Engine Lets Talk Pcv/egr Delete.

CarMichael Angelo

my rearend will smell so minty fresh,
15 Year Member
Nov 29, 1999
Birmingham, al
I've been doing a little bit of research, and true to every forum search, there is conflicting information out there, so I thought I'd bounce it around here before I committed to starting the car with, or without the either of the two systems.

PCV: I'm pretty sure I'm gonna delete the factory PCV, and run a breather on each valve cover on the Cobra. There is an issue w/ these cars sucking oil past the factory system under boost, and after removing the intake and plenum, mine is the same.
The detractors to doing this appear minimal,...some say that breathers are not as efficient as a PCV system, and will leave oil residue everywhere, as well as contaminate the engine oil faster. Others stipulate that there has to be vented catch cans with -10 hoses ran in order to control the oil spewed from the valve covers.

I already have the breathers on each valve cover, I had them on the last motor. I had no oil residue on that engine, but then again it didn't have a blower on it.


I don't like that hot assed tube back there. There are waay too many hoses and wires in this cramped ass engine compartment to keep a tube that gets as hot as that thing does back there. There were several crusty hoses that showed evidence of heat exposure because of it as well.
I know that once removed, there will be a C.E.L. associated with it, but it can be turned off in the tune, so I'm not worried about that aspect. This car does not have cats, and Alabama doesn't inspect, so there is no worry there either. ( I do intend to add the cats back though, purely to clean up the exhaust.....I know the EGR delete will add to that)

What I am concerned about is that some say that not running it is actually detrimental to the combustion process, and will actually increase combustion temps when deleted. Kinda goes against my rationale........How does getting rid of a tube that's purpose is to introduce hot air ( in the form of already burned exhaust gas) into the intake stream, end up being detrimental to the combustion process?

If there was any other way to make this system work, I'd probably keep it.:shrug:
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Some basic theory to clarify how things work is in order…But only guaranteed to be correct for a 5.0 Pushrod Fox engines.

EGR System theory and testing

The EGR shuts off at Wide Open Throttle (WOT), so it has minimal effect on performance. The addition of exhaust gas drops combustion temperature, increases gas mileage and reduces the tendency of the engine to ping. It can also reduce HC emissions by reducing fuel consumption. The primary result of EGR usage is a reduction in NOx emissions. It does this by reducing the amount of air/fuel mixture that gets burned in the combustion process. This reduces combustion temperature, and the creation of NOx gases. The reduced combustion temp reduces the tendency to ping.

The EGR system has a vacuum source (line from the intake manifold) that goes to the EVR, computer operated electronic vacuum regulator. The EVR is located on the back of the passenger side shock strut tower. The computer uses RPM, Load. and some other factors to tell the EVR to pass vacuum to open the EGR valve. The EGR valve and the passages in the heads and intake manifold route exhaust gas to the EGR spacer (throttle body spacer). The EGR sensor tells the computer how far the EGR valve is open. Then computer adjusts the signal sent to the EVR to hold, increase or decrease the vacuum. The computer adds spark advance to compensate for the recirculated gases and the slower rate they burn at.

Thanks JR,...I figured you'd be here sooner or later to clarify that for me. I attempted to put the EGR hardline back on this afternoon, but that is gonna be a little more difficult than I had hoped. I'll probably end up cutting the damn thing into two sections, flaring it and putting in a union so that I can put back what was already on.

Hmm......now I know why they call me "do it twice Mike.":shrug:
The pipe is probably stainless steel and will be hard to flare without a really good flaring tool. You'll need a stainless steel union and flare nuts. Check out places that make hose and tubing assemblies in your area for parts and help
I deleted mine, capped off the manifold and turned it off in the tune.
Don't notice anything detrimental.

I run the pcv valve, didn't have any oil in or under the intake last time i took the intercooler out.