Engine (EGR Deleted) Solution the hotter combustion chambers?

Mustang5L5 · Jan 31, 2026

PonyGTrider said:
On your last paragraph I think the resistors are just to keep the check light off and one thing I’m not sure how it works; does the computer disables the EGR function if the pint is static? (No vacuum hose or by way of resistors plug)
I heard that when the computer sees no activity from the EGR it registers as “non operating” and disables that function, but only if the check is blinking? I’m confused about that whole sequence…

They way it works is the EGR resistors mimic the signal that the EGR position sensor would send to the ECU and, in this case, send the signal the EGR is closed.

The ECU sees the signal and logs a code. I forget which one it is but it’s an EGR stuck closed code, or some wording along those lines.

The ECU then disables the EGR function. No timing or fuel adjustments. But the code generated doesn’t display the CEL.

You don’t need the resistors at all. You can just unplug the EGR completely, and the ECU will see this and set a code and also disable the EGr function. But it will trigger the CEL.

PonyGTrider · Jan 31, 2026

Mustang5L5 said:
They way it works is the EGR resistors mimic the signal that the EGR position sensor would send to the ECU and, in this case, send the signal the EGR is closed.

The ECU sees the signal and logs a code. I forget which one it is but it’s an EGR stuck closed code, or some wording along those lines.

The ECU then disables the EGR function. No timing or fuel adjustments. But the code generated doesn’t display the CEL.

You don’t need the resistors at all. You can just unplug the EGR completely, and the ECU will see this and set a code and also disable the EGr function. But it will trigger the CEL.

I think I’m getting to understand how that system works. Will wait until I have to remove the lower intake to plug the EGR port on the head and procede with the rest of the deletion, that will keep the lower, upper, and throttle body cooler.

Thank you

GOvert · Feb 1, 2026

Cooler is better. Several years back, that was my initial common-sense thoughts on it all was how are warm exhaust gasses going to keep the incoming air charge cooler, especially here in the hot humid southeast US?
It is good that the little metal block offs come with the intake gaskets.
I haven't dug into EEC-4 Fox body pcm files to see if the EGR function can be switched off, but just two days ago while working with a 1999 EEC-V Ex 5.0 file, I found a setting that was more or less an ambient temperature of 32F (at a hair above freezing) must be met before the pcm will monitor the EGR.
I changed the temp to 255 (a good temp for smoking pork ribs). I don't think any of us will be driving around in 255F! The change is an experiment.
Friday during the first test of starting/running and turning off 8 times, no trouble codes were posted. Monday the pcm will be installed again and do about 80 miles of driving over a two-day period to see if DTCs post or not.
This spring I will be working with a 1989 Mustang 5.0/Auto Mustang ECM with EGR delete (EEC-4 OBD1). I'll add something later having to do with that.

No, I'm not a professional tuner. Just an old school guy wanting to use newer Ford 5.0s in antique Mustangs!

PonyGTrider · Feb 1, 2026

GOvert said:
Cooler is better. Several years back, that was my initial common-sense thoughts on it all was how are warm exhaust gasses going to keep the incoming air charge cooler, especially here in the hot humid southeast US. It is good that the little metal block offs come with the intake gaskets.
I haven't dug into EEC-4 Fox body pcm files to see if the EGR function can be switched off, but just two days ago while working with a 1999 EEC-V Ex 5.0 file, I found a setting that was more or less an ambient temperature of 32F (at a hair above freezing) must be met before the pcm will monitor the EGR.
I changed the temp to 255 (a good temp for smoking pork ribs). I don't think any of us will be driving around in 255F! The change is an experiment.
Friday during the first test of starting/running and turning off 8 times, no trouble codes were posted. Monday the pcm will be installed again and do about 80 miles of driving over a two-day period to see if DTCs post or not.
This spring I will be working with a 1989 Mustang 5.0/Auto Mustang ECM with EGR delete. I'll add something later having to do with that.

No, I'm not a professional tuner. Just an old school guy wanting to use newer Ford 5.0s in antique Mustangs!

This sounds interesting to me. Hope to see some results on those tests.
Thank you for sharing.

90trunk · Feb 3, 2026

There is a Scalar in the EEC-IV to enable/disable the EGR:
Turn off EGR with "EGR Type": 0= Present/On 2 = None/Off

You can also configure the Thermactor settings with the
“Aux Hardware Present” Scalar: 0 = None/Off 1 = Present/On

GOvert · Feb 4, 2026

@90trunk Which tuning type, or camp have you been working in? I have access in BE to the Fox body 5.0 files and the files in the TunerProRT/decipha method. I haven't yet to look deep into either of these. This spring I/we will be trying to do some MAF adjustments on the '89.
I'm very young in all of this. Right now, I'm just able to do the basics like switch off PATS in 1998 to 2004 pcm and in the earlier EEC-IV stuff I would be able to flip those EGR switches, thermactor settings.
@PonyGTrider I have capabilities to program J3 chips for EEC-IV eecs or ecms. But I want to do such to my '89 Fox body first. The '89 convertible is currently in winter storage and won't come out until sometime in April. I can't do anything with Moates chips, just T.I. Performance chips.

90trunk · Feb 4, 2026

GOvert said:
@90trunk Which tuning type, or camp have you been working in? I have access in BE to the Fox body 5.0 files and the files in the TunerProRT/decipha method. I haven't yet to look deep into either of these. This spring I/we will be trying to do some MAF adjustments on the '89.
I'm very young in all of this. Right now, I'm just able to do the basics like switch off PATS in 1998 to 2004 pcm and in the earlier EEC-IV stuff I would be able to flip those EGR switches, thermactor settings.

I'm running a Moates F3V2 chip setup using Decipha/EFIDynotuning.com's GUFX/X3Z bin file. I'm working with TunerPro RT and saved the files with Moates GUFB.xdf file. This combo resulted in having no checksum errors (Code 15) when running the KOEO tests. I went this route when I sent an old school Pro-M 77mm to be calibrated for my X3Z, 70mm MAS, and 24# injector combo. The mass air transfer function graphs between the 70mm and 77mm units almost laid on top of one another, but I know everything is correct now.

PonyGTrider · Apr 23, 2026

Since more questions are on the list I have to resurrect this forum.

Starting with the premise that when we deleted the anti-smog system obviously removed the rear heads crossovers pipe and have those holes plugged, is it fair to assume that my EGR is pulling exhaust gases ONLY from one head???
Because my trick flow lower intake has only one port on the passenger cylinder head but none on the driver side.

There are a few articles that talk about the effects of canceling the EGR system that the temperature inside the combustion chambers increases by 100 - 200 degrees.
So in my case is my driver side cylinder head is hotter than the passenger side???

So what if I completely delete the EGR?
As I will be using the 1250S-3 they don’t have the hole for the EGR port on the head.

Please let me know your opinions

90trunk · Apr 23, 2026

PonyGTrider said:
---snip--- is it fair to assume that my EGR is pulling exhaust gases ONLY from one head???
Because my trick flow lower intake has only one port on the passenger cylinder head but none on the driver side.
---snip---
So in my case is my driver side cylinder head is hotter than the passenger side???
---snip---
So what if I completely delete the EGR?
As I will be using the 1250S-3 they don’t have the hole for the EGR port on the head.

Yes, the EGR system is being supplied from one cylinder head in your present configuration.

No, both cylinder heads will be operating at approximately the same temperature. The EGR system disperses the exhaust gasses through the entire intake at the EGR valve assembly.

Consider adding something more substantial to block the exhaust gasses. Relying on a bare 1250-S3 gasket to hold up to sustained exhaust flow is a big ask.

PonyGTrider · Apr 23, 2026

90trunk said:
Yes, the EGR system is being supplied from one cylinder head in your present configuration.

No, both cylinder heads will be operating at approximately the same temperature. The EGR system disperses the exhaust gasses through the entire intake at the EGR valve assembly.

Consider adding something more substantial to block the exhaust gasses. Relying on a bare 1250-S3 gasket to hold up to sustained exhaust flow is a big ask.

Ops!!! I just realized that was a dumb question
Right now the top end is off because of a suspicious vacuum leak and one thread for the lower intake damaged.
Right now I’m debating if go ahead and block the EGR port on the head since I’m using the 1250S-3 gaskets. If I decide to go that way I will cut a piece of thin body filler spreader to avoid burning the gasket.

And in case I go that route how to deal with the extra heat and potential pinging?Just backdown the timing, or what else? How bad the heat will be? Something manageably??

Thanks man

AeroCoupe · Apr 24, 2026

You have the lower off the car so why not just tap the hole in the lower (between the upper and lower) and put a recessed pipe plug in it?

Found a thread on this very subject:

M

Thread 'Best way to block hole in lower intake GT40'

Feb 9, 2007

Doing a gt40 manifold swap on my 88 gt. The manifold is off an early 97' explorer so it has the hole in the middle of the ports on lower. Just wondering what did everybody do to solve this problem other than just using the egr. thanks

PonyGTrider · Apr 24, 2026

AeroCoupe said:
You have the lower off the car so why not just tap the hole in the lower (between the upper and lower) and put a recessed pipe plug in it?

Found a thread on this very subject:

M

Thread 'Best way to block hole in lower intake GT40'

Feb 9, 2007

Doing a gt40 manifold swap on my 88 gt. The manifold is off an early 97' explorer so it has the hole in the middle of the ports on lower. Just wondering what did everybody do to solve this problem other than just using the egr. thanks

mustang30288

Replies: 15

Forum: Fox 5.0 Mustang Tech

Yes I could do that but the point I trying to make is, the lower intake is off too and I’m using the steel core 1250S-3 that has no hole for the EGR port on the head so why should I I cut a hole on the gasket and cap the hole in between the upper and lower?
I’m tempted to do what I just described but the increase of temperature in the combustion chambers increasing the risk of detonation at partial throttle and the hit on fuel economy which is a pathetic 9.5 miles per gallon and I’m trying to troubleshoot in another post here called “Xtremely high fuel consumption” is making me think more than twice.

GOvert · Apr 25, 2026

GOvert · Apr 25, 2026

You need this AEM AFR gauge kit to see what is going on with your air/fuel mix. In a notebook or notecard, every time that you make a change to the 5.0, record the readings, cold and hot. This includes switching to different grades of fuel.
AEM AFR gauge kit

PonyGTrider · Apr 25, 2026

GOvert said:
You need this AEM AFR gauge kit to see what is going on with your air/fuel mix. In a notebook or notecard, every time that you make a change to the 5.0, record the readings, cold and hot. This includes switching to different grades of fuel.
AEM AFR gauge kit

I’ve seen AEM AFR gauges at lower price in Ali Express, are them any good or get them from another site?

Noobz347 · Apr 25, 2026

PonyGTrider said:
I’ve seen AEM AFR gauges at lower price in Ali Express, are them any good or get them from another site?

[IF] they are real.

Are they? No idea.

GOvert · Apr 26, 2026

I purchased my AEM AFR kit directly from AEM.

86HO5.0 · Apr 26, 2026

PonyGTrider said:
I’ve seen AEM AFR gauges at lower price in Ali Express, are them any good or get them from another site?

Buy one from Summit/Jegs/LMR. They're about $220 shipped.

DO NOT buy a cheap POS from Aliexpress. They're a knockoff, might as well burn your money.

86HO5.0 · Apr 26, 2026

Please hurry up and buy one. I feel like a broken record suggesting a wideband.

Have a good day sir!

gkomo · Apr 26, 2026

Bought my AEM wideband from LMR. It was on par with summit and the like websites.

Engine (EGR Deleted) Solution the hotter combustion chambers?

Mustang5L5

That is…until I whipped out my Bissell

PonyGTrider

GOvert

PonyGTrider

90trunk

Active Member

GOvert

90trunk

Active Member

PonyGTrider

90trunk

Active Member

PonyGTrider

AeroCoupe

lube between the nut and the face. I know my lubes

Thread 'Best way to block hole in lower intake GT40'

PonyGTrider

Thread 'Best way to block hole in lower intake GT40'

GOvert

GOvert

PonyGTrider

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

GOvert

86HO5.0

Active Member

86HO5.0

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gkomo

now i can hopefully expect to receive the shaft

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Engine (EGR Deleted) Solution the hotter combustion chambers?

That is…until I whipped out my Bissell

Active Member

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lube between the nut and the face. I know my lubes

Stangnet Facilities Maint Tech... Er... Janitor

Active Member

Active Member

now i can hopefully expect to receive the shaft

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