Continuing Problems 88 5KSQ

[Bernard Littau]

If you are a fix it yourself type, here is a great site for information on
the 5ktq.  You may also want to pass this along to your shop.
http://www.sjmautotechnik.com/trouble_shooting/trouble.html

Too lean usually means you do not have the typical blown air intake hose and
metered air leak -- that would make the system too rich.  You can't easily
get too much air into a CIS system, so if it is lean, it means not enough
fuel.  Usually, that means the ECU is confused by a bad input.  Very rarely,
it can be the fuel pump or fuel filter, but these sorts of problems tend to
manifest themselves at high throttle and high boost first.

Since you replaced the multi-function sensor, I would start with that as the
likely culprit.  Even new parts sometimes are bad or fail immediately.
There should be some basic tests for the multi-function sensor on the SJM
web site.  If the ECU is getting a hotter temp than reality, it could be
confused into a lean mix.  Sorry, I forget if the ECU gets its temp from the
multi-function or one of the other sensors, so you may need to look that up
on the SJM site, or someone with a more recent memory might chime in :-)

I'll amplify on what Steve said: The mixture screw on a 5ktq never needs to
be touched, the problem is always somewhere else :-)  You really need to
rule out everything else before you adjust the mixture screw.  Check all the
input sensors and switches to the ECU.

Best,

Bernard