[xj-s] B-bank Air Intake

Hey folks
I just recently put 3 inch pipes on my air in takes without too much
trouble, then I was under the bonnet today while the engine was running
poking around to try to figure out why the engine was idling faster than
before the modification and what I would have to do to readjust it. I was
running down the list of things that can make the car idle fast, and when I
checked the plug for the air intake temp sensor to make sure it wasn’t
loose, I noticed that I could feel a good deal of suction at the enlarged
intake port and I was curious the same amount of vacuum was present on the
other bank but when I checked the other side there appears to be no air flow
into the intake, in fact it almost feels like it might be pushing air out
this remains the case even when the throttle in goosed. I know that I am new
to this but I didn’t see anything in the archives and my initial reaction is
to be a bit worried about this. So tell me am I being paranoid and this is
normal or do I have a problem?


'89 XJS

I’m still a bit on the newbie side, but have had a lot of chances to
poke around under my hood lately. :\ It occurs to me that even with the
air shut off to one intake (such as would happen if you put your hand
over the trumpet on an unmodded car), that air could still make it over
to that side through the balance pipe. The fact that the car is running
reasonably well means that the A bank is getting air from somewhere.

Make sure that the throttle linkage to the right side didn’t get
unhooked somehow. With the engine off, pull the right breather cover
and filter off and work the throttle pulley by hand and make sure the
butterfly opens and closes. Maybe the air filter is sitting too close
to the throttle body opening and the metal of the filter is blocking
some flow (would a missing air filter gasket cause that?). You could try
starting the engine with the right cover and filter off (after making
sure that there’s no crud in the area that could get sucked in, of
course), and see if air is being sucked in.

Would a blocked right throttle body cause a higher than normal vacuum to
be pulled in the balance pipe, thereby causing a higher than normal
vacuum at the ECU, which, thinking that the engine is under load, tells
the injectors to supply more fuel resulting in a faster idle? (How’s
that for a S.W.A.G.?) :slight_smile:

Hopefully, the older and wiser heads here will steer me straight if I
have given you bad advice.

Good luck.

1988 XJ-S H&E