Hello,

You probably saw my last post about the wierd heads on my Trans Am, so it begs the question "How much does the EGR system really do anyway?" I know that the GM engineers don't just put things there for no good reason, and the principle behind EGR is to lower the production of nitrogen oxides and combat preignition. But from what I could tell it only injects exhaust gas into one intake port. Am I wrong or does it only act on just one cylinder on one side of the engine. If it does-how the hell does it make a difference if one cylinder out of eight isn't producing a large amount of NOx? When I say make a difference I mean to the tailpipe sniffer at the inspection station...Again, if it doesn't make a difference then I should be able to install Vette heads and a PROM that eliminates EGR codes and pass an emissions test with flying colors right?

Thanks,

Matthew C. Hall

 

On TBI engines, the EGR is ported into each of the throttle bores, which feed through the intake manifold to ALL cylinders.

I think the intent was to re-circulate a small amount of exhaust gas with fresh air to reduce the amount of fuel needed for combustion under certain driving conditions (e.g. highway driving). This not only saves fuel but also helps lower emissions output when you factor in the extra air via the smog pump meeting this exhaust at the cat converter.

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92 Camaro RS, LO3, 5-spd, T-tops

Performance:
K&N Open Air Filter, Edelbrock performer TBI intake, Fastchip Prom, Timing +4 degrees, Centerforce clutch, Xact 8mm wires, SLP 1 3/4" Headers (coated), Flowmaster Catback Exhaust, Z28 Grille w/aftmkt fog lamps
Electronics:
Alpine 8030 Alarm System, Valentine One Radar Detector (How did I ever drive without one?), Pioneer DEH 7450 Head Unit w/6-pack CD changer, Pioneer DEQ 7600 Sound Processor, 2 Kenwood KAC-846 Amps powering 2 12" Pro Red subs, 2 Pioneer 6x9 and 2 MTX 4x6 speakers.
NEXT UP: TBI mods, 3.42 gears w/Torsen posi

 

Also, if you live in an emissions state that mandates a visual inspection, you may have problems if you modify the stock EGR setup in any way.

 

Aha...

So that's what those little slits in the throttle bores are. I was really wondering because it seemed like it only acted on one cylinder, but I knew the general's engineers had to be smarter than that. I think what I may do now is buy the Vortec head kit with the Vortec TBI intake-it's got provisions for an external EGR setup.

Thanks,

Matt

 

the little slits in the bottom is what you are talking about right? yes all but the egr and thermac lines are shared between both bores. (ot egr gas, btw, egr vacuum signal is not shared.)