EGR valve, Where?
Thread Starter
Racer
Joined: Mar 2008
Posts: 254
Likes: 0
From: Perth W.A
EGR valve, Where?
Hi
ok i thought that the egr valve was just down from the dizzy!?
but all i can see is the pipe w/heat coating, that goes from inlet manifold to exhaust!
Is the EGR valve somewhere else on a 90 model?
thanks
also what exactly does the air pump systems do? is there any benefits to removing it?
ok i thought that the egr valve was just down from the dizzy!?
but all i can see is the pipe w/heat coating, that goes from inlet manifold to exhaust!
Is the EGR valve somewhere else on a 90 model?
thanks
also what exactly does the air pump systems do? is there any benefits to removing it?
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Under the plenum, on top of intake base.
The AIR pump intoduces fresh air into the exhaust and catalytic converter on cold startup so that the converter comes up to operating temps and starts working faster. The rest of the time the solenoid valve cuts off the flow to the exhaust and it does nothing but spin with the motor. If you have bi-annual smog, you'll fail visual without it.
The AIR pump intoduces fresh air into the exhaust and catalytic converter on cold startup so that the converter comes up to operating temps and starts working faster. The rest of the time the solenoid valve cuts off the flow to the exhaust and it does nothing but spin with the motor. If you have bi-annual smog, you'll fail visual without it.
Last edited by 86PACER; Nov 16, 2009 at 03:00 AM.
Thread Starter
Racer
Joined: Mar 2008
Posts: 254
Likes: 0
From: Perth W.A
Under the plenum, on top of intake base.
The AIR pump intoduces fresh air into the exhaust and catalytic converter on cold startup so that the converter comes up to operating temps and starts working faster. The rest of the time the solenoid valve cuts off the flow to the exhaust and it does nothing but spin with the motor. If you have bi-annual smog, you'll fail visual without it.
The AIR pump intoduces fresh air into the exhaust and catalytic converter on cold startup so that the converter comes up to operating temps and starts working faster. The rest of the time the solenoid valve cuts off the flow to the exhaust and it does nothing but spin with the motor. If you have bi-annual smog, you'll fail visual without it.
I think mine is disconnected! will have to check!
Well sounds as though the air pump can stay then! it's only doing good! and plus to remove them, it is only replaced with a pulley anyway, right? so there is no point, except for space!
So what is the pipe from inlet to exhaust doing?
thanks
Intermediate
Joined: Mar 2009
Posts: 46
Likes: 0
From: Berwick Pennsylvania
The insulated pipe from exhaust to intake is part of the EGR system. It transfers hot exhaust gases back through the combustion process (Exhaust Gas Recirculation). This has the effect of reducing combustion temperatures, which lowers emissions and prevents preignition (ping). The exhaust gas flow is regulated by the EGR valve.
-jr
-jr
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Yes, unfortunately unlike the Camaro TPI's that can simply remove the air pump and run a shorter belt to take up the slack, we have to have some type of pulley there to keep the belt up and off the power steering pulley due to the routing.
The eliminator pulleys are around $150, which I think are overpriced for what they are. And again, if you have to deal with emission checks, you'd have to keep your stock air pump on hand and swap it back in to pass.
The eliminator pulleys are around $150, which I think are overpriced for what they are. And again, if you have to deal with emission checks, you'd have to keep your stock air pump on hand and swap it back in to pass.
Last edited by 86PACER; Nov 16, 2009 at 09:29 PM.
Thread Starter
Racer
Joined: Mar 2008
Posts: 254
Likes: 0
From: Perth W.A
The insulated pipe from exhaust to intake is part of the EGR system. It transfers hot exhaust gases back through the combustion process (Exhaust Gas Recirculation). This has the effect of reducing combustion temperatures, which lowers emissions and prevents preignition (ping). The exhaust gas flow is regulated by the EGR valve.
-jr
-jr
but...
as the engine is designed to run quite hot anyway, shouldn't it be irrelevant to have this pipe? also how does circulating hot exhaust fumes back into the cylinder reduce the temps? you would think it increases temp!
well what about earlier vettes, that didn't have all this emissions/pollution gear? did they have high combustion temps?
and pinging?
86pacer: thanks yeah i won't be changing anything like that on mine!
though if doing a headers swap, do you guys pipe in the air system?
most headers i've seen don't look like they have a fitting for it!?
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
You can get them with our without. When I run my long tubes that don't have air tubes, I remove all the AIR crap except the pump. It really clean up the engine.
Intermediate
Joined: Mar 2009
Posts: 46
Likes: 0
From: Berwick Pennsylvania
Phantom Vette 1 said:
All of this came about because of Federal regs that required that gasoline be reformulated to eliminate "lead". If you recall, tetraethyl lead was used as an additive and octane booster. In the early 70's, we saw the introduction of the catalytic converter, AIR pumps and plumbing, and EGR to deal with emissions and the less powerful gasoline available. Compression ratios were also reduced to help manage the spark knock. We've had to incorporate work-arounds like this for a long time now, and the introduction of ethanol to the fuel mix only exacerbates the problem.
-jr
as the engine is designed to run quite hot anyway, shouldn't it be irrelevant to have this pipe? also how does circulating hot exhaust fumes back into the cylinder reduce the temps? you would think it increases temp!
well what about earlier vettes, that didn't have all this emissions/pollution gear? did they have high combustion temps?
and pinging?
well what about earlier vettes, that didn't have all this emissions/pollution gear? did they have high combustion temps?
and pinging?
-jr
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Instructor
Joined: Sep 2004
Posts: 216
Likes: 4
From: Linton Indiana
Yeah, we used to run 11:1 compression on the street. But that was then. You can also remove the A/C pump when you remove the air pump and then you can use a shorter belt. Plus you can get rid of the tensioner. If it's like most Vettes you don't use it for daily transpo anyway.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
filling the cylinder partially with exhaust gasses displaces some of the fresh air with a "filler" gas (exhaust) and since the filler does not burn, the effect is to burn the intake air competely, reducing the total combustion temp by reducing the amount of readily burnable mixture, eliminating pinging, or preignition.
In effect, a cooler burn.
In effect, a cooler burn.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
And the air pump doesn't quit pumping air to the CAT after warm up. For an L98, air is directed to the Headers first and the extra oxygen, when combined with the rich, cold mix, is like an afterburner. That extra burning (heat) gets the O2 up and running faster. With Closed Loop, air is diverted to the CAT and keeps pumping to the CAT until WOT or when you let off the gas because if it kept pumping during decel, the extra air would light off the rich mix it suddenly gets; ie, it'll backfire (which is what Vegas and K cars use to do before some Dilbert redesigned it). If you want to do without it, you should consider a heated O2 and a more efficient CAT. Of course you will need to do something about the Checkvalves in the headers - leave them or stick whatever pipe plug you can find at Home Depot or Lowes in them. Rather ghetto in my opinion, but it's your Vette.
