NOx problem solved

[John A. Heer]

Frank:

I won't bore anyone with my opinions about various exhaust sounds (HKS
cat-back vs. Dynomax, etc.) because it is all in the ear of the
listener.  Whatever volume and tone you like might be pure hell on
another SE-R owner.  I happen to like a minimally aggressive sound, but
somewhat stealth.

However, I'll take a stab at the other questions.

The back pressure transducer (a/k/a "BPT") on the 91-93 models is
sitting up high behind the injectors.  The BPT and the EGR valve look
like two same-sized saucers or discs with small rubber hoses connecting
them.  The BPT is the one on the driver's side.

All I did was install a bypass tube from the EGR "saucer" around the BPT
"saucer" and eventually leading into the EGR metal tube which runs
toward the front of the engine bay.  Does it affect drivability?  You
bet it does.  I'm sputtering something fierce when I try to steady
throttle around town.  Highway driving is fine, but start-stop is no
fun.  Performance?  no benefit, other than passing emissions for NOx
here in Ohio.

I think the BPT looks for 1.7 somethings (forget the unit of
measurement, maybe pounds of pressure/vacuum), and I could only achieve
1.6 somethings with my current exhaust.  So, yes, less backpressure
makes the BPT prevent the EGR from working.  No EGR or faulty EGR
usually results in high NOx emissions.

John
93 SE-R
98 SE
91 SE-R (R.I.P.)

-----Original Message-----
From: Qualudia101@aol.com
Where is the transducer located? How do you disable and
does it affect performance if disabled?Had never heard of this.
Are you saying that the less backpressure exhaust you
have the more likely the EGR will screw up, and could cause
emission passing problems with NOX?