[4ePikanini]

I deleted my EGR a while ago and have been following EGR threads for some time.

The pajero has a throttle flap that closes almost fully at idle (only at operating temp) and closes completely when shutting down the engine.



Reading a bit about EGR I suspect that the pajero uses PWM to partially close the throttle when EGR is activated to help draw in exhaust gasses.

With the EGR blanked less air/exhaust mixture enters the cylinders creating a rich mixture and possibly robbing some power.

I disconnected the vacuum diaphragms to test if it has more power this way at cruising speeds when the EGR will usually be activated.

See operation here - https://www.pajeroclub.co.za/forum/viewtopic.php?t=3035

It seems to feel more gutsy. But it would throw a CEL at idle (operating temp) as I suspect the Boost sensor picks up there is no vacuum.

So I T'd a vacuum hose from the idle diaphragm to the boost sensor (leaving the idle diaphragm disconnected, that will give the boost sensor a bit of vacuum at idle to fool it - it worked! No CEL at idle but the throttle flap is wide open.

I don't know if the engine kill diaphragm is the PWM (or if at all) so I simple just pulled the vacuum hose off that one (the downside is that I don't have an engine kill mechanism in case of engine runaway but I'll rewire that solenoid to get that functionality back.)

The car definitely feels like it has more oomph and time will tell if it helps my horrid fuel economy. I actually caught a fortuner D4D on the highway that was obviously gunning it by the looks of the exhaust fumes - whereas I struggled to catch a fortuner a few months ago - https://www.4x4community.co.za/forum/sh ... p?t=110922

I am still not sure if the Pajero's ECU uses PWM on of the throttle flap diaphragms for EGR but my mod has certainly given it some extra oomph.

[Nismo]

Hi Marius,

So does this mean when you disconnected the vaccum pipe the throttle butterfly stay open the whole time when at operating temprature?

[4ePikanini]

Hi Marius,

So does this mean when you disconnected the vaccum pipe the throttle butterfly stay open the whole time when at operating temprature?

Correct. If you simply disconnect the vacuum pipe you will get a CEL at idle when up to operating temp.

To avoid this take the idle diaphragm vacuum pipe and T-piece it into the boost sensor's hose.

Simply pull the vacuum hose off the engine kill diaphragm - it doesn't throw a CEL on mine but note that you won't have an engine kill mechanism in case of a diesel runaway, but I am going to rewire the engine kill solenoid to an ignition 12v that will restore that function.

NB : I don't know if the throttle plate is used as a restriction to aid EGR function but I suspect so as I am convinced the car now feels more responsive.

The extra air to the injected diesel should lower EGT as well

[Nismo]

I think mine stays open even if everything is plugged in.
That is why I changed the engine temp sensor.

I will try to post 'n vid of mine.

[4ePikanini]

I think mine stays open even if everything is plugged in.
That is why I changed the engine temp sensor.

I will try to post 'n vid of mine.

comparative videos.

Hot Idle and revving

[BBvideo 425,350]http://www.youtube.com/watch?v=fR4NC2vVH8U[/BBvideo]


Cold start and kill

[BBvideo 425,350]http://www.youtube.com/watch?v=EEvaIomD4Ow[/BBvideo]

[Rui_DID]

In my DID did the following:

I put a rubber spacer on the idle valve as seen in the photo.




So when the engine is at normal temperature and the idle valve closes, it does not close completely and therefore compensates the absence of EGR gases. This way also does not light up lights of engine malfunction.

Also the "switch off valve" continues to work normally.

Regards from Portugal

[4ePikanini]

The EGR is not activated at idle. I want extra airflow at driving speeds when the EGR is normally activated and (I suspect) the throttle plate is partially closed to assist in exhaust gas scavenging.

The other alternative is to keep the egr valve but route the piping into a boost pipe instead of the exhaust manifold.

[Bigwill]

A few points going through my mind given a situation where EGR is deleted:
1. Whenever the EGR is triggered the valve my close partially, but vacuum now draws pure air only. No exhaust gasses. This means a very rich oxygen mixture and therefore better combustion. This could offset the fear of over fueling.
2. The air from the intercooler going down the inlet manifold will be much cooler in the absence of hot exhaust gasses mixed into the inlet manifold. Again more dense air into the combustion chamber resulting in beter combustion. This could also work against the fear of over fueling.
3. The prevention of carbon buildup in the inlet tracks is obviously the main benefit; however I expect to get beter performance and economy.
Personally I don’t think there is much to worry about. Did the delete on my car today. Need some time to evaluate.

[4ePikanini]

A few points going through my mind given a situation where EGR is deleted:
1. Whenever the EGR is triggered the valve my close partially, but vacuum now draws pure air only. No exhaust gasses. This means a very rich oxygen mixture and therefore better combustion. This could offset the fear of over fueling.
2. The air from the intercooler going down the inlet manifold will be much cooler in the absence of hot exhaust gasses mixed into the inlet manifold. Again more dense air into the combustion chamber resulting in beter combustion. This could also work against the fear of over fueling.
3. The prevention of carbon buildup in the inlet tracks is obviously the main benefit; however I expect to get beter performance and economy.
Personally I don’t think there is much to worry about. Did the delete on my car today. Need some time to evaluate.

exactly my thoughts. Let us know if you do the mod or not and your fuel economy changes (if any)

[Bigwill]

I think mine stays open even if everything is plugged in.
That is why I changed the engine temp sensor.

I will try to post 'n vid of mine.

My observation this morning after a run of some 30 km (ie Normal temp.) with my EGR deleted showed up a discrepancy with what you are experiencing. I happen to have the same behaviour as Nismo. I am a little confused from your notes on the pictures you show, as I believe the top diaphragm operates the Kill valve only. If this is the kill valve then I’d expect it to stay open permanently until you turn the key off. That is what I experienced even with the engine at normal temp. Also Nismo has that. What the bottom diaphragm controls I can not see as yet. It may have something to do with the idling flow. Now I saw from your video that your kill valve does fluctuate when hot. Are you sure that is working correctly? Is your car not perhaps suffering from vacuum starvation when hot? Could this explain your consumption problem?