1.9 Conversion Woes

[Rifleguy308]

My dad installed a 1.9 TDI out of a 2000 vw new beetle into his 1981 Rabbit truck.  The pump was missing so he used a spare pump off of a 1.6 naturally aspirated VW.  The truck will run, start and idle flawlessly.  It has no power to go however.  Barely runs 20 mph.  He things he has too much timing in it.  I believe the pump is incompatible based on the pressures.  I don't know where to get this information and would welcome any suggestions on what to do. I just blew up the motor in my rabbit 4 door and would love to borrow his truck for my 100 mile a day commute while my rabbit is laid up.  Thanks in advance.

[theman53]

The 1.6 pump will not deliver enough fuel especially at the right time to sufficiently power a TDI

[vanbcguy]

Yup, you need a different pump.

[burn_your_money]

Crank the fuel screw in so that you have a really high idle (1500-2000) and you can do 55. Maybe.

You do need a new pump, or swap the camplate, and head and rotor into the 1.6 pump housing and you'll get by for a bit. It's a lot harder than it sounds, and a lot harder to do correctly but if you don't mind trashing a pump or two (possibly instantly) you can give it a shot.

[ToddA1]

Tyler, what makes the above swap difficult?

I was planning on swapping the mentioned parts (TDI intermals) into a 1.6 pump.

-Todd

[vanbcguy]

The TDI cam plate and head are only part of the puzzle. The TDI needs a lot more dynamic advance than the 1.6. The TDI needs more control collar movement than the 1.6 governor lever is set up for. The TDI pump doesn't have donor parts for either of those things since it controls them electronically.

[ToddA1]

Gotcha.... If that's what he was referring to, it makes sense.

My plan was to swap the parts into a 1.6 pump and run it on a AAZ.

-Todd

[vanbcguy]

Yeah you could do that I suppose, and end up with a 10mm IDI pump. That'd be a screamer! If you do have an AAZ pump around it has the best cam plate to use.

There is also a shim between the pump head plunger and the cam plate btw. It is what sets the pump stroke properly for the combination of parts you have. If it's not right you can have issues. The problems mentioned above - the pump head is really fragile. If you break the plunger it's garbage. So for instance putting everything together with that shim out of place or having one that's too thick can trash the head instantly.

[ToddA1]

I grabbed the camplate, rollers, shim, rotor and head from a junk AHU pump from the JY.  These parts have to be better than what came in the 1.6 pump.  I've had several of these pumps apart, so I'm not too worried. A little petroleum jelly glues it all together for assembly.

I don't have a AAZ TD pump... Just a normal U.S. ALDA pump.  I've heard people say to just swap the ports and it works the same. I guess I'll find out....

I'm guessing the AAZ camplate is steeper? 

-Todd

[vanbcguy]

Yup, AAZ has the most lift and still has an IDI shape to its ramp.

Sounds like you will be all good.