuel quantity feedback etc.

The following text is something I cut and pasted from an information pamphlet from VW.

Fuel quantity control
Function
EDC control unit
The EDC control unit processes the incoming information. From this, it calculates the necessary injection quantity and sends control signals to the quantity adjuster.
Quantity adjuster N146
The quantity adjuster is integrated in the distributor injection pump. The task of the quantity adjuster is to generate the correct injection quantity from the control signals.
The quantity adjuster is a solenoid, a type of electric motor which adjusts the position of the modulating piston via an eccentric shaft and thus regulates the fuel quantity continuously from zero to max. delivery rate.

Fri Mar 30, 2018 1:21 pm

What exactly are you trying to accomplish with this?

These engines will run just fine stripped down (my ALH is running off an AHU ECU, with minimal sensors), but I haven't seen anyone sucessfully set up a standalone engine without swapping the IP out for a purely mechanical unit.

Fri Mar 30, 2018 3:50 pm

Bermoco wrote: I don't see why it would not run if the quantity adjuster was getting the proper voltage and the fuel shutoff solenoid were powered.

The voltage to the QA is adjusted by the ECU depending on several variables, so supplying it with a specific unchanging voltage will result in not enough fuel to make it run, or enough fuel that the engine will run at high rpm with no load on it, if the ECU is not dictating the voltage to the QA I imagine there is no "over rev" protection either as I think that is a function of the ECU. I've never read of anyone doing this, but if anyone has done it it would be someone on TDIclub.

Fri Mar 30, 2018 4:52 pm

What I am trying to accomplish is a test run of the engine that I bought out of a wrecked Jetta. It was already pulled out of the car but they had hacked up the wiring harness and the controller was gone.

Eventually I am going to transplant the engine into my 82 westy. I realize it would be beneficial to buy a controller and fabricate or buy a wiring harness but for now I would just like to see it run.
I will post this on the TDI club but was hoping someone here has done something like this and would say "Yeah that's not a big deal just apply 1 volt dc to pins XX, 12 volts to the fuel shutoff solenoid and crank it over. It should idle".

I will post the results when I figure this out. It may help others who may want to test an engine out of a car.
I am thinking that the electronic injection pump uses the servo motor to vary the fuel rate and at idle it probably has a fixed value.

Fri Mar 30, 2018 5:19 pm

Bermoco wrote: What I am trying to accomplish is a test run of the engine that I bought out of a wrecked Jetta.

That is what I understood from your previous posts, in your situation I'd like to do the same!

Bermoco wrote:
I am thinking that the electronic injection pump uses the servo motor to vary the fuel rate and at idle it probably has a fixed value.

I'm very doubtful that it is a fixed value, when the engine is cold there is more drag on the internals due to cold/thick motor oil so it needs more fuel to maintain idle, 900 RPM, and when its really cold it will idle at 1100 or so for a bit, a hot/warm engine will need less fuel to maintain 900 RPM idle... The injection quantity has to be different for all three of those scenarios, setting up a Potentiometer so you have the ability to vary the voltage could be an option? If you set it up with a fixed voltage to the QA I'd be ready to pull the power to the fuel cut solenoid to prevent over rev.

Fri Mar 30, 2018 5:24 pm

Since you've already bought it, just pull the head and oil pan, and you'll get a good idea about what you're dealing with. I've seen videos of a guy who got an MB drive by wire diesel running in a truck bed with a potentiometer, so it can be done, but I'm not sure it's worth all that effort. My ALH has 200k on it and I got a chance to drive the donor, but I still pulled the head/pan just because. The cylinders looked like they only had 20k on them, and I just lapped the valves and replaced the stem seals. These are one of the best engines VAG ever built.

Fri Mar 30, 2018 5:52 pm

Bermoco wrote: ...for now I would just like to see it run.

It's amazing to me how much time I used to waste on projects like that for similar reasons. At this point in my life I don't really care about the instant gratification of 'just seeing it run' and instead opt for efficiency. What if the engine is a total piece of crap, will you abandon the install altogether or source another ALH? If the former, then I wouldn't waste time making it run outside the vehicle. I'd pull the head and pan and asses the engine condition prior to install and then if it passed muster I'd just complete the install in the vehicle to see it run. If the latter, then I also wouldn't waste time making it run outside the vehicle. I'd pull the head and pan to assess the general condition and if it passed muster then I'd just complete the install in the vehicle to see it run. That whole delayed gratification thing is actually more fun, more exciting, and more efficient.

Fri Mar 30, 2018 6:21 pm

If what you want to accomplish is an assessment of the donor engine, it is probably way easier to (as suggested above) pull the head and pan and do a visual inspection. Plus, if there is something wrong with the engine—particularly if it is out of time—you stand a fair chance of making it worse if you run it.

You could also do a leakdown test. I guess you could also spin it up for a compression test, but, again, if something is wrong, you can make it worse.

Fri Mar 30, 2018 6:26 pm

OP, this video won't help solve your problem, but it does show a TDI running with no electrics (mechanical pump). :shock: :D

I think Zeitgeist 13 and ?Waldo? are exactly right.

HBB, it's amazing you can just drop that knowledge.

love this place!

Fri Mar 30, 2018 7:25 pm

OK. Yes it would be best to pull the head and pan. As far as wasting time to starting the engine outside of the vehicle I don't think that it would take long at all providing I can figure out what the minimum wiring is needed to run the pump. The engine was supposedly rebuilt prior to being wrecked. I did see it in the car before it was parted out, The car was hit pretty hard with both airbags deployed so I doubt it is a bad motor.

If one were to really examine on what is a waste of time that would be restoring/repairing a 35 year old vehicle when you could rent a Westy for a couple of weeks a year to go camping and leave the worries to the rental company, But what fun would that be? Or maybe I should plunk down 50K+ for a done TDI Syncro.

When I bought my Westy it was not running. I towed it to my rural property where I keep my projects. On the way up I decided to add some diesel to the tank as I did not know how much fuel it had. When I opened the fuel cap I noticed that something did not smell right in the tank. Long story short it had about 8 gallons of gasoline contaminated diesel fuel in the tank. Drained it out and flushed the system, primed the pump and started the engine which ran rough for a minute than smoothed out and idled fine. I would have paid a lot more for it if it were in running condition. So that worked out in my favor. The JX motor runs well after replacing the boost controller but it is no TDI. I plan on keeping things the way they are for the summer and fall so I can go camping in it. Probably will do the swap over the winter. For now I will acquire the needed parts.

Again this is more of a hobby. I will check the timing, turn it over with a wrench to make sure nothing is broken. Hopefully I will figure out the needed wiring, use extra diesel bell housing and starter and run it.

Thanks for all the comments and feel free to post more. I have fairly thick skin and enjoy the Samba.

Fri Mar 30, 2018 7:36 pm

One more thing: if the engine is a dud I have a 2002 Jetta TDI that I have had since 2006. I bought it when it had 60K on it. It has 278K on it now and still drives and runs great. I could use it as a donor but I am amazed at its durabillity and want to run it till the wheels fall off of it. I would rather rebuild the 98 motor.
Will not have internet access for a day or so. Thanks

Fri Mar 30, 2018 9:12 pm

Bermoco wrote: The JX motor runs well after replacing the boost controller but it is no TDI. I plan on keeping things the way they are for the summer and fall so I can go camping in it. Probably will do the swap over the winter. For now I will acquire the needed parts.

With it currently a JX, you might reconsider the ALH and instead opt for a Mk3 TDI (AHU, 1Z, AFN). The Mk3 TDI engines will allow you to use all of your JX mounting bits for an almost bolt-on swap. You'll get the same performance and fuel economy as an ALH. Even the JX K14 turbo is a good match and would make for a very simple install. For perspective, I did a 1.6TD to AHU mTDI swap on one of my vans in three days (a long weekend) and could have done it in a day except I needed to rework the custom exhaust due to the taller block. ALH will be a lot more custom work for mounting and/or custom pan.

Fri Mar 30, 2018 9:44 pm

Yep. The ALH is a LOT of work to put in these vans. Using all the factory diesel bits is way way way easier.

Sat Mar 31, 2018 4:13 am

I recall a thread where someone worked out a simplified way to run these engines. It was not just to start it. I recall they were in the Netherlands. It was probably on the TDI website in the conversion forum. Going to take some digging to find.