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I have an early 86 coupe. I am installing a set of hooker headers 2149HKR. I have two questions. Do I have to change the EGR tube to a later C4 87-89? Should I weld a bung into the collector for the O2? Instead of using the one in the primary tube.
From: Las Vegas - Just stop perpetuating myths please.
All the EGR vlv needs is an exh gas source and any exh tube will do if u are willing to drill and weld into your new headers. I dont expect the smog inspectors will know the difference if not in the stock location as long as the EGR is functional. Ok i googled hooker headers 2149HKR and see they have the EGR fitting so u must be asking for the tube between header pipe fitting and the EGR vlv. To me this means anything that fits is good - even using some bendology.
Yea the O2 sensor is more representative in the collector though it takes longer to heat up to operating temp. Do u have 2 or 3 wire O2 sensor? 3 wire is self heating. Long tube headers with the O2 in the collector can be inaccurate unless heated. I believe its fairly easy to convert to 3 wire if need though i have not done this.
Those headers use the later style egr pipe. You can't use your early one. Someone on here would probably buy it off you though since they aren't made anymore.
I ran mine for about two years with the o2 in the primary tube and the egr plugged off with a nickel under the egr plate. I just left the sensor plugged up and it was sitting on top of the intake. Never did get a check engine light.
2020 Corvette of the Year Finalist (appearance mods)
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Yeah...The issue comes down to emissions and AFR accuracy. The more cylinders you "monitor", the more representative the "sum" of residual O2 will be. If your motor is running correctly (even) from injector-to-injector, monitoring just one cylinder is sufficient. OTOH, even monitoring 4 cylinders (via the collector) doesn't provide feedback from the passenger bank.
That's why monitoring just one cylinder will work. When it's not running right, you'll probably notice. (smoke, fumes, smell, miss, etc..)
EGR prevents the emission of NOX fumes at higher temps. It won't throw a code or cause running problems until sufficiently hot that you MIGHT notice a miss -- but it would need to be really hot. That said, adapting and maintaining the EGR isn't a bad idea. If you run a cam with more overlap/duration, it will accomplish the same function (diluting oxygen with burnt fumes).
Controlling [upper] engine temps is another good way to limit the loss of EGR function.
If you have cast iron heads then you don't need the EGR tube. The exhaust passages are cast into the heads and intake manifold (surprised me when I saw that the last time I took it apart). The dark area in the center top of this picture is the EGR connection to the passenger side head (it looks like it connects to the center passage but it doesn't):
Last edited by Cliff Harris; Jan 11, 2015 at 12:32 AM.
Headers with EGR
