EGR limiter

Post by **HenryJ** » Sun Dec 22, 2002 8:05 pm

For those who have done the throttle blade restrictor removal or installed the CFM replacement.

Sonoma 96 is offering a "Sale" on his restrictor fittings-$20 delivered!

I'm sending my payment in the morning.

Here's the thread on ZR2.com

I already have a different one at the exhaust manifold, but at this price I'm going to try his.

a2b · Post by **a2b** » Sun Dec 22, 2002 8:36 pm

didnt you already cut yours off?

either way, let me know how the peformance gain is.

Post by **HenryJ** » Sun Dec 22, 2002 8:52 pm

Yea I have a limiter in down low. You can't cut it off, it sets the SES everytime!

I'm doing it to reduce the carbon deposits, I don't expect much of of a performance gain.

The main reason would be so you don't lean out the forward cylinders after removal of the throttle blade diffuser, due to uneven mixing of EGR gasses.

a2b · Post by **a2b** » Mon Dec 23, 2002 10:03 am

yeah, thats why i dont do much performance mods....the power is fine for me...its still a v-6 so i dont expect much...i wish an engine swap was easy..that would fun as hell

Post by **HenryJ** » Mon Dec 30, 2002 1:50 pm

It arrived today!

And looks real good

There is more than $20 worth of machine work into this fitting IMO.

It was nicely packed included instructions and arrived promptly.

I got the steel one , since I had concerns with the strength of the aluminum threads. So a coat of paint , get my friends truck put back together, and out of the garage and I'll install it.

Steven · Post by **Steven** » Mon Dec 30, 2002 2:43 pm

is it really worth it?. I mean do you really see deposits? I run my truck... not easy on the throttle....I dont have much "in-town" driving....

I was under the impression that the issue only comes into play when you do alot of intown driving... stop and go stuff.

Would it still be worth it?

Post by **HenryJ** » Mon Dec 30, 2002 3:21 pm

Steven wrote:is it really worth it?. I mean do you really see deposits? I run my truck... not easy on the throttle....I dont have much "in-town" driving....

I was under the impression that the issue only comes into play when you do alot of intown driving... stop and go stuff.

Would it still be worth it?

One word...ABSOLUTELY!

(more words

)

The EGR valve opens to test itself at speeds above 10 mph , no acel. or decel., blah blah... and during normal driving I'm not positive of all the conditions.

Open your throttle blade and you'll see all the carbon build up even after only 5000 mi.

I've seen several that have never been cleaned and at 60K it is unbelievable!

For those who removed the throttle blade diffuser it is extremely important to limit the EGR gasses that are introduced, in order to prevent leaning the front cylinders do to uneven mixing of the gasses. (that's what the diffuser was on there for)

I added the lower restrictor and feel that this one is definately worth a try . This guy has done the research, and should know what he is doing.

I'd dearly love to eliminate the darn EGR system , but haven't figured out how to fool the PCM yet.

Conman · Post by **Conman** » Mon Dec 30, 2002 3:28 pm

Since the 2002s don't have the EGR(or does not use it anymore), does it still have the carbon build-up problem? If so, what's the best way to keep it to a minimum and what kind of clean is recommended?

Thanks,

Con

Post by **HenryJ** » Mon Dec 30, 2002 3:47 pm

I'm kind of an idiot when it comes to the 2002-up EGR system. I've heard it is still there , but just relocated. So I can't be of any help on limiting it. Maybe they didn't 70% over engineer it like they did on the 2001's.

I'd say wipe the throttle body out and the back side of the throttle blade, with a carb. cleaner soaked rag at every oil change. And add some injector cleaner fuel treatment every 5000 mi.

Those are things I do too.

Post by **HenryJ** » Mon Dec 30, 2002 4:43 pm

Steven , I just though of this. Since you are going Forced Induction, what do they do with your EGR valve now that the intake manifold will be under pressure, rather than vaccum?

Seems like under boost it would not work the same , or maybe it doesn't develop enough boost to affect it?

So many questions, so few answers.

You may be blowing air into the exhaust due to the pressure in the intake manifold

or at least sacrificing boost.

Steven · Post by **Steven** » Tue Dec 31, 2002 7:56 am

I know that on the 2001's theres an air induction tube that enters the exhaust manifold. Is that what your talking about, and I just dont know how they handle the boost verse vacuum. Not sure, but after talking to others, it works.

I've been talking to my wife lately about the S/C... and now I'm wondering if I'm just being foolish,... Should I just go buy a V8 and be done with it, or will the engine take the extra horse power. Of Coarse Powerdyne says it will... and actually they claim that it's easier on the motor cause it produces more power at lower RPM's... so less wear and tear on the motor.

Post by **HenryJ** » Tue Dec 31, 2002 8:51 am

Steven wrote:I know that on the 2001's theres an air induction tube that enters the exhaust manifold. Is that what your talking about

Yes , thats the line I'm limiting.

I've been talking to my wife lately about the S/C... and now I'm wondering if I'm just being foolish,... Should I just go buy a V8 and be done with it, or will the engine take the extra horse power.

I personally don't know how much boost this system is designed to develop. I would say that anything around 5-7 psi boost max. would not be a problem (other than having to run the best premium fuel you can find) . Turbos develop that much.

Then again I don't know the properties of this engine, ie. piston composition and compression ratio, crankshaft material ,rod design , camshaft profile, head gasket design, etc.

A S/C is hard on the bottom end and develops lots of heat.

I think I will go with a V-8 at some time in the way distant future, if I don't decide to go with a really built V6 (ZZ4.3?)

There is still lots of room for improvement with the V6 we have.

How about just going with a good set of headers for now? You will need them if you decide to go with the blower anyway.

Post by **HenryJ** » Sun Jan 05, 2003 3:12 pm

I've had "Sonoma 96's EGR limiter in for almost a week and it set the SES light today. Code PO401 insuffecient EGR flow.

Time to drill it to 3/16"!

The PCM on the 2001 is too sensitive

I figured this might occur, but He said that it will not set the code if drilled oversize

We'll see.

Post by **HenryJ** » Sat Jan 18, 2003 12:59 pm

It still set the SES light after drilling out to 3/16".

I tried it twice to make sure , now I'm going to try drilling it out to 7/32"

It is still a good idea , but it may have to be drilled out more than most would need to work for the 2001's

I'll figure how far soon, I hope

Post by **HenryJ** » Sun Jan 26, 2003 3:16 pm

The SES light is on again.

I guess that 7/32" won't work for me either

Time to drill it out further

Post by **HenryJ** » Sun Oct 09, 2005 8:09 am

This had been working drilled out to 9/32" for the last few years, but may have been really close to the "edge".
I do also have the *poor man's restrictor in the lower fitting. It had been drilled to 1/8" all this time, but the last couple weeks I set the MIL again.
I pulled it today and drilled it out to 7/32".

Hind sight being 20/20 I would say 9/32" for the upper restrictor, and 7/32" for the lower.

*Poor man's EGR restrictor: Remove the threaded EGR tube adapter in the lower left hand exhaust manifold. Thread bottom inside with pipe tap. Insert and tighten steel recessed allen head pipe plug. drill hole through plug.

Post by **HenryJ** » Sat Nov 25, 2006 12:17 pm

Update:
I have had no further problems with this mod. It really is doing an outstanding job of reducing the intake deposits.
As I understand it any gains would be in the 25% or less throttle. I can't say I have seen anything substantial.

Well worth it for the reduction in deposits though

killian96ss · Post by **killian96ss** » Sat Nov 25, 2006 12:33 pm

HenryJ wrote:Update:
I have had no further problems with this mod. It really is doing an outstanding job of reducing the intake deposits.
As I understand it any gains would be in the 25% or less throttle. I can't say I have seen anything substantial.

Well worth it for the reduction in deposits though

My EGR limiter is doing well also, and I completely agree with everything you just said.

Steve

04crewvt · Post by **04crewvt** » Sat Nov 25, 2006 1:29 pm

EGR what EGR. Those of us with 2004's don't even have them. Gm finally figured out they weren't doing anything for pollution,economy or engine life and did away with them completely in the last version of the 4.3l

F9K9 · Post by **F9K9** » Sat Nov 25, 2006 1:42 pm

04crewvt wrote:EGR what EGR. Those of us with 2004's don't even have them. Gm finally figured out they weren't doing anything for pollution,economy or engine life and did away with them completely in the last version of the 4.3l

I wouldn't be quick to say the "last" version

Check out the base engine on the "base" model full size pickups

04crewvt · Post by **04crewvt** » Sat Nov 25, 2006 1:49 pm

By G_d your right they have resurrected the 4.3 from the boneyard to underpower the 2007 WT 1500 silverado. Guess they figured it would be a hard sell to put the I5 in a full size truck.

Looking at the specs. it would boggle the mind as to why you would choose the 4.3 over the 4.8 v8. 100 horsepower less 45lb-ft of torque less at a gas cost of apx. 1mpg

20Blazer00 · Post by **20Blazer00** » Mon Nov 27, 2006 11:48 am

04crewvt wrote:By G_d your right they have resurrected the 4.3 from the boneyard to underpower the 2007 WT 1500 silverado. Guess they figured it would be a hard sell to put the I5 in a full size truck.

Looking at the specs. it would boggle the mind as to why you would choose the 4.3 over the 4.8 v8. 100 horsepower less 45lb-ft of torque less at a gas cost of apx. 1mpg

Maybe GM will get smart and either put the new 4.3 into the Colorado/Canyon or drop in the 4.2L I6

GeorgesBlazah · Post by **GeorgesBlazah** » Mon Nov 27, 2006 1:48 pm

Holy old thread Batman!

BTW is he still selling these?

Post by **HenryJ** » Mon Nov 27, 2006 4:38 pm

GeorgesBlazah wrote:...is he still selling these?

Check S-10Planet.com

I think they may have been resurrected.

20Blazer00 · Post by **20Blazer00** » Thu Nov 30, 2006 9:13 pm

GeorgesBlazah wrote:Holy old thread Batman!

BTW is he still selling these?

Why pay $40+ for something that you can make your self for a lot less and easier.

Instead of buying one of these finely machined parts a friend had figured out that if you take a 3/8 npt plug put in the 5/32 hole and thread it into the manifold you have the same thing for a lot less. The hardest part of this method is drilling the hole wider in the manifold with a drill for a 3/8 npt thread. The hole was just a hair under what was necessary for the tap to cut threads. We used a 9/16 drill in a 1/2in drill motor. We had to move some parts out of the way but it was worth it to do the mod.

Parts needed for this version are:

3/8 NPT plug from donor engine in junkyard (ie: thermostat housing?? or other intake manifold plug.

3/8 NPT drill and tap kit from Home Depot.

My suggestion is to find or make a flat washer with a hole saw of the correct diameter and drill the 5/32 hole in the middle then place it in the manifold in front of the EGR supply hose should only lose 1/2 - 3/4 thread??

Post by **HenryJ** » Fri Dec 01, 2006 5:39 am

20Blazer00 wrote:... you can make your self for a lot less and easier.

The exhaust manifold does not require drilling. It is already the right size to tap. Remove the adapter fitting, tap threads, install a recessed allen pipeplug with a 1/8" hole drilled through it. Reassemble.

The "washer" idea won't work if the piece you cut is steel. The exhaust gases deteriorate it too quickly. If you could find stainless steel of the correct diameter, it might work, but I had no luck finding the right washer.

20Blazer00 · Post by **20Blazer00** » Sun Dec 03, 2006 9:22 pm

Not the exhaust manifold, the intake manifold were the EGR tube enters the manifold just behind the A/C...

Post by **HenryJ** » Mon Dec 04, 2006 4:00 am

20Blazer00 wrote:Not the exhaust manifold...

Why?

killian96ss · Post by **killian96ss** » Mon Dec 04, 2006 12:38 pm

HenryJ wrote:
20Blazer00 wrote:Not the exhaust manifold...
Why?

The EGR limiter is designed for the intake manifold, however it doesn't really matter which end of the EGR tube that you restrict the exhaust gasses.

Steve

Post by **HenryJ** » Mon Dec 04, 2006 4:42 pm

This is getting a little confusing. I'll try to clear it up a little.

The manufactured EGR restriction fitting is designed to be mounted in the intake manifold. This limits the space between the restrictor and the valve. Less opportunity for the balloon effect to be an issue.

Adding a drilled pipe plug to the exhaust manifold requires only removal of the line and adapter, then tap pipe threads for installation of a drilled recessed allen head pipe plug. Easy install.

I have both.

20Blazer00 · Post by **20Blazer00** » Mon Dec 04, 2006 9:13 pm

Here is the install link from s-10planet.com:

http://www.s10planet.com/forum/showthread.php?t=5165

It will show you the $40 item and the location it installs into...what a friend found out was that there is a step in the mounting location that is ready to be drilled out for a 3/8NPT thread which is the same size as socket/allen head plugs found in the block or cast iron intakes on GM cars/trucks. You have to move the A/C compressor out of the way and try to get a 1/2" drill motor with a 9/16 drill bit (drill size for the 3/8NPT tap. So he drilled a 5/32 hole in the plug and then threaded the intake and it was hidden and worked.

It will take a little time since the drill bit size is not much larger than the factory egr passage size, so the drill will hang occasionally. We used a shop vac to suck out any filings then checked the fit of the plug. We decided that it should be either flush or slightly lower than the step it is in, so that when the EGR pipe is reinstalled it looks factory, no hint of mod if the dealer has to look at it.....

Snoman002 · Post by **Snoman002** » Tue Dec 05, 2006 4:08 pm

Does anybody who removed the EGR valve notice a relief cast into the valve or the intake where the pintle goes?

New EGR's for the old 4.3's (TBI's at least) come with a bag full of washers with different size holes in the center to limit exhaust gasses. If there is the relief for the washer on the valve or the intake in the new 4.3's the same thing could be done. With that it's completly invisable and does not require any taps or anything, just a washer (of the proper material).

I'm not sure what material the washers were made out of that came with the EGR's for the older trucks, but since each EGR came with a bag of 10 different sizes I'm sure it wasn't anything fancy.

20Blazer00 · Post by **20Blazer00** » Tue Dec 05, 2006 9:14 pm

Newer 4.3L use a Linear EGR Valve so it will vary the amount of gases based on computer progam. But you can still limit the amount that gets to the EGR valve to use by restriction in the feed system...

Snoman002 · Post by **Snoman002** » Wed Dec 06, 2006 7:31 am

20Blazer00 wrote:Newer 4.3L use a Linear EGR Valve so it will vary the amount of gases based on computer progam. But you can still limit the amount that gets to the EGR valve to use by restriction in the feed system...

Yes, I understand that. But limiting the amount of gasses that gets to the valve, or the amout of gasses that come out of the valve results in the same thing.

My point was that instead of tapping the manifold, or buying a $40 adapter, you could get the same results they same way they limited the gasses on the old systems, IF the valve or intake manifold has the relief in it.

Post by **HenryJ** » Wed Dec 06, 2006 7:46 am

I think you guys are referring to adding a plate or restriction at the valve.
This does not work for 2001.
I do know that it does work for 1996 models.
The 2001 PCM is pretty tight. I tried the plate first. Cut a plate to match the gasket. match the hole size for the side that the valve pintle resides. This prevents the pintle from being held open should it extend slightly beyond the seating surface, and prevents problems with inadequate flow from its interference. On the other side drill a 1/8" hole for gasses to pass. This works great for the earlier models. Buy a couple gaskets and sandwich the plate. Really easy.
It does not work for 2001 though. I kept increasing the size of the hole and kept getting insufficient flow codes up to 1/4" or larger holes. It must be something about the turbulence and speed in which the pressure change takes place. Restriction farther from the valve seems to work much better.

Snoman002 · Post by **Snoman002** » Wed Dec 06, 2006 9:04 am

Hmmm, interesting.

I bet it has something to do with the fact that the farther the restriction is from the EGR the more gas that will be sent out when the EGR initially opens. Granted as the valve remains open the flow will be restricted, but when it initially opens a farily large volume of exhaust gas behind the valve will be there to initially shoot into the engine.

Post by **HenryJ** » Wed Dec 06, 2006 9:21 am

That may be referred to as the "balloon effect"
Personally I think it has more to due with the fact that with the restriction between the valve and manifold there is not a sufficient pressure drop as the valve opens. The PCM monitors the pintle position and barometric pressure. When the valve opens a drop in pressure is measured. If this drop does not meet the preprogrammed criteria a code for insufficient flow is set.

The 2001 PCM is set pretty tight. This is not the only parameter that has very little cushion.

Snoman002 · Post by **Snoman002** » Wed Dec 06, 2006 10:32 am

I guess that PCM is really tight, heck with the EGR restricted upstream the pressure drop when the valve opens would be VERY little.

This is all very interesting.

HJ, do you have a write up on your restriction in the exhaust manifold? You have described it very well and I'm sure I could do it on what you have described but if you have a write up that would be nice to look at. Our Bravada suffers from the carbon build up and I have been looking for a way to help. Plus I wouldn't mind taking the crescent off the throttle blade for a little better throttle resonse.

Post by **HenryJ** » Wed Dec 06, 2006 11:10 am

Snoman002 wrote:...do you have a write up on your restriction in the exhaust manifold?

I do not. It is one of those things I did soon after acquiring this truck. I was unsure as to whether it would work and did not document it. I would take it out and shoot some pictures, but it has been too long without antisieze and the nut has seized to the adapter.

This was a long time ago, so details are a little foggy. Access to the EGR tube and the exhaust manifold can be made through the left hand (driverside) inner fender well skirt.
Checking the shop, it looks like I probably used a 1/4" pipe thread tap. Take the stainless steel flex pipe off of the manifold adapter and remove the adapter from the exhaust manifold.
The bottom side of this adapter is just about right to gently tap threads inside the bottom (manifold) side. The threads will not go full depth, but plenty to retain the pipe plug. Insert the recessed allen head pipe plug and snug it up. Once installed you can place the adapter in a vice and drill a 7/32" hole through the pipe plug. I say 7/32" now since upon rereading this thread, it looks like the 1/8" was a tiny bit too small. 1/8" may work, but will require periodic cleaning to avoid setting a code. The recessed side usually has an indentation inside the hex portion that makes centering the bit for drilling pretty easy.
Deburr the edges of the hole , if you need to and reinstall.
Some antisieze in the threads of the adapter and the tubing nut would be a good idea. This is something I wish I had done, but sadly did not.

Reversal of this mod is easy. Buy a new adapter, remove the pipe plug, or drill it out.

Miles · Post by **Miles** » Thu Apr 12, 2007 5:42 pm

Sorry to revive an old thread, but I've got a few questions. After tuning up my Blazer yesterday, I noticed a large amount of carbon buildup in the TB. While there, I noticed the UFO that was attached to the throttle blade. Curiosity go the better of me, and I started to research it.

WOW! I feel like I just woke up from the stone ages! Modification of this particular area has been around for several years now, yet I am just now seeing it. Brule, I have to say that your forum is so chock full of info, I don't even know where to start! I've been reading linked thread, after linked thread on the subject, for several hours now, and have learned quite a bit!

Very informative.

Now to my simple questions...

1.) Can these EGR intake restrictors still be purchased, and if so, where? EDIT: They can still be found HERE .

2.) Secondly, is it necessary to perform the second restrictor in the exhaust manifold, or is it's purpose merely to further the reduction of carbon buildup in the TB & intake?

That is all, and thanks in advance!

Post by **HenryJ** » Thu Apr 12, 2007 5:57 pm

Actually I installed the one in the exhaust manifold first. There were no restrictors available for the intake when I made the modification. I experimented with plates and ended up with the plug in the line adapter at the exhaust manifold as the best option at the time. I think it is a good help, but either one alone will work fine.

I think the inline restrictor in the intake is a good piece. The one in the exhaust manifold works well too. However it can only be removed a limited number of times before the threads on the adapter gall. I played with mine quite a few times and now I can not remove it without damaging the manifold.

$35 shipped to your door will pay for itself in cleaners alone if you keep your rig for the long term.

BTW, the plate style will not work. It throws a code.

20Blazer00 · Post by **20Blazer00** » Thu Apr 12, 2007 10:08 pm

Why buy. when for less than the price of the restrictor and shipping you could build your own...

I did this to my intake and it has never thrown a code. I read the thread on the size needed for the restrictor to work without throwing a code then a friend and I found that the restrictor that sells for $40 could be duplicated by finding a 3/8 NPT plug from an old engine - drilling the center I think it was 5/32" - then drilling and tapping the location where the EGR supply pipe enters the intake for the 3/8 NPT. It required all the steps to install the other restrictor. But you drill the intake with (Home Depot has drill-n-tap Kit) for 3/8 NPT, then make sure that you drill far enough into the EGR passage so that the plug mounts flush to the bottom of the threaded hole. Just to make sure that all things will seal up correctly...and the nice thing is that the dealerships can't tell that anything is even installed....

Post by **HenryJ** » Fri Apr 13, 2007 4:50 am

That is similar to what I did to the exhaust manifold adapter, but no drilling was required.

What did you do to keep the metal out of the intake passage when you drilled it and how did you recover the filings while drilling and tapping?

20Blazer00 · Post by **20Blazer00** » Fri Apr 13, 2007 4:54 pm

Used a shop vac....plus if you use tapping fluid on the tap it will keep some of the filings on the tap...

Post by **HenryJ** » Fri Apr 13, 2007 5:04 pm

The passage goes to the EGR valve, and not directly to the inake. I could see using a shop vac and some non-flammable electrical cleaner to wash out the passage afterward.
Do not use anything flammable with a shop vac. It WILL go boom!

20Blazer00 · Post by **20Blazer00** » Fri Apr 13, 2007 9:20 pm

HenryJ wrote:The passage goes to the EGR valve, and not directly to the inake. I could see using a shop vac and some non-flammable electrical cleaner to wash out the passage afterward.
Do not use anything flammable with a shop vac. It WILL go boom!

Well you are technically correct but the passage is cast as part of the intake manifold....so it can be thought of as part of the intake manifold. I have an intake from a '03 G-series 4.3 and it does not have the passage cast into it for the EGR valve but it still has the copper tube inside the upper plenum...still wondering why if the EGR is gone why the exhaust gas tube is still inside the upper plenum...

stukapilot · Post by **stukapilot** » Sat Apr 09, 2011 7:30 am

After doing the mod, I can say that I have never seen that much carbon in my life! If it's built up that bad on just the intake, I'm scared to even think about what the rest of the internals look like! I kid you not, it was built up enough to keep the blade from closing.......

Post by **HenryJ** » Sat Apr 09, 2011 7:52 am

Look into restricting the EGR, if you have one. There are several threads on the subject. That will cut the carbon build up by 70%. At least that was my experience.

A swirled cut throttle body spacer may also aid in keeping those gases stirred up too.

stukapilot · Post by **stukapilot** » Sat Apr 09, 2011 8:04 am

Well, I did the search on restricting EGR and could not find any instructions, also trying to find picture's of an airbox mod..............

Post by **HenryJ** » Sat Apr 09, 2011 3:00 pm

EGR limiter

Modified Stock Air Box and headlight support

stukapilot · Post by **stukapilot** » Sun Apr 10, 2011 8:00 am

So after doing the TB mod, I MUST also do the EGR mod because two cylinders run lean?

Post by **HenryJ** » Sun Apr 10, 2011 9:46 am

I don't believe that. I am of the belief that the throttle blade diffuser is there to dull the throttle response.

The EGR system is over engineered for sure and a reduction can be helpful. Additional modifications to aid in mixing the gases are helpful as well.

stukapilot · Post by **stukapilot** » Sun Apr 10, 2011 11:20 am

O'kay, thank you, I'll get the EGR mod and a TB spacer as soon as I can, was laid off from the sawmill so money is tight right now. (what I really mean is that my wife wont let me have any money to do fun stuff with! She says that as soon as I get back to work I can do it, but I know she is lying!!!)

Post by **HenryJ** » Sun Apr 10, 2011 11:46 am

The EGR restrictor in the exhaust manifold, can be done for under a $1 if you can borrow a tap to thread the manifold with. I would start there. That is a cheap fix that could be done on a limited budget for sure.

Do some reading on TB spacers. Some believe in one type more than another. If you're mixing gases the spiral cut may help create the turbulence better? Mine was a Helix.
The TB spacer also allows unhindered access to the thermostat and better intake alignment after a body lift. You might be able to find used TB spacers around. Check all the s-series forums.

stukapilot · Post by **stukapilot** » Wed Apr 13, 2011 9:50 am

Henry, How do I start on the EGR exhuast manifold modification? Please keep in mind that I'm retarded and need step by step instructions..................

Post by **HenryJ** » Wed Apr 13, 2011 12:00 pm

EGR restrictor thread

Hole size 7/32" for the lower.

*Poor man's EGR restrictor: Remove the threaded EGR tube adapter in the lower left hand exhaust manifold. Thread bottom inside with pipe tap. Insert and tighten steel recessed allen head pipe plug. drill hole through plug.

HenryJ wrote:
Snoman002 wrote:...do you have a write up on your restriction in the exhaust manifold?
I do not. It is one of those things I did soon after acquiring this truck. I was unsure as to whether it would work and did not document it. I would take it out and shoot some pictures, but it has been too long without antisieze and the nut has seized to the adapter.

This was a long time ago, so details are a little foggy. Access to the EGR tube and the exhaust manifold can be made through the left hand (driverside) inner fender well skirt.
Checking the shop, it looks like I probably used a 1/4" pipe thread tap. Take the stainless steel flex pipe off of the manifold adapter and remove the adapter from the exhaust manifold.
The bottom side of this adapter is just about right to gently tap threads inside the bottom (manifold) side. The threads will not go full depth, but plenty to retain the pipe plug. Insert the recessed allen head pipe plug and snug it up. Once installed you can place the adapter in a vice and drill a 7/32" hole through the pipe plug. I say 7/32" now since upon rereading this thread, it looks like the 1/8" was a tiny bit too small. 1/8" may work, but will require periodic cleaning to avoid setting a code. The recessed side usually has an indentation inside the hex portion that makes centering the bit for drilling pretty easy.
Deburr the edges of the hole , if you need to and reinstall.
Some antisieze in the threads of the adapter and the tubing nut would be a good idea. This is something I wish I had done, but sadly did not.

Reversal of this mod is easy. Buy a new adapter, remove the pipe plug, or drill it out.

stukapilot · Post by **stukapilot** » Thu Apr 14, 2011 7:57 am

Henry, I went over your how-to post and I'm having a problem understanding the purpose of the exhuast manifold EGR modification. If the purpose of the EGR modification is to reduce the oil deposit residue in the TB and intake manifold it would seem that I would'nt want to restrict the flow to the exhaust manifold, I would want to increase the flow of the vapor to the exhuast, and reduce the flow to the intake manifold. What is coating the intake of my crew is oil, not carbon. The hot oil vapor leaves the top of the valve cover and is tranfered to the intake where it coat's everything, as the oil vapor come's in contact with the hot aluminum of the intake, it turns dark brown.

Post by **HenryJ** » Thu Apr 14, 2011 11:35 am

The black in the throttle body is significantly reduced by restricting the EGR gasses that are introduced.

roadrunner · Post by **roadrunner** » Thu Apr 14, 2011 2:57 pm

According to the way your post is worded stuka you don't appear to realize the flow is from the exhaust manifold to the intake not vice-versa. Thus restricting it reduces flow to the intake and impurities from the exhaust along with it. EGR stands for exhaust gas recirculation. In short re-routing some of the exhaust from the exhaust manifolds back to the intake manifold for re-introduction to the combustion chambers via the intake manifold.

stukapilot · Post by **stukapilot** » Fri Apr 15, 2011 8:32 am

Thank you. I get it now.

roadrunner · Post by **roadrunner** » Fri Apr 15, 2011 1:09 pm

Glad to help out.

S-10CREWCAB.NET

EGR limiter

EGR limiter

Steven

Update

egr restrictor / limiter

Re: Did the throttle plate mod. today

Re: Did the throttle plate mod. today

Re: Did the throttle plate mod. today

Re: Did the throttle plate mod. today

Re: Did the throttle plate mod. today

Re: Did the throttle plate mod. today

Re: Did the throttle plate mod. today

Re: Did the throttle plate mod. today

Re: Did the throttle plate mod. today

Re: Did the throttle plate mod. today

Re: Did the throttle plate mod. today

Re: Did the throttle plate mod. today

Re: EGR limiter

Re: EGR limiter