XR4Ti Rebuild... Completed [EGR Operation Information]

atomic · Post by **atomic** » Mon Nov 07, 2005 1:07 pm

asdfsdf

turbofan · Post by **turbofan** » Wed Nov 09, 2005 12:21 am

what does removing the EGR do for ya?

atomic · Post by **atomic** » Wed Nov 09, 2005 12:54 pm

asdfdf

turbofan · Post by **turbofan** » Wed Nov 09, 2005 1:19 pm

considering my engine already has over 175k miles on it, i think i'll go with the longevity.

Post by **anglin** » Wed Nov 09, 2005 2:19 pm

what does removing the EGR do for ya?
makes it easier by not needing a flange on an aftermarket downpipe.

the function of an egr is good . ppl with a stock tune may appreciate the very small gain they get by removing it which results in a slightly leaner afr .

i wouldn't bother if i were u... it does the enviroment and your motor's longevity good.

The one thing stated above that I agree with is the simplicity of the exhaust system. Though I'm curious why exhaust would be taken from the downpipe rather than prior to the turbo. However, there is plenty of misinformation circulating about the function of EGR systems in general and the EGR system in the XR4Ti. Let's clarify.

EGR general function:

The EGR does NOT operate under circumstances where you are trying to make power, like WOT, for example. Therefore, even if it makes the air/fuel ratio leaner, slightly or otherwise, it will not make a bit of difference when your foot is on the floor. The EGR operates under cruising conditions.

The purpose of the EGR is not to lean out the air/fuel ratio. The purpose of it is (mostly) to reduce combustion temperatures by putting a mass of inert gasses in the combustion chamber. Even at 600Â° F (or whatever), it is cooler than the combustion temperatures, thereby reducing the overall temperature of the gasses leaving the cylinder.

Additionally, EGR gasses consume some of the space in the cylinder which reduces the engine's requirements for air and fuel. This means your engine consumes less gasoline while cruising.

EGR function in the Merkur XR4Ti:

By way of the emissions recall that put the vacuum delay valve in the vacuum line to the EGR valve, the EGR system on the XR4Ti may NEVER operate. It may simply sit on the engine and never function. If this theory is true:

- you'll never get reduced combustion temperatures from recirculated exhaust gasses
- you'll never have the supposed "slightly leaner" air/fuel ratio
- you'll never have the effectively reduced displacement from EGR operation while cruising

Ford reduced the operation (possibly to zero) of the EGR system with their recall. Is the EGR really that important? If the EGR system never operates, is it critical for the sake of engine longevity? Does it really help the environment? Does an EGR system on the car open up the possibility for vacuum leaks? Yada yada...

atomic · Post by **atomic** » Wed Nov 09, 2005 2:30 pm

Post by **anglin** » Wed Nov 09, 2005 3:27 pm

i never stated the EGR's function is to lean the afr . in fact when engaged, it's opposite .

You're right. I had your statement backwards. The sentence previous to the one I took issue with said leaving EGR on is good. The sentence I took issue with implied taking EGR off is good. Doh.

However, if removing the EGR causes a slight lean condition, when would a slight gain be noticed? If the EGR is only programmed to operate when cruising, do you notice a gain during cruising? Are there really power gains to be had during cruising? The EGR never would operate under WOT conditions, so it won't be slightly leaner then, if the EGR is removed. Where is the slight gain?

All the egr needs to engage is vacumn, and the diaphram will open and voila exhaust into intake.

The emissions recall modification Ford did prevents the EGR from functioning entirely or delays it by a huge amount of time. I've never seen it operate when the check valve is installed during the KOER test, which one time it should operate. The only thing it is left to do is cause vacuum leaks (and give you code 34).

atomic · Post by **atomic** » Wed Nov 09, 2005 3:37 pm

anglin wrote: You're right. I had your statement backwards. The sentence previous to the one I took issue with said leaving EGR on is good. The sentence I took issue with implied taking EGR off is good. Doh.

*thumbs up*

anglin wrote: However, if removing the EGR causes a slight lean condition, when would a slight gain be noticed? If the EGR is only programmed to operate when cruising, do you notice a gain during cruising? Are there really power gains to be had during cruising? The EGR never would operate under WOT conditions, so it won't be slightly leaner then, if the EGR is removed. Where is the slight gain?

The emissions recall modification Ford did prevents the EGR from functioning entirely or delays it by a huge amount of time. I've never seen it operate when the check valve is installed during the KOER test, which one time it should operate. The only thing it is left to do is cause vacuum leaks (and give you code 34).

Thats a good question. Will the gain be noticeable? i doubt it ..

your tests prove the EGR seldomly ever opens. So do we assume the programming compensates for that? i hope so ..

Therefor: the very small gain you'd receive from disabling the egr on a stock ecu would only happen at cruise and it will only happen seldomly because of the delay .

so there is no real point to the egr on these cars then

EDIT: If you remove it. make sure u keep the solenoid (pcm monitors that) . AND ensure u plug the hole properly !! otherwise u'll be replacing a motor hehe

Post by **anglin** » Wed Nov 09, 2005 3:56 pm

atomic wrote:so there is no real point to the egr on these cars then

Zackly.

EDIT: If you remove it. make sure u keep the solenoid (pcm monitors that) .

The EGR control solenoid is not monitored by the PCM (ECA, whatever). There's no feedback on the EGR control solenoid or the EGR valve itself. You do not have to leave the solenoid connected. You can remove the solenoid from the car and leave the plug hanging, if you want to.

Post by **DPDISXR4Ti** » Wed Nov 09, 2005 4:14 pm

I specifically recall Rick Byrnes mentioning that they didn't NEED to include EGR to pass the then-current EPA emissions output guidelines, but they left it on any way since it was already done and left a greater margin of error that the cars would pass. Bear in mind, the emissions test that a manufacturer needs to pass is WAY stricter than the typcial end-user sniff test. The two shouldn't even begin to be compared.

I hadn't heard it suggested that the recall essentially disabled the EGR entirely, but it sounds like you have some data to back that statement up Chris. I deleted EGR from my car years ago (in every conceivable way), and have no means (or intent) of returning it without buying a bunch of new parts.

atomic · Post by **atomic** » Wed Nov 09, 2005 4:30 pm

anglin wrote: The EGR control solenoid is not monitored by the PCM (ECA, whatever). There's no feedback on the EGR control solenoid or the EGR valve itself. You do not have to leave the solenoid connected. You can remove the solenoid from the car and leave the plug hanging, if you want to.

OH! well that is good news then!
i thought the pcm monitored the resistance of the solenoid to see if it was there for emission purposes ..

that's good to know, it means less clutter in my engine bay now

Offtopic: How about the overboost buzzer ... can that be removed?

Post by **anglin** » Wed Nov 09, 2005 4:40 pm

atomic wrote:i thought the pcm monitored the resistance of the solenoid to see if it was there for emission purposes ..

Nope, it's just an on/off switch. I'm pretty sure the Scorpio uses a PFE (Pressure Feedback EGR) sensor on its EGR valve though. Never owned a Scorpio, so I really have no clue.

Offtopic: How about the overboost buzzer ... can that be removed?

Yes. I think that sucker only has one wire. And don't forget about removing the buzzer too!

Brad, I'm going to eventually run a test on a car equipped with a vacuum delay valve. I'll discuss my plan here, just to be sure there are no holes in my method. I'll measure the vacuum at light, highway cruising load. I'll connect a vacuum hand pump to the delay (DeLay?) valve and duplicate cruising vacuum level. I'll time how long it takes the EGR to open. Tada!

Post by **DPDISXR4Ti** » Wed Nov 09, 2005 4:42 pm

atomic wrote:Offtopic: How about the overboost buzzer ... can that be removed?

Sure, although that's actually something I have not removed on my car. At the times it goes off, things are happening really fast all around you, so it's rare that you're actually looking at the boost gauge at that moment. An audible "gauge" is a nice feature under those conditions, to my way of thinking.

atomic · Post by **atomic** » Wed Nov 09, 2005 4:49 pm

asdfsdf

Post by **DPDISXR4Ti** » Wed Nov 09, 2005 4:49 pm

anglin wrote:Brad, I'm going to eventually run a test on a car equipped with a vacuum delay valve. I'll discuss my plan here, just to be sure there are no holes in my method. I'll measure the vacuum at light, highway cruising load. I'll connect a vacuum hand pump to the delay (DeLay?) valve and duplicate cruising vacuum level. I'll time how long it takes the EGR to open. Tada!

Sounds like a reasonable approach. Hmmm, it occurs to me as we talk about EGR, we've been told that EGR is not engaged at idle. If correct, how is that accomplished? Forget about the Ken DeLay valve

for now, as that needlessly confuses things a bit. Does the control mechanism shut down the main valve under both boost and deep vacuum?