A report on the poly-insert side motor mounts

[fspGTD]

I have a popping noise when I accel/decel sometimes that is my top priority.  I was hoping to solve it with the new mounts, but there was no help.  I am wondering CV joints possibly?  Doesn't seem to worsen when turning tight radius, the noise commonly happens just coasting forward, in fact.  None of the CV boots are torn, but both halfshafts are cheap high mileage rebuilds, partly why I am suspecting them.

I also found one spot where the exhaust system downpipe could come into contact with a pressure hardline on the the power steering pump.  There is only about 1 finger thickness of clearance, could hit under heavy accel.  I'm not confident that's really what my popping problem is though, since it happens with conditions other than hard accel.

I think I found this popping noise I was baffled on earlier (as noted above...)  it indeed looks like one of the spring-clamps from the downpipe flex joints was hitting under acceleration, on one of the power steering rack hardlines, and this was obvious as there was a divot in the poor hardline from where it was getting hit.  (This was easy to spot with the head and the turbo/downpipe removed.)

To fix, I just bent the power steering rack hardline down a little bit (using a tube bender so as to not kink) and was able to gain about 3/8" additional clearance underneath the spring clamp.  That should be enough to do the trick, because I determined that if the downpipe were to move down that far under acceleration, the downpipe itself would interfere with the front swaybar before the spring clamp made contact with the hardline.

It's good to figure out these little niggling sort of details...  

[MK3 GTD]

from what i understand of my 1.9s pump the governer idle spring (normally located on the end of the governer spring assembly) is moved to a seperate lever on the outside of the pump making it another seperate adjustment where that linkage from the cold start would tighten the spring and bump up the idle.

The residual pressure adjustment you were talking about i believe is the old idle adjustment and what ive found is that this adjustment can be lowered so that the revs will drop off when the accelerator is released under increased fueling, on the older pumps this meant the idle dropped as well but it seems with this setup that the idle can remain at a higher rpm and the residual would allow it to drop below the idle fueling level until the governor balances with the idle spring helping to reduce the rpm runaway effect.

Hard to explain and im not sure if i have the right idea or not but this is what ive found. At the fueling levels i have my car at, my idle sits at 950 rpm and the revs drop like a rock when i let off.

[type53b_gtd]

Another feature on the later pumps that is lacking on the earlier ones is an adjustment for "residual pressure" (which I still do not understand really.  Anyone want to take a whack at explaining that one to me?   )

Not residual pressure, but residual volume.  This is not a feature, but the sole function of the "previous" idle adjust on the newer pumps with idle boost.

The cold start nob has two detents on the later pumps.  The first detent is an idle boost - a few hundred rpm.  The second detent is an additional idle boost - maybe 30 rpm, and the cold start advance function.

The idle on these pumps is adjusted by means of a screw that effects the default rest position of the idle linkage on the side of the pump.  The governor arm rest position stop screw is used to adjust residual pump volume, and should only be adjusted if symptoms of high residual volume (surging, unadjustable high idle) or low volume (bucking, long cranking times) are noted.

The idle mechanism on the later style pump is more complex and prone to sticking with age, which results in erratic idle.

Drew

[fspGTD]

So the residual volume adjustment of the later pumps is just part of a more complicated adjustment for the idle stop position of the throttle input shaft lever?  It doesn't do anything else like adjust something directly inside the pump dealing with the governor characteristic, etc?  (A picture of this adjustment/mechanism would be great!)  Thanks for the clarification, guys.