thanks guys...

@ Stacy ---  I checked the vacuum large hose to the plenum, clams are
tight, no visible crack... there's one way vacuum valve (yellow color) on
it... could it be bad?

@ Bruce --- it behaves consistently for the last 3 months... and yes the
symptom is very similar to a cold engine but doesn't go away when it's warm.

@ Zoran --- I did have the timing checked by my mechanic recently with his
fancy timing light (I didn't have one as good as his, so I let him do it)

@ Stuart --- Goood idea ! ! ! - I will borrow the one from my other van to
see there's any improvement...

to all for more infos...

- the engine was rebuilt by a well known mechanic in SoCal. 5K miles ago...
so I ruled out compression - I was running OK after the rebuild but not
excellent and the mechanic said it's normal since it needs a good break in
- and he's too far away from me (1K miles) so I can't get back to him... I
am in Oregon, he's in Southern California... :-(

- I put in a set of Marco Mansi HiPerfo injectors last year - so I ruled
out bad injectors.

- Also I think it could be a worn throttle body... hmmmm...  $280.00 to
test, I may end up getting one if there's no cure...

- I use this link to adjust/test the AFM -
https://www.thesamba.com/vw/forum/viewtopic.php?t=356377 - the AFM (3 of
them) are all correct to the specs...

thank you all... I will report back my findings...

On Mon, Apr 19, 2021 at 11:07 AM Zoran Mladen <zmaninco@yahoo.com> wrote:

> Check timing...did not see that on your list...and while doing so...ensure
> the distributor is working correctly.  When you rev the engine the timing
> should advance about 30 degrees.
>
> Z
>
> On Monday, April 19, 2021, 12:04:20 PM MDT, Dan N <dn92610@gmail.com>
> wrote:
>
>
> hi all,
>
> my 89 tintop Syncro has this weird issue that I try to find how to fix...
>
> From standing still in 1st gear the van (empty van) is very unresponsive,
> something like it has no power at all, slow moving. If I rev it up to
> between 2K rpm to 3K rpm, the power comes up and it moves, like normal as
> it should - otherwise once it's running it works fine all gears, no lack of
> power.
> If I stop, put it in 1st gear then it did the same again, engine cold or
> warm it doesn't matter.
>
> I did the followings:
> - check vacuum - no leak
> - check TPS - it clicks well as it should
> - new spark plugs NGK BP6ET
> - new dist. cap and rotor
> - new fuel pressure regulator
> - new fuel filter
> - new Temp2 sensor at the thermostat housing.
> - new Oxygen sensor at the cat
> - air filter is very clean
> - put in a spare AFM - and another one - no change
> - spark plugs color is grayish, not white and not brown.
>
> The one thing I guess is the valves are not opening/closing correctly (on
> one o2 2 cylinders), not checking this yet.
>
> I am lost... Please help if you have any idea.
>
> thanks in advance
>
>
> thanks in advance
>