[mwebb]

my 1995 VW jetta 3 with ABA engine did have EGR - thank me very much .
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Using Pico 6 software and scope with a Fluke PV350 pressure transducer in #1 spark plug threads , zeroed to ambient barometric pressure prior to the capture ....

here is a running compression waveform , captured with pressure transducer in the spark plug thread , engine at idle running
Honda D16Y7 1.6 sfi engine , no EGR No variable cam timing
but it has EGR now .

the upper horizontal cursor is 0 psi or ambient barometric pressure
above the line is pressure
below it is vacuum

note the two vertical cursors around 325 and 357 degrees
showing a 5psi pressure spike in the combustion chamber as , the exhaust valve has already closed and the piston has not yet reached 360 degrees TDC and now

when the intake valve opens , that residual 5 psi of exhaust gases will be added to the intake air as EGR

on this capture it is a problem related to incorrect camshaft timing
but
it shows how engines with no EGR valve and variable cam timing can have EGR function
without an EGR Valve


to learn more about EGR
[QUOTE]http://autospeed.com/cms/title_EGR-C...7/article.html
look also at the refrences listed at the end of the article
study and learn