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To EGR or not to EGR on my 5.8. That is the question.

Soren

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Aug 27, 2026
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Sorry about the length of this question, but I'm not sure how to frame it without all of the context. I'm gathering parts for the Explorer EFI and front dress conversion on a 90's roller block 5.8L engine to go in my 1966 Bronco. I purchased the lighting lower and upper many years ago for a mustang EFI conversion, but never had time to do that so I'm going to use them for the Explorer EFI conversion instead.

Now onto my questions... I've come to the point where I need to figure out whether to try and rig up an EGR system for this build. My main concerns are which heads to use/buy and what can/can't be deleted from the '97 computers . I've read a lot on this forum trying to answer this question, but I'm not certain what I'm even legally required to do. I live in Idaho, and our legislators recently got rid of all emissions testing, but I think Federal regulations require some form of EGR? So maybe I don't have an option, because EFI Guy and any others can't delete the EGR programming anyway? if there's a reasonable way to include EGR I'm no opposed to it, but I'm not entirely sure how to make it work with my manifolds and the Explorer system.

Has anyone here rigged up an EGR system on a 5.8L using the Explorer EFI system? If so, did you use the GT40p heads and exhaust manifolds? Are there other heads that I can use? Do the GT40p heads or Explorer lower intake even have EGR passages in them (I'm not entirely sure how that EGR system pulls the exhaust gasses from the drivers side, because there is only 1 tube connecting to the intake from the passenger side exhaust manifold). Also, is there an air intake that I can connect the EGR to other than the 90 degree one used on the Explorer?

I have considered trying to use the EGR passages on the lighting lower and upper, but it looks like I will need a rare and hard to find spacer that the EGR valve, etc. mount to as well as heads that can accommodate that setup, which seems fairly limiting. I'm also a little concerned about adding all of that heat to the intakes when the Explorer isn't set up that way and unsure of how that's going to impact the efficiency and how the computer functions (I'm guessing there was a reason Ford moved away from this style of system).

Thanks!
 

Timmy390

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The gt40p heads have internal passages. The lighting lower has a hole right in the middle which lines up with the hole in the explorer upper.

Not sure you can remove the emissions from the ecm's anymore. I'm 99% sure efi_guy stopped touching emissions. Other programmers might still do it.

Not FSB but my 1.6l 16 valve samurai has a non working egr due to the headers and no cat (not enough back pressure to make the valve work). The "dummy light" stays on all the time but not sure it's causing any performance issues.

Tim
 

jckkys

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I can't see a reason to do that. The OE '77 302 smog engine in my '77 EB had EGR internally routed and I simply plugged both ends. It never created any problems. I replaced that engine with an '86 351 with '96 explorer GT 40 heads that were not drilled for EGR. So the swap can go either way with no complications.
 
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Soren

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The gt40p heads have internal passages. The lighting lower has a hole right in the middle which lines up with the hole in the explorer upper.

Not sure you can remove the emissions from the ecm's anymore. I'm 99% sure efi_guy stopped touching emissions. Other programmers might still do it.

Not FSB but my 1.6l 16 valve samurai has a non working egr due to the headers and no cat (not enough back pressure to make the valve work). The "dummy light" stays on all the time but not sure it's causing any performance issues.

Tim

I have the EGR passages in the lightning upper and lower that I'm planning to use, but from looking at the Explorer upper I pulled a couple weeks ago, I don't see an EGR passage. It has 8 intake runners that are laid out in 2 groups of 4 with a space between them. Funny enough, the gasket used on the Explorer intake I have still has a hole in the center for an EGR passage, but it goes nowhere. The lower intake must not have a hole in that location either, or it would just vent into the engine compartment.

As far as the GT40p heads go, I'm curious how the EGR passages are routed (assuming there are passages of some sort... I didn't have a chance to pull the heads so I don't have any in front of me to look at). Could the exhaust gas be pulled from the driver's side head, across the lower intake manifold, and out of the exhaust manifold on the passenger side?
 

bronco italiano

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The gt40p heads have internal passages. The lighting lower has a hole right in the middle which lines up with the hole in the explorer upper.

Not sure you can remove the emissions from the ecm's anymore. I'm 99% sure efi_guy stopped touching emissions. Other programmers might still do it.

Not FSB but my 1.6l 16 valve samurai has a non working egr due to the headers and no cat (not enough back pressure to make the valve work). The "dummy light" stays on all the time but not sure it's causing any performance issues.

Tim
I think the Federal law change is was stopped all tuners from messing with emissions. Tampering with the ecm emissions is a Federal crime if I recall correctly.
 
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Soren

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I can't see a reason to do that. The OE '77 302 smog engine in my '77 EB had EGR internally routed and I simply plugged both ends. It never created any problems. I replaced that engine with an '86 351 with '96 explorer GT 40 heads that were not drilled for EGR. So the swap can go either way with no complications.

Are you running the entire Explorer EFI system, or are you using a Mustang ECU, etc.? Just curious what you did with the wires that connect to the EGR vacuum regulator and the DPFE sensor. I'm guessing I can't just remove the wires from the harness, because the computer is going to expect a signal from them?
 
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Soren

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I think the Federal law change is was stopped all tuners from messing with emissions. Tampering with the ecm emissions is a Federal crime if I recall correctly.

But how does a person determine what the emissions system is supposed to look like? Especially on a Frankenstein build like mine that has parts from a wide variety of years. Would the system need to be equivalent to whatever was installed with the computer I'm using? Or, would it need to be equivalent to whatever the year of the engine block was?

I'm not expecting anyone to be able to answer this question, because I'm guessing our lawmakers didn't even think about restomods, but maybe y'all know of some guidance that I haven't found yet. I'm sure Gary has some decent info about this as well as a few of my other questions, but I'm hoping to answer most of this through the forum so others can benefit through searches in the future. Besides... he's got to be pretty busy with all of the computer & harness mods he's doing! :)
 

ba123

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Running Megasquirt and the fact that I literally had to cut off the part of my intake that has the egr coolant passage, I've deleted mine.

Easy to do with MS though. I know there were ways with the EEC-IV ecu but not sure with the ones after that.
 

toddz69

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I have the EGR passages in the lightning upper and lower that I'm planning to use, but from looking at the Explorer upper I pulled a couple weeks ago, I don't see an EGR passage. It has 8 intake runners that are laid out in 2 groups of 4 with a space between them. Funny enough, the gasket used on the Explorer intake I have still has a hole in the center for an EGR passage, but it goes nowhere. The lower intake must not have a hole in that location either, or it would just vent into the engine compartment.

The '96-'97 Explorer upper and lower have holes in them for EGR that were deleted in later years.

Todd Z.
 

904Bronco

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Lots of moving parts here...
Each state and each county in those states could have slightly different smog rules. In the Treasure valley area of Idaho, one county did smog checks (Ada?). At some point, they determined that the money spent on the emissions testing had no benefit, so it was discontinued.

As stated above, it seems now that you are required to keep what federal emissions that your vehicle came with. Your 66 would need PCV, maybe a smog pump? Beyond that, if you chose to add EGR and say a CAT you could do that. Now here in CA, if you put a later motor into your vehicle, it must have all the smog equipment that the donor vehicle had. If EFI, then it needs to have the correct ECU for the transmission, manual vs. Auto. I put a 88* mustang motor in my former 77 EB, which gave me a headache dealing with the State. As well as having different Smog Referees that can interrupt the rules differently. So if you don't have bi-annual smog checks, like here in CA, you could, make a change.

There could be folks here and on other forums, who could jump up and down on their soap box and tell you don't need it. I'm not one of those folks, as I see the benefit of cleaner air with the EFI controlled systems. Now in the early years when Ford put the EGR spacer directly under the Carb, had temp control valves, delay valves, and a bunch of vacuum lines, what a nightmare that all is.

EFI Guy, I will not speak to what he does, he has his own guidelines he follows. But being that you have a 66 EB, I believe he would have more flexibility to delete some smog related components? I suggest that you reach out to him directly and have some dialogue.

Explorer upper and lower plenums... 96 was the first year of EFI V8. That year had similarities to the earlier EFI Mustang motors. EGR was supplied internally, from the heads cross over, to the lower plenum, then through a center hole to the upper plenum. Somewhere in the early 97 production they switched the supply to external, via a port on the Pass side exhaust manifold, then a flex pipe to the EGR valve. This style continued throughout the rest of production until 2001. You can find lowers that have cross over port, but the upper doesn't. When they ran out of that particular style, they switched to the later ones had no ports.

You talk about a lot of different components in your initial thread. If I follow correctly, you have a 351W, do you have the heads that came with it, can you use them with the intake you have? Assuming they might have a crossover port for the EGR supply... if not, you could use the Explorer exhaust manifolds to source a supply. Sounds like you need an EGR spacer, that an EGR valve would need to bolt to, if that is possible. I believe the valve size changed with the later model years, so it might not even bolt to the spacer?

This could be a challenge to keep the EGR...
 
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Soren

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Aug 27, 2026
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Lots of moving parts here...
Each state and each county in those states could have slightly different smog rules. In the Treasure valley area of Idaho, one county did smog checks (Ada?). At some point, they determined that the money spent on the emissions testing had no benefit, so it was discontinued.

As stated above, it seems now that you are required to keep what federal emissions that your vehicle came with. Your 66 would need PCV, maybe a smog pump? Beyond that, if you chose to add EGR and say a CAT you could do that. Now here in CA, if you put a later motor into your vehicle, it must have all the smog equipment that the donor vehicle had. If EFI, then it needs to have the correct ECU for the transmission, manual vs. Auto. I put a 88* mustang motor in my former 77 EB, which gave me a headache dealing with the State. As well as having different Smog Referees that can interrupt the rules differently. So if you don't have bi-annual smog checks, like here in CA, you could, make a change.

There could be folks here and on other forums, who could jump up and down on their soap box and tell you don't need it. I'm not one of those folks, as I see the benefit of cleaner air with the EFI controlled systems. Now in the early years when Ford put the EGR spacer directly under the Carb, had temp control valves, delay valves, and a bunch of vacuum lines, what a nightmare that all is.

EFI Guy, I will not speak to what he does, he has his own guidelines he follows. But being that you have a 66 EB, I believe he would have more flexibility to delete some smog related components? I suggest that you reach out to him directly and have some dialogue.

Explorer upper and lower plenums... 96 was the first year of EFI V8. That year had similarities to the earlier EFI Mustang motors. EGR was supplied internally, from the heads cross over, to the lower plenum, then through a center hole to the upper plenum. Somewhere in the early 97 production they switched the supply to external, via a port on the Pass side exhaust manifold, then a flex pipe to the EGR valve. This style continued throughout the rest of production until 2001. You can find lowers that have cross over port, but the upper doesn't. When they ran out of that particular style, they switched to the later ones had no ports.

Thanks for the detailed response! And, thanks to everyone else who has responded as well.

It sure would make things easier if I am only required to meet emissions standards that came with my '66. But, there is a chance that I'll be moving to Oregon or Washington in the next couple of years, so I guess I need to check into their requirements as well. :(. I'll check with EFI Guy to see what his requirements are for modifying the EGR system on the computers I have.

As far as keeping the EGR system goes, I can see a benefit, because from what I understand it slows / lowers the burn temperature in the combustion chamber. I don't want to end up with increased pinging, because I rigged the computer up to some fake/non functioning sensors. If it keeps noxious gasses out of our air that's a bonus to keeping it as well.

You talk about a lot of different components in your initial thread. If I follow correctly, you have a 351W, do you have the heads that came with it, can you use them with the intake you have? Assuming they might have a crossover port for the EGR supply... if not, you could use the Explorer exhaust manifolds to source a supply. Sounds like you need an EGR spacer, that an EGR valve would need to bolt to, if that is possible. I believe the valve size changed with the later model years, so it might not even bolt to the spacer?

This could be a challenge to keep the EGR...

Very true! I'm juggling quite a few parts here in an attempt to put this together. The roller block 351W / 5.8L engine I have has barely any piston wear, so I'd much prefer to use it to a 5.0 that's got a lot less life on it. Unfortunately, it came with the E7TE heads on it, which don't flow very well and will likely limit the power gains of the Explorer EFI system. Consequently, I'd prefer to put my $$'s into a decent head than pay for the E7's to be rebuilt. I am hoping to find a newer aftermarket head that makes sense and is reasonably priced (or use the GT40Ps). As you mentioned, I also am a little concerned with sourcing the EGR spacer, valves to fit it, and finding a way to make that work with the Explorer computer.

IF the EGR system on the later model Explorers functions by pulling exhaust gasses from the passenger side exhaust manifold and doesn't rely on passages in the heads to function then I could theoretically use any head... as long as I use the Explorer exhaust manifolds. But, I'm not sure if that is how the later model Explorer EGR system works... Any insights?
 

Broncobowsher

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37,049
A good EGR is nice. Lots of people have had bad experiences and that has soured some people on it.

The upper EGR hole went away mid '97 when the P-heads arrived. They still had EGR, but the heads didn't have the provision to do it internally. So it was moved external.
 

ntsqd

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CA engine swap rules don't apply to you, but they all boil down to the configuration must match the donor from the first sensor to the last sensor. The only non OEM parts allowed between those two sensors are those with a E.O. number that applies to the donor. Usually the first sensor is an ambient air temp or the MAF, and the last sensor is an O2 sensor in the exhaust. Everything between them must be unmodified OEM parts or unmodified E.O. numbered parts. A Frankenstein won't fly because that combo hasn't been EPA tested for emissions compliance and CARB isn't smart enough. It used to be that an engine emissions upgrade (i.e. adding OEM EFI to the existing carbed engine) was recognized, but the nuances got to the point where they're not worth the trouble.

I have an engine that has AFR aluminum heads (with an E.O. number) on it that has the EGR ports in the ends of the heads. The application for that engine sources EGR gas from the RS exhaust manifold, so the engine builder put plugs in those ports and boy were those plugs spendy for what they are! Advantage of the AFR heads is being aluminum they can stand more static CR and they cool better than iron heads.
 

904Bronco

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There is nothing wrong with the E7 heads, far better than the E6 heads that came before them. E7's were on late model mustangs. GT40 would be an upgrade and GT40P beyond that.

My current build is 88 LTD roller 302, it had the E6 heads. I had the E7 heads, changed out the low compression pistons, added an explorer cam, and with 4:11 with 31's it runs me down the road without issue.

I image with a 351 and a basic setup, your Bronco would move down the road just fine. I caution having a mixture of parts, sometimes the mix doesn't always equate to high HP.
 
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Soren

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Thanks for your explanation the CA engine swap rules ntsqd. I'll try to track down any guidance I can find for Oregon and Washington. When you mention that the sensors must match the donor it sounds like I would be required to maintain the speed density system that my 5.8L came with (Fx50 donor truck), but that won't fit under the hood. Hopefully Oregon and Washington are more lenient?
 
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Soren

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As far as the E7 heads go, they are an option, but I'm pretty sure I'll spend at least $700 on a rebuild + new springs and milling down the pedestal's so I can run roller rocker arms. If I'm going to spend that much I'd certainly prefer to get something that flows better, because the heads will definitely be the bottleneck on a 5.8 with the Explorer EFI system. Even the GT40Ps were a little restrictive for the 5.0 and they are a decent improvement over the E7's.
 

ntsqd

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CA is a stickler, it's not just the sensors, it's everything! The tube that the IAT is mounted in has to be unmodified OEM / OEM replacement or have an E.O. for the donor. The last O2 sensor needs to be in the unmodified OEM / OEM replacement exhaust tube or an unmodified part with an E.O. number for the donor. Before and after those sensors is wide open, but between them has to be stock parts or CARB certified ("Executive Order" aka "E.O.") non OEM type replacement parts. One LS swap that I helped on had to use a K&N performance filter kit with an E.O. number in order to fit. We had to modify one of those parts (A no-no, but it wouldn't work any other way) and hope that the Referee wasn't familiar with that particular kit enough to spot the mod. He wasn't or he didn't care, one of the two.

Some '95s had a MAF and were OBD II. If you claim it is a '95 engine, and it matches that configuration, then I don't see how they could argue against it. That gets you into a MAF and OBD II, but if this were KA it would also require use of the truck intake. Which we all know is a no-go. I have seen one such conversion done in an EB many years ago. I didn't know what I was seeing until long after it was gone. It is entirely possible, not that I'd condone such a thing, that it could get labeled with the truck intake in place (& no hood), only to be swapped for the intake parts that fit sometime later. ;) I seriously doubt that you'll need to consider such shenanigans in your state. I'll be kind of surprised if you have to do anything beyond show up and pay the fees to register it.

The truck 5.8L emissions legal speed parts out there with E.O. numbers all stop being certified at '95 because they were designed and intended to be used on the first gen Lightnings, which stopped at the end of the '95 model year.

This is my 96 FSB's intake, note the EGR valve:
i-r28cXfV-M.jpg
i-zPK6Gt4-M.jpg


Seems like that valve on a spacer between the TB and the intake with a tube down the RS manifold could get you a functioning EGR, even if it's not a factory set-up.
 

jckkys

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My EB is a '68 for emission porpoises as per Az laws. The Feds only call for PVC on 68's The title and multiple VIN numbers all match. The heads are not "P" versions but are GT40. The long EGR hole connecting all the exhaust ports was never drilled. I bought them from a JY in Flagstaff. The doner vehicle is unknown. Nothing about my EB has anything to do with Ca. Yea. I believe it was and still is a carbureted engine. So the engine compartment looks like a '68 EB. That's more important to me than EFI.
 
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Soren

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ntsqd,

Thanks for the additional information (I had no idea what the E.O. # was, etc.) and idea for using some of the original donor EGR system... The manifold and EGR system in your picture look very familiar. They were the 1st things I gave away once I realized that the manifold wouldn't fit under my hood. 😅

At this point it appears like I've got three options available if I want to build something that "should" pass most state emissions testing criteria other than CA.:
  1. Try to retrofit the '97+ EGR system onto my 5.8L and plug the holes in the lightning intakes. Find some heads that are street legal for use on a 97+ Explorer.
  2. Try to recreate the '96 Explorer EGR system which should work with my lightning intakes. Find some heads that are street legal for use on a '96 Explorer.
  3. Try to recreate a '95 MAF/OBD II system. Going to have to see if I can use much of the Explorer harness/parts I've already pulled and figure out whether they will work with the lightning intakes. Not even sure if this system uses a distributor... Guessing parts for this are going to be super hard to find?
 
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