92 and 98 Throttle Body Map + EGR Vacuum Diagram

In order to figure out why I was getting a check engine light,
I mapped my 92 and 98 TB. Below is my hand written diagram. I also
included the diagram of the EGR vacuum lines for reference.




This is a picture I drew to map the 92 and 98 TB's. This should be helpful for
anybody doing the TB swap on a 98 or 99 vehicle. On 95-97 I believe that there
are three ports on the top. I am not sure if you use the same ones or not?
NOTE: (P - 92) = (E - 98) and (A1/A2 - 92) = (A - 98). If you use A1 cap A2.




This is a picture of the EGR Vacuum lines. This is helpful to see how the EGR
works. I needed to use this when I made my Intake Pressure Tester. I will add
some of the e-mails I have sent lately.




Hello All,

I made some very interesting Idle discoveries yesterday
evening. First a little history on the car...
1998 Mits Eclipse GSX with 1992 head, intake, TB...

The idle problems that occurred after the head swap...
Stock ECU: The car would cold idle fine... and worked
fine until I stopped the car for a while. Then the car
wanted to idle at 400 rpm... I found if I pulled the
A/C relay, and ran the fans, the extra load idled the
car at about 750 rpm. (I figured that the idle problem
was due to the larger ports on the head, larger TB, or
larger injectors)
ProEFI: I have been playing with the ProEFI for a couple
of weeks now. I had a similar problem as with the
stock ecu, but it was much worse. To the point where
the car would not idle at all after it had been stopped
for about 10 minutes. I was pulling my hair out trying
modify maps... Then I remember there is 3 ways the
TB controls air going into the motor... IAC Stepper,
BISS, and Temp Control Bypass. (not sure if that is
what it is really called)

The real problem... and fix...
When I had done the head swap, and put the 92 TB on
the car, I decided to bypass the water lines to the TB.
I just ran from the Thermostat housing down to the
return pipe, and capped off the inlet and outlet on the TB.
I figured that I would gain some extra power by not having
the TB get Coolant Temp hot... I never even consider that
it would affect the "Temp Control Bypass" on the TB...
What was happening... I would adjust the BISS to idle
the car perfect, as the TB was cold, but the motor was
hot. When I would stop the car for more then 10 minutes,
the engine compartment temperatures would heat the TB
and cause the "Temp Control Bypass" to close... cutting
off the air to the motor. This would cause the car to
die.
Last night I returned the coolant lines back to the TB.
It was a night and day difference... As the motor started
to heat up, so did the bottom of the TB, which started to
drop the idle fast... In order to keep the car idling, I needed
to adjust out the BISS screw.. I actually needed to adjusted
it the farthest I have ever had to adjust it, which tells me
the "Temp Control Bypass" was always letting air bypass...

Now that I have taken the "Temp Control Bypass" out of
equation, I will modify the IAC Stepper table, and adjust
the BISS to idle the car under all temperatures....
It is now time for the real fun to begin...

-Shawn




Last week was the TB discovery this week is an EGR discovery.
The car: 98 GSX with 92 TB, Intake Mani, Head...ProEFI

I decided to make a pressure tester. I will take some pictures
and post it to my web site. It is really easy to make and a good
tool to have.
So I hook up my IC pressure tester to the inlet on the turbo, and
start to apply pressure with my air compressor. Very quickly I
discover that it will only get to 2 psi of pressure!!! I also notice
that it sounds like my turbo is leaking the pressure into the
exhaust system. I am not too happy about this, but need to
confirm the turbo is the problem. I remove the lower IC pipe and
hook it back up... again only 2 psi of pressure.. Test the turbo..
it will hold pressure but leak a little around the 'C' clip in the back.
So now I am wondering why I can't make the pressure and
I can hear it in the exhaust system. I reconfirm that I have the
car set to TDC - top dead center - and it is..
So now I am at a point where it can only be 1 of 2 things. EGR
or I have a bad valve. EGR is easiest to test... I had made a
block off plate, but just never installed it. I decide to cut and
scratch up my hands by putting in the plate.

Time for dinner... so I pull out my factory manual for some light
reading... I discover that (on the top of the TB) 'A - 98' which
corresponds to either 'A1 or A2 - 92' is connected to the
bottom of the EGR diaphram and T's off to a "Purge Control
Valve" and bottom of the "EGR Solenoid". 'E - 98' which
corresponds to 'P - 92' goes to the "EGR Solenoid" then to
the top of the EGR diaphram. I realize that with no power to
the solenoids, the pressure will cause the bottom of the
diaphram to lift and open the EGR.
(I have a diagram I made mapping a 92 and 98 TB. I will
scan it and post it to my site)

So with the block off plate in place, which would have been
just as easy to disconnect the 'A/A1/A2' hose... I re-ran the
pressure test at the turbo. This time I got it to go up to 26 psi
of pressure. No more leaks into the exhaust system! No leaks
in the IC piping or Intake Manifold... The only leaks are in
the compressor housing of the turbo. It seems like the back
off the compressor housing where the 'C' clip is. Oh.. and one
of the bolts in the face of the housing. (Frank II Turbo) They
are not bad leaks, but noticeable. I am not sure if I should worry
about them, because they may be on the vacuum side of the
compressor.

-Shawn