'87 5ktq low boost issue

Ben Swann benswann at comcast.net
Thu Nov 9 08:51:19 EST 2006



A properly programmed chip does indeed provide boost control via. wastegate
frequency valve.  A wastegate spring can augment or over-ride this control, as
can a pressure regulation device that can substitute for the frequency valve.
The chip has an overboost value programmed into it, so using to much
additional wastegate spring would cause a fuel pump cutout.


If I recall the original post, Cody's setup is not working as it should.  With
or without a spring a QLCC chipped engine should see at least 1.7 and a well
sorted engine will see 1.8Bar.





[Date: Wed, 8 Nov 2006 23:24:49 -0500

From: "E. Roy Wendell IV" <erwendell at mac.com>

Subject: RE: '87 5ktq low boost issue

To: quattro at audifans.com




As I understand it, the MC1 boost system isn't closed loop control so just
installing a chip doesn't result in increased boost. Rather, it allows for
increased boost by raising the cutoff point and increasing the mixture control
duty cycle. The boost map is simply a lookup table of rpm and the related duty
cycle, not a boost target. It was designed to flatten the torque curve and
avoid too much boost at the max VE point for the engine and thus avoid


So my point is, maybe you are experiencing normal operation for this mod?
AFAIK this is why MC1 boost mods are usually a chip and spring combo. I
realize you have boosted the heck out of the MC1 in the past but I recall that
you were using some sort of air bleed valve at the time.


Roy Wendell

erwendell at mac.com

Too many type 44 tq

A pair of MR2s]

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