EGR and bypassing EGR spacer coolant... debate

[mob]

:OT:

It's neat to see someone on SN from Winter Springs, I used to live there when I was a tot.

:OT:

haha do you remember where you lived? Small little town, its getting huge though, I live right across from indian trails and keeth, the middle school and elementary school, if you lived here when you were young you probably went there.

 

[Boss 351]

I think next season I'll run without the EGR system, but it will be blocked off at the heads, no EGR coolant lines, EGR delete plate (replaces the EGR spacer), and a phenolic spacer. I'll test the temperature of the intake with a pyrometer before taking apart the engine so I'll eventually post before and after numbers.

So I guess that's why the 94 got an external EGR system and no need for coolant lines in the intake.

HEre's some good info: http://www.my5oh.com/forum/viewtopic.php?t=70

 

[1990Coupe]

IF the coolant didn't serve a purpose, Ford would not have bothered routing it to the EGR.

It is there to cool the EGR gasses.

If you remove the EGR, then it is best to plug the egr passages at the heads.

If you unplug the egr valve, it is disabled in the computer. The 'alternate' strategy the computer uses when the egr seems to disapear, will work the same as turning off the egr function with the tweecer. In theory anyway.


I wish I still had my egr setup.
I removed it when doing the 351w conversion, and never figured out how to get it back in there.



jason

Is this a fact? im only asking because i bought my car, and the coolant lines were already bypassed. The little vac sensor that hooks to the egr was also disconnected. Why cant i just take out the EGR spacer all together? the egr is still plugged in, and i do not have any egr tubes running to the heads. With this still being hooked up to the computer, could it be causing my idle surge and can i simply unplug it, and either remove the whole spacer, or at least block off the port? here's a pic (I KNOW its dirty, im also having an pcv/oil issue i believe and i left it like that to show what im dealing with)

View attachment 427566

View attachment 427568

 

[Darkwriter77]

Am I seeing that right? An Edelbrock BBK throttle body spacer?

And by EGR tubes to the heads, are you referring to the smog pump crossover tubes that go around the back to both heads? ... because that's not necessarily related to the EGR valve, itself.

I've got mine blocked off similarly with a couple of vacuum caps over the nipples on the EGR spacer, but I didn't unhook the vacuum line from the EGR valve - it still works, no surging/bucking, and it passed smog that way, so what the heck.

I guess Boss 351 has the right idea, as far as blocking everything off if you're trying to keep heat off of the upper manifold - phenolic spacer, EGR passages blocked/bypassed, the works. But that would basically fall under the whole smog system delete process, anyway - fine if you're not in a Smog Nazi area, but not an option for chumps like me in the Phoenix area.

This sucks ... here I am, starting to think about having to re-invest in a heater pipe so I can reconnect those stupid little coolant lines, if that's what is causing my upper-RPM pinging. And part of the reason (aside from my old heater pipe rotting apart) I bypassed those lines to begin with was because it was leaking a little bit of coolant into my throttle body area - either the gasket(s) was/were going bad, or the spacer is cracked/rotted out inside.

 

[1990Coupe]

Am I seeing that right? An Edelbrock BBK throttle body spacer?

And by EGR tubes to the heads, are you referring to the smog pump crossover tubes that go around the back to both heads? ... because that's not necessarily related to the EGR valve, itself.

I've got mine blocked off similarly with a couple of vacuum caps over the nipples on the EGR spacer, but I didn't unhook the vacuum line from the EGR valve - it still works, no surging/bucking, and it passed smog that way, so what the heck.

I guess Boss 351 has the right idea, as far as blocking everything off if you're trying to keep heat off of the upper manifold - phenolic spacer, EGR passages blocked/bypassed, the works. But that would basically fall under the whole smog system delete process, anyway - fine if you're not in a Smog Nazi area, but not an option for chumps like me in the Phoenix area.

This sucks ... here I am, starting to think about having to re-invest in a heater pipe so I can reconnect those stupid little coolant lines, if that's what is causing my upper-RPM pinging. And part of the reason (aside from my old heater pipe rotting apart) I bypassed those lines to begin with was because it was leaking a little bit of coolant into my throttle body area - either the gasket(s) was/were going bad, or the spacer is cracked/rotted out inside.

yea its an edelbrock bbk spacer and tb .. yes i ment the smog pump cross over tubes.. My question is (im having a brain freeze here) how is there hot exhaust gasses in the spacer that need to be cooled in the first place?? and do you think i should re-hook up that vac sensor to the EGR and keep it all intact? or should like i said, remove the whole thing entirely? im wondering that if it really doesnt make a difference if its connected or not, just removing the whole spacer..

I live in New Jersey. My car is not my DD.. So to get around the whole emissions thing (yes NJ is nazi's with that as well ) i registered my car with collector status.. So when i go for inspection, they basically make sure that my odometer is working, and thats it i pass.. doesnt matter if 3 tires are flat and i pushed it in there, it will pass with a working odometer.. the catch is (of course, always a catch!!) i can only drive it 3000 miles a year.. Which for me is fine - because i only drive it on weekends, and in the winter its stored. If i ever came close to going over, id disconnect the speedometer at the dash to stop it from rolling anymore but shhh i didnt say that

 

[Luvmy88]

Not trying ot hijack the thread, but since it's related - how exactly does one block off the egr passages in the heads? Gasket, plate or someting simliar?

EDIT: Found my answer, comes w/ 1250 gasket set.

 

[joel5.0]

Here are my 2¢ on the subject:

The coolant lines connected to the EGR spacer are for cooling purposes, as contained in the EGR system description:

The EGR valve is mounted on a throttle-bore-sized cast-aluminum spacer plate sandwiched between the throttle body and the upper manifold plenum section. Recirculated exhaust gases are fed back into the inlet track through this coolant-cooled spacer plate.

A functional EGR system will cause the spacer to overheat and could cause other failures (TPS for example....I'll explain in a while). I mentioned functional, b/c even with all the connections in place, an EGR failure code = EGR system delete....EGR valve is not opened by the system until all EGR codes are cleared and not repetitive. Most of the Ford cases I've worked on, have the EGR system deleted....and they don't know about it (customers). If the EGR system is OK, and is constantly activated w/out the coolant lines installed....the overheating of the spacer could cause premature TPS failures.

All the cases I've worked, with the EGR spacer coolant lines removed, have been comeback cases for TPS sensor failures in a 3-10 mo. period once the EGR codes were corrected....why?....TPS sensor failure due to overheating.....regardless of the replacement sensor used. The first two cases confirmed it (1993)...and so did the last one ('86 4-eyed SD customer - 6-mo. ago) ....a reconnection of the coolant lines, or an EGR function delete (as simple as plugging the EGR valve vacuum line to force a code 33 to be logged)....solved the TPS premature failures.

Hope this helps.

 

[1990Coupe]

Here are my 2¢ on the subject:

The coolant lines connected to the EGR spacer are for cooling purposes, as contained in the EGR system description:



A functional EGR system will cause the spacer to overheat and could cause other failures (TPS for example....I'll explain in a while). I mentioned functional, b/c even with all the connections in place, an EGR failure code = EGR system delete....EGR valve is not opened by the system until all EGR codes are cleared and not repetitive. Most of the Ford cases I've worked on, have the EGR system deleted....and they don't know about it (customers). If the EGR system is OK, and is constantly activated w/out the coolant lines installed....the overheating of the spacer could cause premature TPS failures.

All the cases I've worked, with the EGR spacer coolant lines removed, have been comeback cases for TPS sensor failures in a 3-10 mo. period once the EGR codes were corrected....why?....TPS sensor failure due to overheating.....regardless of the replacement sensor used. The first two cases confirmed it (1993)...and so did the last one ('86 4-eyed SD customer - 6-mo. ago) ....a reconnection of the coolant lines, or an EGR function delete (as simple as plugging the EGR valve vacuum line to force a code 33 to be logged)....solved the TPS premature failures.

Hope this helps.

so what your basically saying is that if the egr valve is throwing a code, it will not be activated by the computer..

so in my case (vac is plugged, and its throwing a code) i can remove the EGR, and basically the entire egr plate? or should i just cap off where the egr was?

 

[Fett]

Even removing the EGR plate, blocking the EGR off, or removing the vac line...the intake still gets hot. If you want to keep the hot exhaust gasses from entering the intake, you will need to block off the ports on the head. All the EGR does is allow those hot exhaust gasses to actually enter the combustion chamber via the intake. But the hot hasses will still enter the "hidden chamber" in the intake and cause the intake itself to heat up.

That is the theory behind the coolant lines, they supposedly help cool the exhaust gasses as they actually enter the throttle body, via the EGR valve.

That is basically why removing the EGR has no benefit. The EGR only opens while cruising anyway. If you want to really delete the EGR and the heating effect it causes, you want to use the proper gasket and block those hot exhaust gasses from coming in contact with the intake in the first place.

At least, that is my understanding.

 

[joel5.0]

so what your basically saying is that if the egr valve is throwing a code, it will not be activated by the computer..

so in my case (vac is plugged, and its throwing a code) i can remove the EGR, and basically the entire egr plate? or should i just cap off where the egr was?

View attachment 427421 ....that's the "failsafe" mechanism designed into the logic. As Fett mentions, the best way to remove the effects of the hot gases would be to block the crossover passages at the head-intake joint, but not having the exhaust gases moving into the intake (EGR opening) will not cause the temperature to rise that much, since it's the flow of the exhaust gases what causes the temperature to rise.....reason why you could even use a rubber cap to plug an Explorer EGR tube at the EGR valve end w/out causing the plug to be burned off. If you open a hole on the rubber plug, causing an exhaust leak (gases flowing), it'll overheat and burn off the rubber plug.

 

[1990Coupe]

cool!

ok the more im starting to understand, the more im feeling im understanding less, i thought that the tubes on the back of the heads is how the EGR gasses make there way to the TB.. how are the hot gasses getting to the intake if those tubes on the back of the heads are gone. is it getting there thru passages on the lower intake? sorry i feel really dumb right now

 

[Boss 351]

the tube in the back of the heads are part of another smog system. It sends oxygen in the head's exhaust port to burn off unburnt fuel from the combustion... also sends oxygen to the cats so they can do their job as well. It has nothing to do with the EGR.

The EGR on the fox get's the exhaust gasses from the heads, passes through the lower intake, into the upper intake passage and into the EGR spacer where the EGR valve is located. EGR on the SN95 has a tube directly from a header so they don't have hot exhaust gasses flowing through the intake manifold.

 

[Boss 351]

Say we just removed the EGR system (blocked at heads, EGR delete plate) and allow the computer to automatically prevent the EGR from running by allowing it to see the EGR isn't working.

Now since a running EGR system will function at part cruise right. The scenerio is that where driving down the highway at cruise speeds. The computer won't advance timing and reduce the injector cycle, so in theory the combustion chamber won't run any hotter, right? We will however see a loss in fuel economy during cruise.

BUT I'm wondering for those of us with gears, will the computer still use a cruise strategy since it will depend on the TPS and VSS sensors? We will need more throttle to "cruise" at 70mph with gears. So basically once you've started modding the car, the EGR system won't serve much purpose.

 

[joel5.0]

Say we just removed the EGR system (blocked at heads, EGR delete plate) and allow the computer to automatically prevent the EGR from running by allowing it to see the EGR isn't working.

Now since a running EGR system will function at part cruise right. The scenerio is that where driving down the highway at cruise speeds. The computer won't advance timing and reduce the injector cycle, so in theory the combustion chamber won't run any hotter, right? We will however see a loss in fuel economy during cruise.

BUT I'm wondering for those of us with gears, will the computer still use a cruise strategy since it will depend on the TPS and VSS sensors? We will need more throttle to "cruise" at 70mph with gears. So basically once you've started modding the car, the EGR system won't serve much purpose.

Nope....you're assuming the IPW portion, which is basically controlled by the A/F tables and adaptive strategy learned via the O2's input (vs. target stoich). The logic calculates a spark advance "addition" DUE to the EGR....if it encounters an EGR code, the spark timing addition DUE to the EGR = 0°. A/F feedback will continue to be processed and adaptive corrections take place.

The CC will run hotter and NOx levels will climb @part throttle, but O2's will continue to "correct" the system based on those "new" readings under part-throttle conditions....as long as the "added" TPS signal voltage is below 2.71vdc over the minimum closed-throttle reading while cruising, WOT tables/strategy are/is not used.....LUK