Anyone got an egr valve I can butcher?

[Lewd Lux Lover]

Hi, can anyone help with a little experiment? Mainly for people who have deleted their EGR valve, removed it and still have it sat on a shelf gathering dust.

Research shows that deletion of the EGR, while cleaning up the engines combustion cycle, causes raised EGT's. In the 1kz surf anyway.
This is due to the restriction caused by the big butterfly in the throttle body.

It is there to provide a safety shut off in the case of runaway but also to give some vacuum for the EGR to suck in from the exhaust. (The EGR port sits just below the butterfly).
The engine expects to see a certain amount (volume) of mixed air and exhaust gasses for the combustion cycle. By blanking the intake side of the EGR and not removing the butterfly you are preventing the correct volume of gasses entering the chamber. There is oxygen to burn in the exhaust gasses going in after all and the engine has no way to feed back this kind of unbalance because there is no O2 sensor in the system. No negative feedback at all in fact.

Problem with deleting the EGR is that this butterfly is then still causing a restriction in the intake. Causing a vacuum for a system no longer active. Result seems to be raised EGT's due to a lower volume of air/gasses available to the combustion cycle.
Thats the known effect people speak about. You can extrapolate other negative effects from that like engine wear, hot spots on pistons and reduced efficiency.

My thought is this:

Rather than delete the EGR valve with a couple of plates and a ballbearing why not reroute it and feed it cold air? Blank the exhaust side and either plumb the EGR pipe into the airbox or stick a decent breather filter on the end of it? This is just an idea I want some opinion on. Not something I know has or can be done..


Prospective result? Engine gets the volume of air it expects to get, the restriction of the butterfly is negated and your combustion cycle is now cleaner and fully loaded with air.

Result of that? Throttle response increased, lower EGT's and possibly better mpg?

So. I deleted mine ages ago and chucked the bits.... Since then I have an EGT gauge fitted and fancy testing this hypothesis out.
With real world readings I can see if its a valid modification or not.

I need the EGR bits from a factory intercooled 1KZ, or any 1KZ to bolt back on and feed cold air instead of exhaust gasses. I will then compare readings from the EGT gauge and maybe a couple of dyno runs as I live two miniutes away from powerstation in tewkes.

Now normally I would say deleting the EGR was enough. Stop at that point. But the surf engine has two sides to the EGR and without addressing the side effects caused by ignoring the other side I think we might be suffering for it.

Anyone got an EGR for scooby snacks and thanks so I can test this idea out?

And does anyone have an opinion on this? Is it sound or am I barking?

[shokenore]

Some barking but maybe only at the full moon.

Egr is to recirc some exhaust gas to lower combustion temps to a point where less NOx is produced.

The extra heat produced is due to a more complete combustion of the fuel/air mix not being diluted by exhaust gas.

I very much doubt there is much usuable O2 left to aide in combustion.

Feeding this exhaust bypass into the air box would make the situation worse than having the OEM egr plumbing.
All that lovely hot exhaust gas hitting the clean air side of the turbo....

The ideal solution would be to tune the fuel pump to give optimum burn and a safe EGT ( with the egr deleted/blanked) this coupled with a intercooler and or a less restrictive exhaust.


btw do you now how many times I misspelled exhasut

[budweiser]

got one if you want to play with it.

[tweak'e]

And does anyone have an opinion on this? Is it sound or am I barking?

barking madd

the butterfly lowers the air pressure. its not necessarily vacuum.
if you did what you suggest then boost pressure would go back up the egr valve into the airbox.
you would end up with even less air in the combustion.

blocking egr doesn't raise EGT's.
where that theory comes from is EGR reduces PEAK combustion temps. so blocking egr increases peak temps, ie returns it back to normal.
with hot egr systems that the 1kz has, the cold air is being replaced by hot gasses. the reduction in cooling means the average temp goes up which is seen as higher EGT's.

the problem with blocking the egr, is the butterfly is blocking airflow and no egr is going in to replace that air.
so you have a reduced amount of gas in the cylinder which gives a lower effective compression. that can cause combustion problems especially on worn engines that have lowish compression and worn injectors. combined with lack of heat due to lack of egr it can cause injection problems to the point of blowing white smoke.

easiest solution is to get rid of the butterflies in the intake.
2nd would be to connect egr tube to the turbo side of the butterfly.
best would be fit a different butterfly and rig it to operate only at shutdown. (like 2lt engine)

[Lewd Lux Lover]

@snorkenore: Fair points all. I am unsure if you got the idea I had though as this sentence seems out of place:

''Feeding this exhaust bypass into the air box would make the situation worse than having the OEM egr plumbing.
All that lovely hot exhaust gas hitting the clean air side of the turbo....''

The whole measure of this is to totally REMOVE all exhaust gasses from combustion but at the same time, not restrict the intake but allowing to get cold air from somewhere. Can you fill out this sentence so I understand what you mean? There would be no exhaust gasses getting into anywhere in my idea.

@budweiser: sound mate, I'll give you a PM

@tweak'd: Ok so I should have said lower air pressure but you know what I mean. I do think you're onto something with the pressure equalising through the box though. That would be the path of least resistance. It would work on an NA engine though.. But you see the issue. Two sides to the system, disable one and the other affects normal operation detrementally.
I think you have the measure of it with a plumbed pipe into the turbo side. That has legs to run. A bypass to the butterfly. When the valve opens it gets pressurised air from the turbo rather than open air or the exhaust.. Nice.
Taking out the butterfly seems to be the simple solution but you then can suffer a total runaway with no protection. As the missis drives it I want that left in as safety. lol..
Unfortunatly the system on the intercooled 1kz is different again from the 1kz and further away from the 2lt. Not sure if that possible.

Thanks for your ideas and comments guys. Very informative. I will be moving on with this experiment but will be considering plumbing the pipe just above the butterfly in the intake path..

Cheers, I will report when I have readings and results.

[shokenore]

I got the idea from this


"My thought is this:

Rather than delete the EGR valve with a couple of plates and a ballbearing why not reroute it and feed it cold air? Blank the exhaust side and either plumb the EGR pipe into the airbox or stick a decent breather filter on the end of it? This is just an idea I want some opinion on. Not something I know has or can be done.."


The best way to increase cold air to the combustion cycle would be to have it turboed and intercooled.

I do want you to post more of this plan but and with the greatest of respect I do think you are trying to invent the wheel.
PS shokenore as in shock and awe as in brand new xBox and a shiny new copy of Halo and needing a xBox gamertag.

[Lewd Lux Lover]

I think you missed ''Blank the exhaust side'' just before the comment you picked out.


As I said to someone else who used the same excuse recently... We started off with stone circles with holes in the middle and we now have forged formula 1 wheels. plus its a good way to fill a sunday afternoon tinkering in the garage.....

[Lewd Lux Lover]

@Budweiser: I cant send you a message mate. I dont have the privilages.

[tweak'e]

Unfortunatly the system on the intercooled 1kz is different again from the 1kz and further away from the 2lt. Not sure if that possible.

pull the stock butterflies out.
find an aftermarket or even stock butterfly (eg petrol engine) thats big enough.
fit it somewhere between turbo and intake (before IC ?) and then rig the stock vsv and actuator so it closes on shutdown.

or seal small butterfly shut, remove throttle cable and rig actuator and vsv to operate big butterfly.
rig throttle cable to operate TPS in new location.

[Lewd Lux Lover]

Now those are tinkerable ideas!

I will start with some readings with it blanked, then rig the EGR into the intake path, take some readings and continue.

The object to see if any combo lowers average EGT or offers any 'butt dyno' noticable difference.

There was a serious drop in I/T temps and it came onto boost faster after I tinkered with the PCV setup so I think this is worth looking at. I now sometimes get post intercooler temps LOWER than the temp in the air box, generally when around town when you need that cold air for junction escapes and keeping up with traffic. Well worth the sunday afternoons or whatever time I can find..

Next major project is remove the pump correction resistors, replace with variables pots, and tune it up on a rolling road. But I want a clear air path first.

[budweiser]

email me then

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[Lewd Lux Lover]

Nice one.

[Gra1986]

Very interested to see the out come with this!!

[tweak'e]

Now those are tinkerable ideas!

I will start with some readings with it blanked, then rig the EGR into the intake path, take some readings and continue.

The object to see if any combo lowers average EGT or offers any 'butt dyno' noticable difference.

There was a serious drop in I/T temps and it came onto boost faster after I tinkered with the PCV setup so I think this is worth looking at. I now sometimes get post intercooler temps LOWER than the temp in the air box, generally when around town when you need that cold air for junction escapes and keeping up with traffic. Well worth the sunday afternoons or whatever time I can find..

Next major project is remove the pump correction resistors, replace with variables pots, and tune it up on a rolling road. But I want a clear air path first.

i do like it when people actually take readings. far better than a butt dyno.
but just watch the sensors don't get effected by other things. eg your airbox sensor is being heated by other means, its probably not reading true intake temps or your sucking in underbonnet air. fixing that would help a lot.

[Lewd Lux Lover]

Yeah its difficult to know where to put things like that for sure.
I went with right next to the OE temp sensor in the I/C for the post turbo because I hoped yota did their homework on that one and inside the airbox on the clean side resting in free air. Neither of those will be affected by this mod though I'm thinking. Mainly as it will be after both of them in the chain. The EGT sensor will be the one to watch and that is mounted in the top of the manifold where the runners converge and go down to the turbo.

So far I am thinking I will replace the short section of hose between the I/C and the T/B with one of thos funky samco ones with the side pipe built in. Then hardpipe that end onto the end of the EGR that normally sucks exhaust.
Then, whenever the engine opens the EGR valve it will be getting fresh compressed intake air from just above the butterfly rather than exhaust gasses or a brick wall of a deletion from just below it.


Now, reading an old thread, one you were in tweak'd, nifty nev seems to think the EGR is ONLY open while at idle and at no other time. You disagreed with him.
It would seem rather odd, from what I know of EGR systems, to only have it operate at idle. What with that being a very small % of its runtime and not the main time the engine will produce NOX
Only issue being if this is true it will bypass the smooth shutoff valve and nothing else. If thats the only time the EGR is open.
Honestly though, having seen the gunk that builds up in the intake, all that cant just be from sitting at idle......