lets forget the emissions

all i know so reading this great forum so far, that air pump is there to add some weight and use some hp. egr is there for to get intake look like dirty £#@.

if you cut those, how does is affect hp and mileage?

how's the stock prom? does it work fine after removing that junk?

p

 

EGR (exhaust gas recirculation) is used to introduce non-combustible exhaust gases into the combustion chamber to reduce chamber temps, thereby allowing use of more timing advance. Removing it will both set a code (turn on the ses lite), and also REDUCE performance by not allowing as much timing advance without getting into pre-ignition. (pinging)

Solution: burn a custom prom, without provisions for EGR, and compensate in the timing tables. (or, just live with it.....)

AIR pump is used to pump air into the exhaust system to aid in warming the cat convt. faster to make it more efficient and reduce emissions. It does not really contribute much weight, and only burns 1 or 2 horsepower. You can remove it and the computer just won't care. You will not notice any performance difference at all. But, it does clean up the engine compartment nicely...... You may, or may not experience premature cat convt. failure. I have heard it go both ways.... (my pump is still on the engine.....)

 

how about this? the lowest grade gas here is 95 octane. how can i disable EGR without getting service engine soon light? i'm not up to burning my proms yet, but surely i'd like to get something smarter for my ride.

how does EGR functioning? how can i cheat in a way that computer thinks engine is eating that smoke ***t even the EGR's disconnected?

p


[This message has been edited by pontiac (edited April 06, 2001).]

 

Pontiac,

That depends on the model year, engine, and fuel system. TPI engines used a temperature sensor installed at the base of the EGR valve to detect flow through the valve. If the sensor doesn't change (increase) when expected, the ECM will warn you with a DTC. A TBI engine uses the MAP sensor to detect the EGR operation, and if the MAP doesn't change pressure reading when expected, the same DTC will set. A carbed engine is easiest to "fool", since the diagnostic for the EGR is a lot less sensitive.

If you have a TPI or TBI, you'll almost have to alter the PROM programming to avoid the error code.

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Later,
Vader
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"I'm'a do Things My Way - It's My way or the Highway."
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The error code isnt consistent on the cars that use the temp sensor. If you have one of those, try disconnecting it first and see what happens. I wouldnt worry about the whole combustion/knock thing.

 

On a basically stock engine, there is little "benefit" to removing the EGR and a major problem in removing it.

Besides emissions and running more spark advance at part throttle, the EGR also increases gas mileage by effectively making a larger sized engine become a "smaller engine". If the EGR fills 25% of the cylinder with "inert gas" then your fuel economy will be increased because it is effectively behaving like a smaller engine.

Also, the EGR disables itself above a certain load/throttle position and does not function @ WOT. So disabling it does very little/nothing to improve WOT performance as it is already "disabled" and makes you burn more gas at part throttle since it is not filling the cylinder with "inert gas", plus you must use less spark advance. Trust me, you won't really notice the part throttle difference. And definitely notice nothing @ WOT.

After I got into PROM burning, I gained a whole new respect for the EGR and I am currently looking at ways to keep it operating as long as possibly and to fill the cylinder with as much "inert gas" as possible to achieve my goal of over US 30 MPGS. I am already at close to 30, but I want it to be CLEARLY OVER 30 US MPGs.

I have a bet with a guy with a V6 that I can make my car get better mileage than his. Right now, I know I can beat him. I just want to SEVERELY beat him (for gas mileage). As performance, he knows he's dead meat.

 

Glenn,

that's good news! i'd surely want to know your results once you tweak EGR and other values more.

this weekend i changed my winter ride to GTA. first tank of gas went down to 17mpg. oh yes, GTA spins around 245's smoking on dry asphalt with low 3000rpm and get some rubber on down shifts

when i came back on highway i still got poor 21mpg, even i drove most of the time 55mph with cruise on and no WOT accelerations. rpm's didn't went over 2500 and i hardly thouched the gas pedal. most of the time rpm's were over 2000 because of 3.27 gear, and i bet there's plenty of room to feed exhaust gases back, GTA didn't feel like there's not enough power to move on with 55mph...

some previous owners has been change thermostat to 160 degree one without any other mods... i'm going to change back to 200 degree or whatever the stock one is ASAP.

we went to measure 0 to 60 acceleration with my 2 brothers on board, we made just one run and it was over 7 seconds. GTA pulls nice and gently up to 5000rpm on WOT, but i noticed some pinging noise after 5000rpm. i think that's weird since weather is cold and i'm running with 95 octane gas...

i wish to make GTA run better and to use little less gas. who'd not?

Glenn, let us know how you're doing with tuning ECM.

later,


p



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Pontiac Trans Am GTA'89

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