Ok, Ive got the tbs were in front of me...Im cleaning em....
So I figured, has Nissan *really* put a coating in there to seal up its
throttle body??
So I dig deeper....nothing in the factory manual about adjusting these
flaps or replacing a coating or whatever. Just a very comprehensive
page about setting the optimum length for linkage tierods...clue 1
So I dig deeper...wouldn't there be a replacement can of goo from Nissan
for this perhaps maybe 88 dollars for a 150g of this stuff?
I mean the "black coating" comes right off with your hand....no harsh acids
or 190 proof grappa either....
Well Tomei have a throttle coat...A quick glance at Tomei's site tells us the
entire procedure of putting goop on....apparently it improves throttle response
(literally to pedal response).
http://www.tomei-p.co.jp/_2003web-catalogu...hers_gauge.html
It says NOT to put it on the main body...only the flap. Curious, so if it does any
sealing it is relying on the throttle flap to do the sealing...Makes sense, well thats
what the job of a throttle flap is when closed! However how big a gap is this meant
to close? Its not intended for that primarily....Btw primary ingredient is
molybdenum disulphide.....clue 2
From what I can see, some people are over-zealous with their cleaning
attempts, flexing the throttle shafts and somehow damage the throttle shaft seals
on the sides...or leave some dirt right up the shaft seal area which acts like a wedge
holding the tb open slightly....These are delicate precise things...
Well then a good clean and a reset (if required is to be done). It is ideal that
all the flaps seal. Also note that there are THREE air bypass routes
for idle control. Two in the IAV (a bleed screw and the solenoid valve itself and
a supplemental air path in throttle body 1.
So it stands to reason that:
- The factory tbs need to be clean to operate properly.
- There is no sealant that nissan use at the factory. There is no empirical evidence to
demonstrate its being applied aftermarket.
- Cleaning the throttle bodies does not result in idle problems however
improper cleaning may cause idle problems.
The throttle stop screw for each throttle body requires some time to
reset...not long...just a few minutes to get the position right. It pays to
use some moly disulphide grease (CV Joint grease) on the flap edges and the
stem while setting it. Once set, there should be NO gaps visible....these
are precision NC machine surfaces and hardened....flaps are batch stock
and are "best fit" however are matched to each bore and adjusted to seal.
Of course there are going to be factory errors, minor warping due
to peak engine temperatures...so perhaps some correction is required...
So moral of story....
1) Clean well, with toothbrush, metho, perhaps a zap or two of throttle
body cleaner for stubborn bits....
2) Check seals.
3) Lubricate.
3) Reset stops (if required).
Then follow the linkage tierod setting procedure in the RB26 manual.
(In R32 GTR factory manual it starts on page EN37).
Then final idle adjustment should be done using the IAV bleed screw.