Originally Posted by hailman13
update: i did what the tech said to do but i made new spacers and all that did was raise the idle and no effect on the cruise control. i then proceeded to check the vacuum line that goes to the cruise control unit all the way to the vacuum pod on the fire wall. the line has no cuts scrapes or brakes in it. i checked the one way valve and it is operating properly. and any adjustment to the placement of the cruise control vacuum pod pulls the cable which in turn raises the idle.
Ok, so all you have done so far is verify that the cable isn't binding
and the vacumn line has no leaks..but did you measure the actual
vacumn available for the two vacum valves at the rpm where the
cruise control is malfunctioning? Probably not. The Dodge shop
manual mentions a test for vacumn at idle and you need to pull at
least 10 inches of mercury in the first place..if you have less, you
may not have enough vacumn at road speeds to operate the thing
i guess with the added airflow from the intake and turbulence from the spacer changed the dynamics so much that the vacuum pressure no longer is enough for the cruise control to work properly.
You should buy an aftermarket vacumn guage and run it to a vacumn line
tap and run the line inside the cab somehow so you can observe the
vacumn at dynamic highway speeds. Right now, it's like trying to troubleshoot this symptom working blind.
Who knows what is happening to the vacumn levels inside with the manifold modification at road speeds when the cruise is engaged.
Question: what was the reason for adding the spacer under the throttle
body in the first place? Added performance or more HP at certain rpm?
unless i get a programmer that changes the ecm parameters for vacuum controlled components the only other option is to remove the spacer and see if the cruise control operates with the intake kit only.
well sometimes when there is a lot of confusion with modifications, it
is best to go back to square one to verify what is STILL working.
If you remove the spacer and go back to as much of an original intake manifold configuration as possible now, you should be able to prove
whether there is or isn't a problem with the vacumn servo.
Perhaps it's an "anomaly" that the spacer, or the other parts of the intake manifold mod kit are contributing to the type of symptom you are seeing with the cruise control.
Don't get frustrated, Do it one step at a time and use your trouble shooting skills.
1. Did the cruise on my truck work properly BEFORE I modified the
intake manifold? What was the vacumn (inches of mercury) BEFORE
I modified the throttle body?
2. When in calendar date/time did it stop working, if it worked properly
before the mod?
3. How would adding a spacer or moving the throttle body affect
air flow INSIDE THE MANIFOLD? What was the vacumn reading
AFTER the mods were done?
4. Where is the vacumn port (takeoff) on the stock intake manifold,
would that be affected by the throttle body mounted up higher?
5. How would the increased turbulence caused by the throttle body
spacer affect engine vacumn..obviously here a vacumn guage will be
necessary to prove that. ,
So far, from your description, all you have proven is that there is
no mechanical or vacumn hose connection issues. It's a good start,
but you need to dig a bit deeper.
its too dark for me to continue experimenting so im going to call it a night besides, i hear dinner calling me and a nice cold mug of so home made brown ale calling my name.
Ah! I love brown ale..and reds too. My favorite beers. have one on me
and maybe we can talk this thing through...I wouldn't go thinking about
reprogramming PCM algorithms..that's too expensive (and much too
"hit and miss", and makes it far too complicated for what may be
the TRUE CAUSE.
As a troubleshooter for many years on large computer systems..I have learned..
THERE CAN BE MANY SOLUTIONS TO A GIVEN PROBLEM...BUT ONLY ONE of
those..WILL BE THE BEST SOLUTION!