What would the effects of removing the EGR do besides throwing a code ??

rough idle.. poor gas mileage... slight loss of power...

you can just remove it.. you need to also disable it in the computer, otherwise the computer is trying to adjust and compensate for it..

Jeeze. Some loss in power. I was always under the impression that it was a power robber. I mean say you re-programmed the ECM and you blocked off the passage with a plate. Would you still have loss in power and rough idle. Worse mpgs I understand though.

you will have those symptoms only if you do NOT take it out of the computer..

and no you're not going to see any difference in HP or TQ by deleting the EGR.. all it does is take a little bit of burned exhaust and add it to the new air to help get a better mixture.. which is always a good idea..

on a side note.. if you are deleting the EGR and air pump.. you might as well take out the CAT.. you're not going to need it and you'll problably get some HP

so if you were looking to ditch the system for purely to gain HP.. dont waste your time unless you delete the entire system..., such as block the air tubes.. remove the cat, air pump, EGR tubes.. ect.. not worth the time if you ask me..

Thanks for your help. I'am already going to remove the CAT and eventually the AIR system along with the tubes. Mostly because the AIR system takes up too much space in the engine bay and it clutters all the working area.

See this thread on EGR and it's affect on mileage.

wow , thats really interesting. I had no idea that the ECM would increase timing to compensate for the slower burn when the EGR was in use. I guess Ill just leave it on there. Oh one thing just so I dont get confused the AIR system that has those tubes next to my manifolds thats not part of the EGR is it??

those air tubes go to the cat to help heat it up and make it function a little better when the car is cold

Alright cool man. Thats what I heard but I just wanted to make sure before I eff my engine up. Thanks for all your help.

well, if you switch to a HSR with no EGR waht happens,...if it was needed wouldn't they have a provision for it?

Holley expects that you'll actually have the car tuned after installing the HSR that way it'll function properly. Not every one does, but should...

You should see how clean my intake and valves stay without that thing in place.

Its not all gain and no loss, nothing is.

Exactly, hot dirty air being recycled into my incoming air is a bad idea. Cool,dense air makes more power, period. It is there for emissions only. Get rid of it and reprogram your prom to keep the light off.

removing EGR = stronger idle.. better gas mileage... slight gain of power...

there I worded that one correctly.

better gas mileage?

anytime you remove somthing from your serpentine system that si not neccisary you are going to see a slight increase in efficiancy. it may be more due to the removal of parasitic loss of the pump then anything to do with the EGRs effects on the way the engine runs. i don't know for sure. if done corectly deleting AIR/EGR from these older models will only hurt your emissions (not always, just in general)

we V6 guys are lucky on the EGR/AIR. our air system ceces to function at all once the engine is warm.

I'm in the process of installing headers so I've been researching removing the AIR and EGR systems. Like others have said, I dont think it will make a difference as far as more power or less weight, those things will be minimal if anything at all. The main advantage will be more space in the engine bay to work, things become more accessable. And to be honest I think this only applies to the AIR system, the EGR system does not get in anyones way. If I understand the AIR and EGR systems correctly they do not work together. The EGR system consists of a solenoid located under the Ignition Coil and a valve locate under the Intake Plennum between the fuel rails, both vaccum opperated. Removing this does not really offer you any extra engine bay room, I would say just leave it. The AIR system on the other hand has alot of components that do take up quite a bit of engine bay space, there is a belt driven pump connected to the serpentine belt system, multiple valves, and alot of tubing. All those tubes on the top of the exhaust manifolds (which connect to the CAT in the exhaust) as well as that black plastic box that sits behind the A/C compressor on top of the valve cover on the pass side, thats all the AIR system. I think removing that system is worthwhile and will give you more engine bay room. From what I've read it will not cause a SES code, but be aware that the ECM does take into account the AIR system and this may cause problems (but may not). Once the AIR system is gone you no longer need the pump, so you could either install the delete pully or I've read of others gutting out the stock pump and the pully just spins freely like a delete pully (but I've never done this, no idea how). For my setup I'm installing headers with no AIR tubes, the AIR pump delete pulley, and I'm removing the cat. But the EGR will stay in place and hopefully I will not get any SES codes or side effects.

For those that believe removing the EGR will improve power in WOT, they are completely mistaken. The ECM disables the EGR in WOT - so removing it to improve power has no effect.

In part throttle, many people have found their car runs better with the EGR disabled. But, this is probably because the EGR is not working properly or the plumbing is all carboned up. With proper tuning, a fully functioning EGR can help get some great gas mileage. When my L98 was stock, by just tuning the eprom inconjunction with the EGR, I got 30 mpg (US not Imperial).

But if you are modifying your engine, most guys remove both the EGR and AIR systems if they don't have emissions testing to worry about. It does remove some of the clutter and makes the engine a little easier to work on.

Even though it makes a mess, just make sure it isn't glogged up and leave it alone.

Stock 350 with 4l60 and the lowest numerically gears available stock were 2.73 won't even sniff 30 mpg with a tail wind, downhill
driving 40 mph. I have had three of these and if you get 22 you have done great.

'88 GTA, 350, 700R4, 3.27 BW rear.

I get worried when it drops UNDER 25 mpg in my travels which are on mostly hilly curvey backroads.

Many times I've seen 28-30 mpg. A handful of times over 30 mpg when driving at speed limit (55 mph).

A couple years ago, filled it up, drove it to the drag strip (60 miles one way), ran it about half-dozen runs (14.0s at 99 mph), came home and re-filled and still averaged 18.5 mpg.

I do have headers, and the other small free mods (dynoed 224 at the wheels).

TPI cars were FACTORY rated at 24-26 mpg highway.

jms

I would have to say you divided wrong. No way a stock TPI car gets that kind of mileage. People like to exagerate. LS1 with a 6 speed might have been rated at close to 30 highway, not a 4 speed auto 10 years previous. For example a 95 s10 with a v-6
rated at 18-24 city/hwy. No matter how easy you are on it it stills gets about 21. Very normal for these vehicles, as is 20-21 for our 50-5-7 TPA with auto and highway gears. You guys have a odometer problem or you figured wrong. Three mid eighties TPI autos and another midsize v8 5.0 auto with highway gears proves you wrong. I could see 24 at the absolute most with a tail wind and 100% highway miles.

Nope, no Before I modified my engine, I got 30 US mpgs on the highway. Remember, this is AFTER I modified the eprom for highway mode (and I'm rather good at it ). With the original eprom, 23-24 US mpgs would be the absolute best I could get. And that's only if I really babied the engine and never drove faster than 55 mph.

As a test, I re-burned an eprom for another buddy with exactly the same parameters as I used. He had the same car as mine (91-92 SD L98, 4L60) and he experienced the same kind of mileage. Also, his et's improved about .4 secs. He could have gotten .5 secs better but he could not get 94 octane where he lived The best he can get was 92 octane, so I had to pull some spark timing out so the engine would ping.

But he experienced almost the same gas mileage on the highway. I think he got the equivalent of 29 US mpgs.

Again, for people that don't read the threads in this post, and it's relevant because what's being described below for the 94-96 Impala SS is also a scheme used on the 3rdgen cars.

From Car Craft mag August 2004, "Whats Your Problem" help column:

Originally posted by Jetmeck
"I would have to say you divided wrong. "

Nope, been figuring my fuel mileage since the early 1970s.

Fill Tank. Drive x amount of miles. Refill tank. Divide x amount of miles driven by number of gallons used (including fractional amounts). = MPG

"No way a stock TPI car gets that kind of mileage."

Mine isn't totally stock but I have seen stock TPI cars get better than you claim.

"People like to exagerate."

Nope. I'm 49 years old and don't have to prove a thing to you.

"LS1 with a 6 speed might have been rated at close to 30 highway, not a 4 speed auto 10 years previous."

Search this site for factory window sticker pictures showing city/highway mileage figures for TPI cars.

"For example a 95 s10 with a v-6
rated at 18-24 city/hwy. No matter how easy you are on it it stills gets about 21."

No matter how easy YOU are on it. Not every one drives the same.

"Very normal for these vehicles, as is 20-21 for our 50-5-7 TPA with auto and highway gears."

For YOUR vehicles.

"You guys have a odometer problem or you figured wrong."

Nope. Checked my distance driven on the same routes against several other vehicles and they come within a small fraction of being the same. Some over, some under.

"Three mid eighties TPI autos and another midsize v8 5.0 auto with highway gears proves you wrong."

That just proves you couldn't do it. Could be the vehicles had something as simple as low air pressure in one or more tires or front-end alignment off a fraction or one plug wire not 100% or any of dozens of other factors.

Or maybe we don't all drive the same.

I've taken my GTA over 140 mph. But I don't push it all the time. I don't sit back in it and let lines of traffic build up behind me, either. I don't run right up to a known stop sign or light and slam my brakes. I don't show the world how easy it is to absolutely obliterate (smoke) my tires from a stop (well once or twice, lol). I don't tailgate and have to constantly hit my brakes.

"I could see 24 at the absolute most with a tail wind and 100% highway miles."

Fellow thirdgen entusiast---With no attitude meant toward you, and hoping you take this in the best possible way,: Something was wrong with your vehicle(s) (or the way it was driven) if it couldn't (never) get better than that.

Search this site for "What kind of mileage do you get" type of threads. Sure, you'll see TPI cars having trouble getting decent mileage. Many times though, those same posters will be starting other threads like "What's wrong with my car?"

You will also find MY range of mileage is not all that uncommon.

However, to come on to a site and call similar claims made by others untrue just isn't cool.

Everyone is different. Every car is different.

Every opinion is different.

You just got mine.

jms

i'm not worried or concerned with power and gas mileage or whatnot when u remove EGR and AIR

its a neccessity for those swaping to HSR.. as it has no provisions for EGR.
whats all involved with turning it off in the ecm? is it just a flag where i can simply just select off?

well actully the egr valve induces air from ur exhaust into ur combustion chambers on decell and i beleive part throttle only it keeps cylinder temps down by taking up volume in the c.c if u have aftermarket headers on ur car ur egr is useless because the port where u get the exhaust gas from is now blocked removing it will only run ur cylinder temps a lil high give u no performance in wot only part throttle acceleration it will also put more Nox in ur exhause gasses so u wont pass emissions

all this about a simple EGR valve?

on a properly working EGR system, the only time the EGR will be in operation is under cruise & light acceleration, period.
with a properly working EGR system you will never know its there, it will not change how the car idles, it will not change power output at full throttle. it is there for NOx reduction.

there is debate over if it does increase fuel mileage or not, i did gain some mileage increase with EGR, but i am a little more aggressive with highway mode with EGR than with out it.

headers on a thirdgens doesn't change where the EGR valve gets its exhaust gas from, headers can have an effect on the the EGR valve if its a positive or a negative back pressure valve.

i am at just over 25 MPG highway on my monte carlo that has a 5.7 TPI from a 92 camaro, a car thats more like a brick going down the highway than any thirdgen, & i know there is more in it. so i have no problem believing a much more aerodynamic thirdgen hitting 30+ MPG.
if your not getting 25+ highway with a mostly stock thirdgen, get into chip burning, find your problems & fix them.


*edit*

Orr89RocZ, find the temperature settings for the EGR stuff & the diagnostic speed & turn them all up to max, next find the EGR duty cycle settings & set them to 0, i don't remember if you will still need to uncheck the code 32 flag or not to keep the engine light off.
there are probably some other ways to turn it off, but this is how i had mine turned off.

a search through the prom burning board should turn up anything else you need.

Sorry,

I would have to agree with JETMECK,


I have owned my car for 15yrs and never have gotten over 17MPG,


and now , modified with tuning , am only getting 14mpg. I and my BLMs are in the 128-130 range. I know there could be something else;

-purge solenoid,

- I have a relatively new GM egr, and solenoid

- my CA gas is mixed with too much ethanol?

anyhow , 25- 30 mpg from a 5.7 with an 700R and 3.23 gears sounds like a stretch, I have an LS1 with a 6sd and these cars do not get 30mpg either , and they only get those high #'s when driven mainly highway( like 90%) if you drive mixed, or sit in traffic for long periods of time you will be lucky to get 18-20mpg, you drive 80% city and you will get 16-17mpg with a LS1

It is hard for me to believe a L98 can get even 25mpg - your saying that an L98 will get 400mi to a tank of gas- I don't think so...

My 93 Roadmaster wagon, 5.7 LO5 TBI with 3.23, gets 23+ mpg on long highway trips. My 93 Caprice sedan, 5.0 LO3 TBI with 2.56, has recorded over 26 mpg last summer on two separate tanks of fuel and two different trips. My old 94 LT1 9C1 copcar with 3.08 went 22.7 mpg on a trip to Maine and back, and that trip included some around-town driving. All three cars had/have 4L60/4L60E. The sedan and wagon both approached the EPA highway mileage rating; the copcar was shy by 2-3 mpg.

Around-town mileage is (or was) obviously less. The wagon and the copcar managed18 mpg, the sedan 20-21 mpg respectively.

A 3rdgen Fcar that weighs 600+ lbs less than each of the three cars above and has a lower frontal area and smaller C_d should be able to do as well, or better than my cars. But you have to drive with an easy right foot and the EGR system has to function properly to gain the lean cruise.

My Super LO3 van was getting 23 MPG at 70-75 MPH with the A/C on and all open highway. That is with 3.08s, a 700r4, and factory L69 Van cam. That is 3 MPG better than the 1983 G20 4 spd carbed 305 ratings on the highway. You have to consider I have electric fans and lots of chip work on a TBI system.

My latest combination with 3.73 gears and 275+ RWHP still gets 18.5 on the last highway trip. It ran a 15.5 @ 88.7 w/ 2.4 60' time and weighs 5,300 lbs.

I use EGR, it is worth almost 2 mpg on steady state cruising (With the Proper A/F ratio and added timing). Turning the EGR off results in a 2 mpg loss on two different engines in the same truck.

My dads 400+/- hp TPI'd L98 3.42 200-4R GP just averaged 21mpg on a trip a few weeks ago, averaging 70MPH (including stops) and mostly driving 90MPH, with 3 passengers and a trunkful of stuff. That car is also untuned since some major changes, although the A/F is around stoich at cruise. It previously had a hard time getting more than 20, with a lower output combo that obviously (to me) was not as well matched. My 100% stock 89 GTA L98 3.27 vert gets about 22-23, but it needs a tuneup or something because it has a slight miss. I think it'd do better if it ran just right. My 86TA LB9 3.27 sucks the tank dry like its cool, wont even go there. 85TA I had (LB9, 2.77 rear) would usually get 25-26 although on one trip I drove fuel mileage minded and almost hit 30. That car was also 100% stock.

I dont see 25+MPG out of a 3.23/3.27 L98 car as impossible or out of the ordinary, some cars just dont run right. Take my 86 as an example, I used to get 23-24 highway and then one day something happened and now the mileage is crap. Everything checks fine and most everything has been replaced but boy does it like to eat gas.

Its not just the motor either, people need to consider alignment, tire pressure, wheel balance, passengers, baggage, engine load from alt, ac, all kinds of things. Drive a TA at night (lights on!) and watch your fuel mileage drop

When I had my 2.73's, and no mods except for a k&n, I got 28-30 mpg(our canadian gallon is 4.54 Litres)

With my mods now, with 19lb injectors, I got 28mpg

With 24 lb injectors, I get 26 mpg.

No bs, have had my car since dec/97, and almost every tank I calculate mileage!!

What folks seem to be missing is: Highway Mode. He stated that he has done some prom tuning (a lot of prom tuning?) This has a MAJOR effect on fuel economy, especially if he does a fair amount of driving that takes advantage of Highway Mode.

Lots of good talk on this subject, I believe in the 20-25 mpg@ on the L98 cars as I have seen on average, based on mild driving habits, with minimal mods, My question is I am looking at removing the smog pump or gutting it on my 87LB9 5speed Iroc, I have the upgraded serp/setup and the SLP 1 3/4 headers, N10 dual cat setup and powerflo 3"exhaust, just want to know if I will receive any codes due to the removal of the smog stuff, as I do not get tested any way, the other option is to go with the shorter belt/rerouting method.......I am a believer of the EGR valve, (when it works, and is maintained properly). this system is no way like the early 70's cars ever were, I can vouch for that.

Perfectly tuned prom wise with and without EGR will be about the same.

Tuning can make big gains for feel, power and driveability and help in the mileage department

I dont run it on my 2 fun cars, but it is intact and operable at this point on the GTA, just due to the fact I havent completely changed everything I have wanted to codewise yet.

A stock TPI 350 car should net 22-25mpg straigh highway. I could do this in my Form or my GTA when both were purely stock. One had 17k on it when i got it, the other had 41k on it. GTA pushed a little over 25+ driving it home from Salt Lake City to IN. Formula clipped 24+ a few times on other long trips like vacations and the such where it was 99% highway.

My current 383 in the Formula is running no emissions garbage(other than when I actually take the test) and has a mild 216/221 cam, low compression(boost in future)and 30# injectors with a full headers/catback exhaust. It uses a vortec heads and base with hogged out SLP runners and plenum.

Thru tuning and no crazy tricks or even using highway mode I was right at 22.5mpg highway with a loaded car on a 6 hour trip. Would be better now, but I'm lacking funds and car isnt cooperating with me.

So what is being said is true, its not that hard to believe, look at the stock TBI cars with highway mode form the factory, they get upper 20's even 30mpg on the highway, the TPI 305 with the highway gears do to.

later
Jeremy

All I have to say is any of you claiming 25-30 mpg range out of 305/350 7r4 best talk to fourth gen guys with six speeds. Most of them don't even get that and yet we are to believe you can do it with two less gears. NOT

lol

Hey, believe what u want :-)

We know what we have done, seen observed and tested on ours and others vehicles.

By the way, when I had my 97 30th Z w/ a 6spd, I could do high 20's-30mpg on the highway. Routinely avg'ed 23-25 with half and half city/highway. Thought it did pretty good.

My friend who bought it from me has hit 29 to almost 32mpg in it, loaded with 3 people and stuff for a week long trip that was 6+ hrs each way.

We both verified it by checking for mileage vs odo at every fillup.

later
Jeremy

long time viewer, first time poster, I felt that I must my 2cents to this one, last july my wife and I vacationed from south dakota thru wyoming, montana, (including yellowstone park), and colorado, in our 91 z28 w/5.7-th7oor4-3.23 combination and newly installed edelbrock ceramic coated t.e.s. headers and dynomax after-cat exhaust system on an otherwise stock engine with 135000+ miles on the clock and averaged 25 m.p.g. in a 2500+ mile trip. thanks randy

Yes you can remove it without any codes. You will need to get a different size belt and routing is a little different. I heard you can buy a delete pulley also but not sure.

Thought I would add that I get 13 in town when racing or driving hard. 18 is the best I get in town when driving to work and back and nothing else. On the Highway the best is 26 and worst is 20(alot of acceleration and slowing up) That is all on my 88 slighty modified.
I also have a stock 97 TA that I get a best of 19 driving to work and a best of 28 on the trips to Fort Worth. On some of the faster trips I get 24.

EDIT: the belt and pulley was for the smog pump was it not johnny? EGR is not belt driven or am i backwards again?

Right I was answering this----v The EGR is on top of the intake between the fuel rails

ohh ...i didnt read the whole thread, just the last few parts you sent me

I have another question about the air pump, If I remove the air pump and use the alternate method of re-routing the v belt, do the dual cats (n-10) need air from the pump, or can that line be welded shut at the cats, without gutting them, the other smog lines I can cap at the headers.

Any updates?