Pukeloser@aol.com wrote:
: Hey fellas
: I just installed a hughes engines stage II TB because I couldn't wait to do
: it next week with the cam, rockers, manifold,DR timing chain. Anyhow, I got
: the thing on and the idle is now at 1000RPM, The instruction sheet that came
: with it says not to adjust anything but to check for leaks and/or replacement
: of the idle air solenoid. Does anyone have different wisdom than this? I did
: reset the computer.The TB was ported from a brand new TB from dodge so it
: came with all new sensors except for the little bpx that goes on the front of
: the TB with 2 torx screws, is this the idle air solenoid? should I replace
: it? or is there a different way of lowering the idle ?
The box on the front of the TB is the MAP sensor. What I would recommend
doing is to take the IAC motor off the ported TB and replace it with your
stock one. (The IAC is the solenoid at the back of the TB, which has the
little plunger on it.) If that doesn't solve the problem, then you're getting
too much air into the TB from somewhere else. Check around the base of the
TB where it seals to the engine to be sure there isn't any air leaking
underneath the throttle body (it would be sucked into the engine) You
may be able to use smoke or baby powder to check on that, if just feeling
for a leak doesn't turn up anything. Also, look down the bores of the TB,
and see how well the butterflies seal off the bores. Its OK to see some
light around them (assuming you're looking down the bores with the TB off
the engine of course), but they should be pretty much closed. There is a
stop which can be adjusted; as you are looking at the TB from the front
with the throttle linkage to your left, on the front/left of the TB there
should be a set screw which you can use to determine where the throttle
linkage rests. If the butterfly valves aren't completely closed, you
may need to back this screw out a little. (It might be covered by a plug
which you would first have to drill out and remove.) The instructions
from Hughes are correct in that the set screw is not the proper way to
correct a *low* idle, but if its set too high, the IAC plunger could
close off the IAC passage completely and still not be able to bring the
idle down enough. When adjusting the screw, be sure that it is the screw
which is stopping the throttle linkage, and not the contact of the
butterfly vavles against the TB bores. A test you might want to try
before messing with the screw is to seal off both bores while the engine is
running, by covering it with your hand, or a piece of rubber, etc. (Obviously
be careful of the serpentine belt system and the fan, and don't drop anything
down the TB.) :-) If you seal off the bores and the idle drops down to
normal, I'd say you found your problem. Also, with the engine running, put
your hand over the IAC cavity at the back of the TB and see if any air is going
down it. If not, its coming from somewhere else. If the set screw method
doesn't solve it, its possible there is a mismatch between the butterfly valves
and the TB bores, in which case Hughes should make it right.
Oh, also check to see that you didn't accidentally disconnect a vacuum
hose from the intake or something.
Basically, at idle, the VAST majority of the air should be going through
the IAC cavity. (There will be a *strong* vacuum at the IAC cavity.) If
the truck is idling and the air isn't coming through the IAC cavity, its
coming from somewhere else; somewhere its not supposed to be coming from...
You need to figure out where this air is coming from and stop it, in order
to force the air to enter via the IAC cavity, which the PCM can then
modulate.
Good luck! :-)
---Jon-
.---- Jon Steiger ------- jon@dakota-truck.net or jon@jonsteiger.com -----. | Affiliations: AOPA, DoD, EAA, NMA, NRA, SPA, USUA; Rec & UL Pilot - SEL | | '92 Ram 150 4x4 V8, '96 Dakota V8, '96 Intruder 1400, '96 FireFly 447 | `------------------------------------------ http://www.jonsteiger.com ----'
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