intake manifold tube egr

[PhantomZ28]

hey,
i'm about to do the lt1 oil leak repair. do i need that flexiable pipe in the back of the manifold that causes the leak? cuz i want to rip it out and get coveres made for the holes. just wondering

[wolfdogs]

funny you asked this.......i ve only seen a few of the solid pipes on em........my CompTA being one..... i like the flex pipe better.. you can move it away from the manifold corner..you cant with the solid one. our hawk has the flex pipe.

[PhantomZ28]

hey first of congrats on the TA sale!

but i think i dindt phrase the question right.
i want to knokw if i need to keep that pipe in the car? can i just rip it off the intake and exhaust manifold and plug up the holes? or is it needed to help the car work and not produce the ses light?

basicaly no pipe or keep pipe and move it away?

[PhantomZ28]

anyone??

[Injuneer]

The corrugated pipe supplies exhaust for the EGR system. Although the EGR system's primary purpose is to reduce emissions.... specifically oxides of nitrogen (NOx).... it offers the fringe benefit of reducing the possibility of detonation when lugging the engine at low RPM in too high a gear. Probably enhances fuel mileage slightly too, since it is in effect the equivalent of a "displacement reduction" system.

There is no performance loss from EGR... it only operates at part load. Never at idle, never above 3,500RPM, nver at WOT.

If you remove it, what happens depends on what year your car is (pays to have a "signature", with info like the year of your car, tranny, mods, etc. so people can give you the correct answer). 93-95 OBD-I generally do not see a code/SES light when EGR is deleted. It can happen, but the diagnostic does not seem very sensitive. If you have a 96/97 OBD-II, the code/SES is a 99% certainty. The EGR operation needs to be "programmed out" of the PCM.

The suggestion included in Ken C's intake manifold repair procedure is to bend the tube away from the intake manifold, and then put some heat wrap on it to minimize the heat-up on the intake. I have kept the EGR intact even with my stroker, and never had a problem with the intake manifold leak.

[PhantomZ28]

the thing is the tube is as far away from the intake as possiable and it still leaked. i have a 97 lt1 but i also have the hypertech pp3. also if it says to have no performance gain then how can it reduce emmisions so much? and how can the pmc know the tube isnt their. or wil teh emissions be so intence the pmc will go nuts. would o2 simulators help?

[PhantomZ28]

hey i just noticed 2 egt intakes in the back of the intake manifold. is it the egr valve outlet that would cause the ses ? cuz i honestely dont see how a little pipe can cause the ses



the one on the right i'm blocking off

[Injuneer]

The one on the passenger side is the connection for the corrugated riser tube. The one toward the driver's side is where the EGR valve bolts on. Where do you see a second "intake"?

You get a "code/SES" because when the PCM tells the EGR valve to activate, it looks at the MAP sensor for a change in intake manifold pressure. If you don't have any source for exhaust gas connected to the manifold, the PCM isn't going to see the pressure blip its looking for.

You still haven't mentioned what year your car is, so the debate over what sets a code/SES is moot. Is this some sort of secret ?

[PhantomZ28]

ok i have a 97 but i'm still confused about the pipe. its always open. erf i'm gona block it off but keep the pipe in to see if i get any codes

[Injuneer]

The "pipe" is always open... it supplies the exhaust to the EGR valve. The valve has a "pintle" that opens and closes to allow the exhaust from the pipe to flow into the passages in the bottom of the intake manifold. If there is no supply pipe, there will be no exhaust flowing into the intake. The PCM looks for the manifold pressure change when this happens.... if there is no EGR, the pressure will not change when it is supposed to.

Cut a small plate out of a soda can and sandwich it between the pipe flange and the back of the manifiold.

[Bond Hawk]

Fred, if the MAP sensor reads the intake manifold pressure and tells the PCM when the EGR valve opens and closes, what affect does a breather on the crankcase have? I know you don't think the breather is required to eliminate the intake manifold leak, but it seems to help relieve some of that pressure.

[PhantomZ28]

done and done
ok i riped off the tube and put 16 guage steel cutout plates over the holes and have been driving it for about 2 hours staight. and no ses!! and i DO have a 97 so no more hot pipe for me

[Injuneer]

The breather vents the crankcase preesure, if any. That's completely different than the intake manifold pressure.

I still do not think a healthy engine, with a correctly operating PCV system will ever generate any pressure. The vent line on the passenger side valve cover is there specifically for that purpose.