Will Blocking the EGR affect valve life

[maysy1]

Hey Gurus
I have recently blocked the egr and have fitted a 2.5" mandrel bent exhaust going into a 3.0" high flow system. I have also adjusted boost acoordingly. So it is now, what it was before. Now I dont know if I am hearing things but my inlet and exhaust valves seem to be making more noise? Is this possible as a result of the egr being blocked? Or does the design of the engine make this an impossiblitity? I would appreciate your thoughts as I am about 1 day from reversing the blocked egr? Thanks Gurus. As you can see from my signature I have a 2003 3.0l AUTO Patrol.

[hhl]

The noise you hear is probably increased combustion noise, not valve lifter noise. That does happen when you block the EGR system, you will mostly notice it under light load (when the EGR valve is normally open). Simply put, there is now a higher percentage of oxygen in the cylinder than there would be if the mixture included some exhaust gas. This tends to produce a bit more "diesel clatter". I don't believe it does any harm, bear in mind that under higher engine loads there is no EGR flow anyway, blocked or not.

[maysy1]

HHL,
thanks for your thoughts I feel a bit easier now I understand the process. I was only a bit alarmed because there was chatter on another site regarding valve issues on blocking the egr. Normally I prefer to only get my information on this site as the members here know these vehicles well and in my opinion have a great mechanical depth. I have been in the game myself but know when to ask those that know more. Thanks again!

[baron]

Gday hhl.
Does what you mentioned above apply to a TD42I as well. Why I'm asking is, I have a noise that sounds like lifters or tappets and this also happened after the EGR was blocked. It only occurs from idle to about 1200 rpm, it also only does it when hot, I thought at first something more sinister happened to the engine after the upgrade. The noise sounds worse on the drivers side when listening through the wheel arch. I had been looking for the source of this noise for weeks with no luck, I hope your right about where its coming from. Cheers.

[Chaz]

I agree with hhl. Consider that before Euro3, no diesels even had EGR. EGR only decreases the efficiency of a diesel, and having all that abrassive exhaust gas flowing through the valves can't be good for them or their seats.

[tweak'e]

Originally Posted by Chaz

I agree with hhl. Consider that before Euro3, no diesels even had EGR. EGR only decreases the efficiency of a diesel, and having all that abrassive exhaust gas flowing through the valves can't be good for them or their seats.

interesting you say that.

had the other day someone who partly blocked off EGR on a CRD vehicle (some euro car) and fuel economy went worse (so he says).
also had someone with a navara (tho i think it was his poor air intake) and a few odd older vehicles. all got worse economy with EGR blocked off.

trouble is fuel usage is not an easy thing to calculate and not many do it very well.

a thought here was that due to most jap manufactures running tiny turbo's that the extra gas flow put the turbo onto a less efficient part of the turbo's map. ie EGR bleeds off exhaust gas and thats compensated by the turbo being more efficient.
really rough idea at the moment.

maybe with modern diesels we need to block EGR and change the whole turbo to suit ??

the other thought was that with EGR injection timing is advanced due to the ignition delay EGR makes. block off EGR and injection timing now is to far advanced.

[dqnuke]

Originally Posted by maysy1

Hey Gurus
I have recently blocked the egr and have fitted a 2.5" mandrel bent exhaust going into a 3.0" high flow system. I have also adjusted boost acoordingly. So it is now, what it was before. Now I dont know if I am hearing things but my inlet and exhaust valves seem to be making more noise? Is this possible as a result of the egr being blocked? Or does the design of the engine make this an impossiblitity? I would appreciate your thoughts as I am about 1 day from reversing the blocked egr? Thanks Gurus. As you can see from my signature I have a 2003 3.0l AUTO Patrol.

I know this has already been discused but, can not that sound come from the inlet butterfly??

As the ecu is trying to put de vehicule in egr mode but does not recive any flow variation signal (a decrease) from the MAF. It is still trying (the ecu) to, somehow, close the inlet butterfly to force aire through the egr....

To me it is difficult to understand that you can hear a clatter when the car is cruissing.......

[trev zd30]

Originally Posted by tweak'e

interesting you say that.

had the other day someone who partly blocked off EGR on a CRD vehicle (some euro car) and fuel economy went worse (so he says).
also had someone with a navara (tho i think it was his poor air intake) and a few odd older vehicles. all got worse economy with EGR blocked off.

trouble is fuel usage is not an easy thing to calculate and not many do it very well.

a thought here was that due to most jap manufactures running tiny turbo's that the extra gas flow put the turbo onto a less efficient part of the turbo's map. ie EGR bleeds off exhaust gas and thats compensated by the turbo being more efficient.
really rough idea at the moment.

maybe with modern diesels we need to block EGR and change the whole turbo to suit ??

the other thought was that with EGR injection timing is advanced due to the ignition delay EGR makes. block off EGR and injection timing now is to far advanced.

Some interesting points brought up there tweak'e. Do u know which model vehicles the injection timing is advanced on during EGR?


Trev

[hhl]

I agree with Tweak'e. The injection timing which is set for egr would be the cause, however, I doubt whether it has any other detrimental effect. As for the 4.2 (and 2., it is a totally different EGR system in that one and I would say the EGR valve is probably only open at idle. This can be verified by looking at the butterfly valve. It opens as soon as you increase rpm off idle. The butterfly valve on the ZD30 is purely there to choke airflow at shutdown, it has nothing to do with the EGR system.

[Chaz]

Originally Posted by trev zd30

Some interesting points brought up there tweak'e. Do u know which model vehicles the injection timing is advanced on during EGR?


Trev

I could be completely wrong here, but when we were setting up Nistune we could not find an ECU register for injection timing, which leads me to believe that it may be a mechanical thing in the IP. The only register that we could interrogate was for injection duration, which tends to increase with rpm and tps and is fairly linear.

[Chaz]

Originally Posted by tweak'e

had the other day someone who partly blocked off EGR on a CRD vehicle (some euro car) and fuel economy went worse (so he says).
also had someone with a navara (tho i think it was his poor air intake) and a few odd older vehicles. all got worse economy with EGR blocked off.

I’d be curious to know if these were all waste gate turbo cars. One issue is that they do become inefficient because there isn’t any control over the waste gate like a VNT. The VNT can be controlled to reduce boost for EGR, but a waste gated turbo needs to have the butterfly valve partially close to restrict boost, but that doesn’t stop the turbo from creating boost, hence very inefficient.

[tweak'e]

I’d be curious to know if these were all waste gate turbo cars

yes and no. some where, some are not.
you reckon wastegate creep could be causing some loss in efficiency? the extra increase in boost is opening the waste gate slightly.

I could be completely wrong here, but when we were setting up Nistune we could not find an ECU register for injection timing, which leads me to believe that it may be a mechanical thing in the IP.

i wonder if its done solely by the IP ECU in the pump itself?
TD42i would be done by the main ECU

Do u know which model vehicles the injection timing is advanced on during EGR?

absolutly no idea
you would have to crack ECU or simply read what the injection timing does when EGR kicks on/off.

[maysy1]

This is why I love this forum. Sometimes I love shutting the mouth and opening the ears. Thanks for the wisdom guys appreciate it. I will just leave my egr blocked and soon as the dawes arrives I will run the manual set-up as per Chaz's and Whitie's schematics.

[hhl]

Chaz,
I don't believe the ECU actually reduces boost as such for EGR to happen, it actually increases it by pulling the lever on the turbo to create more backpressure and hence more boost. This happens at around 80 to 100 clicks with light throttle and that is also the reason why the turbo may overboost after the EGR is blocked.
In a truck where the EGR operates normally, the boost will spike as the turbo is still in the max boost position when you plant your foot but the EGR valve will shut and all the exhaust gas goes through the turbo.
Have you monitored the vacuum line on the actuator to see what happens under different conditions?
I wonder how much "pulse width" modulation happens or whether the lever is either hard on or off. I know it modulates when the engine is cold, but don't know what it does after it is warmed up.

[Chaz]

Originally Posted by hhl

Chaz,
I don't believe the ECU actually reduces boost as such for EGR to happen, it actually increases it by pulling the lever on the turbo to create more backpressure and hence more boost. This happens at around 80 to 100 clicks with light throttle and that is also the reason why the turbo may overboost after the EGR is blocked.
In a truck where the EGR operates normally, the boost will spike as the turbo is still in the max boost position when you plant your foot but the EGR valve will shut and all the exhaust gas goes through the turbo.
Have you monitored the vacuum line on the actuator to see what happens under different conditions?
I wonder how much "pulse width" modulation happens or whether the lever is either hard on or off. I know it modulates when the engine is cold, but don't know what it does after it is warmed up.

Hi hhl,

I completely agree with you about the VNT increasing boost to raise back pressure to enhance EGR under most conditions other than for maximum EGR. As we know, EGR is present almost all the time except for full throttle and low or high engine temps. Under most conditions when low levels of EGR are required, this is the method used to achieve it, but my concern has always been when maximum EGR is delivered.

It’s very hard in our case to monitor the EGR valve’s operation, as it has a few varying positions in relation to TPS and engine speed. It is much easier to monitor the vacuum signal to the turbo actuator. Once warm, the actuator holds up firm and stays there depending on TPS and engine speed or until the intake air pressure sensor cuts the signal. At light throttle or light loads, the turbo doesn’t normally over boost and this is when we have maximum EGR. The actuator and its control react directly to TPS, but at cruising speeds (low load) boost drops without any TPS input. There have been many reported cases of this and I’ve seen it on 3 Di Patrols that were all running perfectly.

In cases of non VNT equipped late model turbo diesels with EGR, they all have a throttle plate or control valve fitted into the inlet duct which closes for maximum EGR. This is necessary to reduce intake air volume which enhances EGR. The ZD30’s VNT can be controlled via the ECU and it’s control solenoid, so it doesn’t need a throttle control valve to reduce boost.

This is an extract from the RD28 manual which uses a throttle valve to reduce intake air and increase EGR. You can clearly see that at normal operating temperature and light load, maximum EGR is achieved by opening both EGR control valves and it is the only time that the throttle valve closes to achieve maximum EGR gas flow.



This method of operation is different to a ZD30, but the principals are the same. To increase EGR or obtain maximum EGR, you must reduce boost or intake air volume.

[tweak'e]

Originally Posted by Chaz

To increase EGR or obtain maximum EGR, you must reduce boost or intake air volume.[/FONT]

most VNT do it by increaseing back pressure so its above boost pressure. air volume is reduce by egr displacing the air.

interesting the non-crd ZD30 also uses a butterfly to increase EGR, the swirl control valve.

[Chaz]

Originally Posted by tweak'e

most VNT do it by increaseing back pressure so its above boost pressure. air volume is reduce by egr displacing the air.

interesting the non-crd ZD30 also uses a butterfly to increase EGR, the swirl control valve.

I agree, but consider that there are a few levels of EGR on a ZD30 and this is one of them. I’m not sure that the swirl control valve has anything to do with EGR. It opens at part throttle and remains open all of the time above 1250rpm.

[Skiman]

Originally Posted by tweak'e

interesting the non-crd ZD30 also uses a butterfly to increase EGR, the swirl control valve.

I put a vac gauge on the swirl valve actuator line to see when it was in operation, as far as I could tell, it only opened when the car was idling (under 1200 rpm)with the car in gear(manual 05). And only once the engine warmed up.
So I do agree that the swirl is there for egr, but only in the above conditions, say at stop lights etc.

[Chaz]

Originally Posted by Skiman

I put a vac gauge on the swirl valve actuator line to see when it was in operation, as far as I could tell, it only opened when the car was idling (under 1200 rpm)with the car in gear(manual 05). And only once the engine warmed up.
So I do agree that the swirl is there for egr, but only in the above conditions, say at stop lights etc.

This is from the ZD30 manual.......

"This system has a swirl control valve in the throttle body.
While idling and during low engine speed operation, the swirl
control valve closes. Thus the velocity of the air in the intake
passage increases, promoting the vaporization of the fuel and
producing a swirl in the combustion chamber.
Because of this operation, this system tends to increase the
burning speed of the gas mixture, improve fuel consumption, and
increase the stability in running conditions.
Also, except when idling and during low engine speed operation,
this system opens the swirl control valve. In this condition, this
system tends to increase power by improving intake efficiency
via reduction of intake flow resistance, intake flow.
The solenoid valve controls swirl control valve’s shut/open condition.
This solenoid valve is operated by the ECM."


The swirl control solenoid is energized (on) to close the valve. Also, if you tested it in neutral, it will always be open.

[Pitbull]

Originally Posted by Chaz

This is from the ZD30 manual.......

"This system has a swirl control valve in the throttle body.
While idling and during low engine speed operation, the swirl
control valve closes. Thus the velocity of the air in the intake
passage increases, promoting the vaporization of the fuel and
producing a swirl in the combustion chamber.
Because of this operation, this system tends to increase the
burning speed of the gas mixture, improve fuel consumption, and
increase the stability in running conditions.
Also, except when idling and during low engine speed operation,
this system opens the swirl control valve. In this condition, this
system tends to increase power by improving intake efficiency
via reduction of intake flow resistance, intake flow.
The solenoid valve controls swirl control valve’s shut/open condition.
This solenoid valve is operated by the ECM."


The swirl control solenoid is energized (on) to close the valve. Also, if you tested it in neutral, it will always be open.

Chaz
Im not familiar with the technical operation of the ZD30 although i find what you guys submit about it quite interesting , if the above information about a swirl control valve in the throttle body that promotes vaporisation in the combustion chamber is correct , then it resembles that of a Hiclone which we regularly have a laugh and joke about that it doesnt work , yet engines come out factory fitted with such devises by the sounds of it .
Im not a Hiclone sympathiser but WTF