Vanagon AAZ throttle response

[wjdzl]

Hey guys, have just bought a Vanagon with AAZ swapped in, and the throttle response / usable range seems kind of weird.  Basically the first 1/3-1/2 travel of the gas pedal seems to do nothing, even when under no load (clutch in).

It actually feels really lerthargic even at full throttle until you hit what feels like a kickdown switch and then it  wakes up.

This is my first diesel vanagon, but something just doesn't feel right.  Is there anything I can check / tweak?  We are driving it home across a few states so I would welcome any driveability fixes we could try.

Many thanks, really excited to be a part of the club!

[theman53]

It is injection pump related. Either the lever is a few splines off or the main fuel screw is out too far would be my guesses.

[wjdzl]

It is injection pump related. Either the lever is a few splines off or the main fuel screw is out too far would be my guesses.

The indexing was my suspicion too.  Is there an way to tell by looking at it?  I have some pictures but unfortunately on cell phone, I could email if you want to PM me your address?

I found another thread that talks about indexing by the pump looked different.  Mine seems to have 3 spring segments on the "throttle shaft"?

Really appreciate it.

[libbydiesel]

It is injection pump related. Either the lever is a few splines off or the main fuel screw is out too far would be my guesses.

The indexing was my suspicion too.  Is there an way to tell by looking at it?  I have some pictures but unfortunately on cell phone, I could email if you want to PM me your address?

I found another thread that talks about indexing by the pump looked different.  Mine seems to have 3 spring segments on the "throttle shaft"?

Have someone else press the accelerator pedal while you are watching the pump lever and shaft.  Does the shaft immediately start turning when the pedal starts being depressed?  With the stock AAZ return spring setup, the accelerator cable is attached to a lever that is spring loaded to rotate the shaft.  If the resistance of the shaft is increased for some reason (e.g. dirt) then the spring loaded lever could start moving for a little while before the shaft starts to turn. 

Do you have an EGT gauge?  What are the EGTs on an extended grade?  Do you have a tach?  What rpm are you idling at?

Really appreciate it.

[wjdzl]

So on gas, the lever rotates (because it has to) but the middle spring doesn't appear to start moving for awhile, which "feels" like it represents my dead area.

Here are the pictures:

[tdihuntdawg]

 check your go pedal cable adjustment . I have the same setup and there is little room for exsess slack. And I had to move the ball in to get more travel . The adjustment is in the ft. Under the pedal. Also a spare cable is handy to carry or you will learn what driving by "wire" is all about.  GLEANERDAWG

[wjdzl]

It is injection pump related. Either the lever is a few splines off or the main fuel screw is out too far would be my guesses.

The indexing was my suspicion too.  Is there an way to tell by looking at it?  I have some pictures but unfortunately on cell phone, I could email if you want to PM me your address?

I found another thread that talks about indexing by the pump looked different.  Mine seems to have 3 spring segments on the "throttle shaft"?

Have someone else press the accelerator pedal while you are watching the pump lever and shaft.  Does the shaft immediately start turning when the pedal starts being depressed?  With the stock AAZ return spring setup, the accelerator cable is attached to a lever that is spring loaded to rotate the shaft.  If the resistance of the shaft is increased for some reason (e.g. dirt) then the spring loaded lever could start moving for a little while before the shaft starts to turn. 

Do you have an EGT gauge?  What are the EGTs on an extended grade?  Do you have a tach?  What rpm are you idling at?

Really appreciate it.

Hey Libby,

So I'm not sure I have it straight. In my mind, the cable pulls the arm which is connected to the shaft and has a spring " around it" to return the arm / provide resistance for the pedal.

Why I don't grok is my three spring setup where one is doing what I describe (top one) the middle one seems to be a second stage that starts moving around 35-50% of arm movement and I have no idea what the bottom segment is doing...

Unfortunately no EGT or tach at this point, both are on the list after we get home.  Idle seems a little high, but I don't know these motors that well yet.

[wjdzl]

So, possibly a stupid question...  How do I reindex the arm or is it not something I should attempt?

Alternatively it sounds like dirt could cause this also, do you guys suggest trying to lubricate it?

[libbydiesel]

It looks like the top lever is welded to the intermediate lever.  In that case, the top spring is doing nothing at all except applying pressure to the two welded parts.  The bottom two springs are doing all the returning of the lever.  I would check the timing, get an EGT gauge on it, adjust the fueling.  I'm not sure what to suggest on the road.  Is it smoking at full pedal?

[wjdzl]

No smoke as far as I can tell, even at night with headlights following.

I might try to take a video of the throttle action.

[libbydiesel]

If there is no visible smoke at all at full pedal, I would turn up the max fuel some.  Don't go nuts without an EGT gauge, though.