TDI Conversion: VW Bus Cold Start Problems

Hello,

I installed an AFN engine from a 1997 Golf 3 into my VW Bus T3 Syncro 16 (the one with the rear engine). Everything works fine, the error memory is clear, the engine starts perfectly when cold, but when starting it when warm, it always takes a few seconds for the engine to run.
The engine was completely installed with all wiring harnesses, the control unit, and all sensors; I'm quite sure I did everything correctly. The only other parts that are different are the air filter, the exhaust muffler, and the speedometer unit. The engine is mounted at a 50-degree angle to the left, with a different oil pan and oil pump.

Other car owners who have modified their vehicles experience the same problem. However, it appears that only engines from Golfs or Seat Toledos (i.e., those with transversely mounted engines) are affected, while those from Passats and Audi A4s do not exhibit this issue. If you temporarily bypass the relay and connect a cold temperature sensor during startup, the engine (allegedly) starts immediately.

What could be the cause of this problem? Do the donor vehicles (Golfs) also have this problem?

Here's the corresponding thread from the VW Bus Forum.
http://www.f1.parsimony.net/forum165/messages/269119.htm

Hello.
Wolfgang.

Hello Wolfgang,

The only thing that comes to mind is to increase the initial amount.
/viewtopic.php?t=439&highlight=adaptionskan%2A+le

Best regards, Rainer.

Hi Wolfgang,

Is the pump also tilted to the left by the same amount?
Could it be that the ESP (Electronic Stability Program) is losing pressure, or that it's not building up the necessary pressure quickly enough when the engine is warm, because it's tilted at such a steep angle?
Is the ESP system in the Audi with a longitudinal engine the same as the one in the Golf with a transverse engine?

If my memory serves me correctly, the longitudinal engine in the Audi Stärker is tilted more than in the VW, so I think the ESP system is also different. The Audi ESP will likely work better in the tilted position.

Just a thought...

Hello,

Thank you for the answers. The pump is also tilted by 50 degrees, but since the original engine also has a VE pump, and they all operate on the same principle, I had previously assumed that it wouldn't cause any problems.

Increasing the initial amount would be a good solution, if it were that simple. Has anyone tried that before? Do I need to increase the numerical value, and in what increments?

I also looked through the archives again. Someone advised Mario from VW to install a new starter motor. Unfortunately, he didn't write whether it helped. It's possible that the original starter motor, which I have, is too slow for the AFN engine.
I probably won't adjust the fuel injection pump like Ulf did.

Hello.
Wolfgang.

I think you can forget about the ESP.
I'm experiencing the same problem with my ATD pump-nozzle engine.
The engine is from a Golf IV manufactured in 2000.
He's currently driving a T3, and I've driven about 10,000 km with it.
The initial set has already been modified once, and some changes have also occurred.
Sometimes the engine starts relatively well, but most of the time I have to crank it for three to four seconds before it starts.
Sometimes I feel like it depends on how long the engine has been off. If I wait 5 seconds after turning off the engine, it starts relatively well, but after 1 minute of standstill, it's the same old problem.
Goodbye.

Hi,

Okay, I was completely wrong. The AFN 97 actually has a tandem pump!! Thanks for the tip about the ATD (~AXR).

The tandem pump only functions correctly at a specific angle of inclination, and therefore it may not deliver the required amount of fluid.

Hello Bertil,

What exactly is a tandem pump? I thought the ESPs in the 1Z and AFN engines only differed in minor details. And the ones in the Passat and Golf are not different at all, and the mechanically driven ESP installed at an angle in the bus isn't fundamentally different either, right?

Hello.
Wolfgang.

Hello Wolfgang,

The tandem pump is a type of pre-feed pump. It ensures a constant inlet pressure for the ESP (especially important for PD). My 1Z didn't have one. The pump is located at the end of the cylinder head (towards the transmission) and is driven by the camshaft. If the pump fails to provide adequate air or cannot maintain the correct pressure, your car will have difficulty starting.
I actually thought only the PDIs had this pump, but last week I saw a Golf 4 (engine code??) with a VP37 that also had this part installed.

Check if you have something like that...

Bertil wrote:

The tandem pump is a type of pre-feed pump. It ensures a constant inlet pressure at the ESP (especially important for PD). My 1Z didn't have one. The pump is located at the end of the cylinder head (towards the transmission) and is driven by the camshaft. If the air supply is insufficient or the pressure is not maintained correctly, your car will start poorly. Actually, I thought only PD engines had this pump, but last week I saw a Golf 4 (MKB??) with a VP37 that also had this part installed.

Hi Bertil.

Have you definitely seen fuel lines from this camshaft pump to the fuel filter or to the VP 37 on the G4 ?

Our ALH-Ibiza also has a camshaft-driven pump, but only for creating a vacuum. Specifically, it replaces the crankshaft-driven vacuum pump found on the AFN (and 1Z?) engines.

Quote:

Now I was on hold. The AFN 97 actually has a tandem pump!!

"Mine definitely doesn't..."

Hello Bertil,

My AFN engine doesn't have anything like that on the cylinder head; it's also from a Golf 3. There was something like that on the Golf 4, but as far as I know, it's the vacuum pump, as Ulf mentioned. Also, it has a different engine code.

Hello.
Wolfgang.

Wolfgang, syncro16 wrote:

Hello Bertil, My AFN engine doesn't have anything like that on the cylinder head; it's also from a Golf 3. There was something like that on the Golf 4, but as far as I know, it's the vacuum pump, as Ulf mentioned. Also, it has a different engine code. Hello. Wolfgang

Hi Wolfgang,

"Tandem" is responsible for both vacuum and fuel supply. You're right about that, but the fuel supply also runs through it.

@ulf

Quote:

Have you definitely seen fuel lines from this camshaft pump to the fuel filter or to the VP 37

I suffer from micro-Alzheimer's, but as far as I can remember, yes.