EGR Discussion
- Thread starter kz9
- Start date
How I see it, the EGR helps with burning off leftover fuel/hydrocarbons as it recirc's exhaust gases back into the combustion chambers. This helps the Cat's life-span.
Now if I was to just put a breather on an EGR it would still see flow and wont throw a CEL? But say I was under boost, will I lose boost if it was open? Or say if I was just sittin at a light will I lose Vac? I can't see ethier of these things happening cause the other end is just open into the exhuast.
Anyone know the operating cycles of the EGR? And how does it not cause Vac loss?
Now if I was to just put a breather on an EGR it would still see flow and wont throw a CEL? But say I was under boost, will I lose boost if it was open? Or say if I was just sittin at a light will I lose Vac? I can't see ethier of these things happening cause the other end is just open into the exhuast.
Anyone know the operating cycles of the EGR? And how does it not cause Vac loss?
I have come to the sad conculsion that ethier no one know s*** about anything or that the people with knowledge on this topic wont post cause they see my post count and just ignore it.
I know my way around most vehicles and just want to have a simple discussion with others of the same IQ about this topic.
If you think I don't my pro, just ask for my mod's list, cause I have done everything myself.
I know my way around most vehicles and just want to have a simple discussion with others of the same IQ about this topic.
If you think I don't my pro, just ask for my mod's list, cause I have done everything myself.
ANYWAYS....back on topic.
If im correct, our cars control the EGR with 2 things. TPS and Engine temp. When the engine is cold the egr is shut, it opens when it reachs operating temp. Thus in turn when the car is at WOT the EGR shuts, and when under it feathers the valve so, to recirc exhaust gas and also this helps to lower combustion chamber temps.
So heres where I stand. Last season I put the car back on the road. Not with in 3 days I got the insuffisent flow code for the egr. The car ran great, no idle problems, tuning issue's, or high exhaust temps. I had plans for the car this winter so i decided to leave it on and change it this winter.
The car ran great all season and no probs.
I removed it this winter to find that it was siezed shut and that it was never opening. Mazda had released a service bulletin for this problem and I was able to get the new revised one for no cost.
On the revised one, it has a vaccum line on it? So know is the EGR controlled by Vac too? Or is this just an aid to the soleinod.
So I can see that on a completly stock ecu controlled engine needing a EGR because the stock maps and such are programmed to have and EGR opening and shuting at certin points.
BUT
I here people saying that you don't need one on standalone unit but still need one on Piggy-back units likes E-manage.
If some people wth piggybacks where to start to just put a breather on the EGR would it cause a lean condition? Or could they just control it with there tune.
If im correct, our cars control the EGR with 2 things. TPS and Engine temp. When the engine is cold the egr is shut, it opens when it reachs operating temp. Thus in turn when the car is at WOT the EGR shuts, and when under it feathers the valve so, to recirc exhaust gas and also this helps to lower combustion chamber temps.
So heres where I stand. Last season I put the car back on the road. Not with in 3 days I got the insuffisent flow code for the egr. The car ran great, no idle problems, tuning issue's, or high exhaust temps. I had plans for the car this winter so i decided to leave it on and change it this winter.
The car ran great all season and no probs.
I removed it this winter to find that it was siezed shut and that it was never opening. Mazda had released a service bulletin for this problem and I was able to get the new revised one for no cost.
On the revised one, it has a vaccum line on it? So know is the EGR controlled by Vac too? Or is this just an aid to the soleinod.
So I can see that on a completly stock ecu controlled engine needing a EGR because the stock maps and such are programmed to have and EGR opening and shuting at certin points.
BUT
I here people saying that you don't need one on standalone unit but still need one on Piggy-back units likes E-manage.
If some people wth piggybacks where to start to just put a breather on the EGR would it cause a lean condition? Or could they just control it with there tune.
The only way you could "control" your EGR is to go with a complete standalone and use and aux output. But I to have the same question and trying to figure this out. I currently have my EGR "venting/sucking" to a breather. I was thinking of running it to a vacume "box". i did have it blocked off and my car ran bad and have trouble maintaining idle. So hopefully someone that knows for a fact when the EGR opens. My question is if the EGR is open under lite load then it is possible to push pressure into the exhaust? this dosnt make sense?
CrazyCaker
Member
- :
- '10 Stang GT / '06 Mazda5 GT
subbing.
I'm running mine open tube right now, but I plan on getting one of 505zoom's IM without the egr.
I'm running mine open tube right now, but I plan on getting one of 505zoom's IM without the egr.
Just going to deal with the CEL? I'm curious about this as well (also interested in 505's IM) but I haven't seen any way around this. A lot of people put breather filters on a cut pipe but I don't see how this is a good idea - wouldn't this allow unmetered air into the IM when the EGR opens? Also, does the EGR have to see "flow" to avoid throwing a CEL? I'm curious because would it be possible to block off the port on the IM and then leave the EGR still plugged in but say, zip-tied somewhere to the firewall. IE, the valve would still open and shut and operate as otherwise told by the ECU but it wouldn't be doing anything. Sort of like removing the VTCS actuator but leaving the solenoid plugged in.
the EGR valve is one part of a complex closed-loop control system. the ECU has several inputs from which it derives what's going on inside the combustion chamber. it has a few control points, the EGR valve being one. if the EGR isn't letting the right amount of exhaust air in, the oxygen/fuel ratio will be off, the combustion temperature will be off, the oxygen sensor will report unexpected results, the ECU will throw a fault, and the engine won't run right. and there might be more carbon out the exhaust (into the cat) due to combustion being screwed up.
the big con of the EGR is that it dumps carbon into the intake. yuck. and they clog up with carbon themselves and cost way too much to replace.
and that's about all I know about EGR.
my post count is waaay lower than yours
the big con of the EGR is that it dumps carbon into the intake. yuck. and they clog up with carbon themselves and cost way too much to replace.
and that's about all I know about EGR.
my post count is waaay lower than yours
Good points.
But my point which is pondering me.....
My car ran fine with a pluged EGR, yet a lot of people have idle problems. So what I am thinking is that I can get around this with my E-manage somehow. See if I have a functioning EGR on the car, yet blocked between the EGR and manifold, I don't think I will have a CEL for insufficent flow. Therefore I would be able to control afr's durning idle with the E-manage.
OR
Have a breather on the EGR and chance having a lean condition due to the EGR opening during partial throttle and sucking in un-metered air.
But my point which is pondering me.....
My car ran fine with a pluged EGR, yet a lot of people have idle problems. So what I am thinking is that I can get around this with my E-manage somehow. See if I have a functioning EGR on the car, yet blocked between the EGR and manifold, I don't think I will have a CEL for insufficent flow. Therefore I would be able to control afr's durning idle with the E-manage.
OR
Have a breather on the EGR and chance having a lean condition due to the EGR opening during partial throttle and sucking in un-metered air.
people have idle problems when their EGR is stuck open (not closed).
idle is a delicate balance. the amounts of air and fuel are small, and there's no load to smooth the fluctuations. so the amount of exhaust gasses allowed in by a stuck open EGR is enough to screw up idle. same thing with a small vacuum leak.
at speed or under load, a stuck-open EGR valve will have less impact than at idle. egr would normally be open, and the amount of fuel and air are higher, lowering the impact of incorrect EGR position.
a stuck-closed EGR probably wouldn't affect idle because it would be closed anyway. but under load or at speed I'd expect problems. maybe just fuel economy and emissions, but I'd expect a CEL.
idle is a delicate balance. the amounts of air and fuel are small, and there's no load to smooth the fluctuations. so the amount of exhaust gasses allowed in by a stuck open EGR is enough to screw up idle. same thing with a small vacuum leak.
at speed or under load, a stuck-open EGR valve will have less impact than at idle. egr would normally be open, and the amount of fuel and air are higher, lowering the impact of incorrect EGR position.
a stuck-closed EGR probably wouldn't affect idle because it would be closed anyway. but under load or at speed I'd expect problems. maybe just fuel economy and emissions, but I'd expect a CEL.
Last edited:
IIRC, the EGR is supposed to remain closed at idle. The only place you'd notice differences in AFRs would be under load as mentioned. If you have some sort of engine or fuel management this won't be an issue obviously as you could tune around it but I still don't like the whole unmetered air thing. I'm really curious what the people planning on buying 505zoom's intake manifold plan on doing when there isn't an EGR port. You can drive around with the EGR CEL - it doesn't throw the car into limp mode or anything like a MAF or primary O2 related CEL.
Definitely let us know how that goes. No one has been able to answer my question of whether the EGR has to see "flow" or not. The people that get CELs are the ones that block off the port and leave the EGR in the stock location. I want to know if the EGR is relocated but still plugged in so the valve will still open and close if a CEL would be caused.
- :
- 2003.5 Laser Blue MSP
I plan on getting my EGR blocked off, and my IM and EM EGR tube blocked off as well. But for me i dont really care about the cell cause I have Microtech that throws a cel of its own.
But to answer the questions I think the EGR cel comes on when there isnt sufficient airflow. Now this is only a speculation because I remember reading it somewhere on here a while before but im not completely positive.
But to answer the questions I think the EGR cel comes on when there isnt sufficient airflow. Now this is only a speculation because I remember reading it somewhere on here a while before but im not completely positive.
just to be clear I'm not positive on anything I've said. I'm a software guy so wtf do I know about EGR and motors and s**t
I see it too but in my car it's a small device on the passenger side connected to a vacuum line from the intake manifold. I'm not completely certain as to how the entire system works but I don't see how blocking/moving the EGR valve will have any affect on the EGR boost sensor or EGR boost sensor solenoid valve.
purely speculating... I think the EGR boost sensor can sense the EGR valve opening. it's measuring pressure downstream of the valve, and opening the valve affects pressure in the manifold by connecting it to exhaust. I don't know if the ECU is looking for pressure pulses as the exhaust valves open/close, or just a pressure change when the EGR valve opens.
That sounds like a pretty good description. I have a 626 IM so I'm sure that system is all messed up with my current vac routing scheme. Either way, if the ECU is looking for a distict change in vacuum associated with the opening of the EGR any sort of movement/blockage will screw with the system and quite probably throw a CEL. It really does appear as if the only options are: leave the EGR where it is, get a standalone, or throw a CEL.
