Subject line says it all. Will I pick up any power if I remove and cap the EGR port on my 88 coupe with a 2.5 "DUKE" engine.

I have to remove it to replace my valve cover gasket and just wanted to know If it was worth leaving it off.

Thanks

Rob

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qwikgta@yahoo.com
88 T-Top coupe, 65K, Header no Cat, 16" GTZ rims, short shifter, swaybar, open element air cleaner, hood vents.
http://robsfieroproject.homestead.com/index.html
http://vafiero.com

Your engine is designed to work with it. You will have to fight with pre-ignition due to increased combustion chamber heat. I would recommend having it in working condition.

If you remove the EGR, you need to compensate for the increased manifold pressure which could cause a lean condition resulting in higher head temps and possible pinging. With the older Dukes and the V-6's this is easy to do by advancing the ignition timing 2 degrees and using premium gasoline. (91 or better octane) On DIS engines you need to either change or re-program the PROM in the ECM. Hypertech use to have a "stage III" chip (don't know if they are still available) that requires the EGR to be removed, low temp fan switch, low temp thermostat, and a less restrictive exhaust. This had all the changes required to properly remove the EGR. Removing the EGR and adjusting for it is suppose to gain you somewhere around 5-8 horsepower. I don't know how true that is, but I do know the engine will have better throttle response and run better. Also since the intake system runs slightly cooler (not sucking in hot gases) the economy (gas mileage) also increases.
There is also the issue of emissions. Without the EGR the NoX levels will be high. Some states don't check for these unless the car is 1994 or newer.

The EGR is closed above about 25% throttle anyway.

The ECM controls ignition timing in closed loop, so what effect would changing the base timing even have? Even if it does have an effect, advancing the timing would be the exact opposite of what would be needed to prevent detonation. Like Terryk said above, the EGR does not even operate during acceleration or WOT, so removing it would have little or no effect on performance. If increased horsepower can be obtained from removing the EGR, this is the first I have ever heard of it. Would not the hp increase only be realized during idle or cruise conditions when the EGR would have been operating, or is there some other factor involved?

[This message has been edited by 00lE (edited 06-22-2001).]

at idle or cruise HorsePower is not defined - horsepower is only measured at throttle WFO - how else could it be?! What does half throttle mean? 1/4 throttle?!

or to put it another way, who cares how much HP you have with the throttle plate closed or 1/4 open? the only one that counts is when you want more and thats all there is: WFO.

I have the EGR blocked off on my 88GT and it runs much stronger since. Think about it... How does stuffing extremely hot exhaust gas into your intake not rob you of power?

quote Originally posted by Ken Wittlief: at idle or cruise HorsePower is not defined - horsepower is only measured at throttle WFO - how else could it be?! What does half throttle mean? 1/4 throttle?! or to put it another way, who cares how much HP you have with the throttle plate closed or 1/4 open? the only one that counts is when you want more and thats all there is: WFO.

Well figuring that 3 or 4 HP at cruise a 1/4 throttle you will see a smidge better gas mileage but since you will need a higher octane gas it kind of defeats the economy purpose of the idea.

lou_dias:

please quanitfy "runs much stronger" ?!

what is your 0 to 60 time?
1/4 mile?
is the engine stock?

the engine does not open the egr valve when you are leaning on the gas pedal. So blocking it off wont make any difference when it counts.

maybe you had an egr that was stuck open, so bypassing it improved your engines performance from defective to altered.

but unless you are running high octane gas now (which is not required for a fiero with a proper egr setup) your engine is gonna ping when you let off the throttle - not a good thing.

quote Originally posted by Ken Wittlief: but unless you are running high octane gas now (which is not required for a fiero with a proper egr setup) your engine is gonna ping when you let off the throttle - not a good thing.

I have NEVER heard of an engine pinging when you let off the throttle. Please elaborate.

the egr valve is opened when you let off the throttle - then it lets some of the exhaust gas back into the intake and reburns it.

The ECM is programmed to compenstate for the change in mixture - so when it opens the egr it advances the timing. If they didnt advance the timing at this point then the air/fuel mixture would not burn completely.

if the egr is there and is working properly - everything is ok. if its blocked off, and the exhaust gas is not going into the intake, then you get pre-ignition and the engine pings and sputters.

I use to block the egr on my VWs years ago, then when you let off the gas to slow down the engine would pop and sputter - I thought it sounded cool. But with a fiero its worse cause the ECM moves the timing too.

thats why you would have to run high-test with the egr blocked - to compensate for the advanced timeing - and you still would not have any more HP when you tromp down on the gas pedal - so whats the point?

you wont hear it as well as you hear pinging when the timing is set wrong and you are really winding the engine out, or going up a hill - but the pre-ignition will still be happening.

some people that have done it temporarilly while they were waiting for a replacement egr to come in, have noticed when you let off the gas and are crusing at a steady speed - it feels like the engine is surgeing - thats the ECM advancing the timing - expecting the gas to flow, and it doesnt - and the ratios are all wrong.

[This message has been edited by Ken Wittlief (edited 06-22-2001).]

Here we go again... Hopefully nobody calls the EPA this time.

Here's a link to an article that explains what Ken is talking about in detail. It's focused primarily on the V6 where the EGR is ECM controlled. Although the L4 ECM does not control the EGR directly, I would think the fuel/timing curves are setup assuming it is operating.
http://www.mindspring.com/~fierosketch/osg/EGR.html

Thanks for all the help. After reading here is some more info that maybe I am doing wrong. First the engine has a header (hooker) on it with open exhaust, only a resinator tip, (i am fixing this because it is way to loud), second, I only run 93 octane in it. Is that wrong, I think it runs better on 93 over the 89 I was running in it. I have an open element air cleaner and other than that it is stock. So...it is running 93 a bad idea, is the open exhaust hurting anything, and I guess the answer to the EGR is leave it alone.

Thanks

Rob

------------------
qwikgta@yahoo.com
88 T-Top coupe, 65K, Header no Cat, 16" GTZ rims, short shifter, swaybar, open element air cleaner, hood vents.
http://robsfieroproject.homestead.com/index.html
http://vafiero.com

you only need to run 93 if you have high compression pistons or a turbo. Otherwise regular unleaded will actually give you more HP. If you have stock pistons and your car pings then check your base timing - if its advanced then the car will ping, and 93 will make it stop pinging, but that timing being a little off is costing you, what? $2 or $3 each time you tank up?

the only reson to put 93 in is if 90 pings, the only reason to put 90 in is if 88 pings...

check your timing and try the cheaper fuel. The guy at the gas station is laughing at you each time you tank up with 93.