I have a '96 B2500 with 5.9. About 2 years ago we had a new/rebuilt
(jasper) engine put in it because it had a rod knocking. Not too long
after that we noticed the idle was a little rough. Over the year or
two it has gotten to the point of being real rough. Idles smooth while
cold, as it warms it gets to a point where it increases 300 RPMs or
more then drops off.
The manual says check vacuum first. I did this today and found a
busted line from the throttle body to some kind of solenoid. I
replaced that line, the PCV, and air filter, the condition is still
After some research and study I think the MAP or Intake Air sensors
could cause my problem. Before outlaying that kind of money to see if
a replacement would work, is there anything else I should be concerned
Once again, another great question, but Nope, no codes.
I did unplug the MAP while it was running, and boy did that screw
things up. I suspect that the MAP might be fine so now thinking about
the Intake Air Control valve.
So here is what I've done so far. I took out the Intake air valve and
found that it was all crusty and carboned up, also it had a rattle to
it. I got a new one and put it on there and it seem to help for a
little bit, however, the idle is much lower and much more calm. So I
think I am getting closer even though it still is pulsating.
It could be my imagination but it seem to have a little better takeoff
My wife is out now getting a MAP sensor and an intake air temperature
sensor. I will put both of those in and see. It will be my luck that
it is the throttle position sensor.
You may not like it but you asked.. <BG> I really hate guessing on these
symptoms any more. Unless it's something really common a wrong guess can get
expensive. Would this not be a good time to have someone/mechanic/dealer put
a scanner on it and actually diagnose the problem before throwing more parts
at it??? It may be cheaper in the long run.
No offense intended of course.....
I guess I am done throwing money at it today. I have replaced the Idle
air valve, the intake air temp sensor and the map sensor. Although it
has surely made a difference, the rushing is still there. I did take
the time to clean the throat area of the of the throttle body really
well, nice and shiny. I also ensured all the rubber vacuum lines are
replaced. I have tested the voltage to and from the TPS and it is
good. So unless it is a fuel filter, fuel pump or a crack somewhere I
The thing that gets me is that now the thing has way more torque than
it has ever had since I have had it and after the engine change.
Something I discovered because now it has get up and go, it hits the
Rev limiter before it shifts out of 3rd gear. Going to have to have
that looked at.
So now it is to get ball joints, shocks, springs, and the air
conditioner serviced (got a hole somewhere). Also, I am going to have
to find a steering column coupler.
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