Exhaust Gas Recirculation System

Clark's son · June 29, 2012

Our Mitsubishi Montero sport 2007 4D56 turbo intercooler diesel has developed an EGR related problem.

When it is happening it has very low power from 1500-3500rpm and a lot of smoke and a deafening sound.

The mechanic pointed out that it stopped when the coolant sensor or the tube that went to the system was removed,

so he said that it was a defect of the coolant sensor or a sensor near the unit.

My opinion was that the EGR needed a little bit of cleaning.

This has run more than 130 000km and was used to sip normal diesel.

Noticed the fuel economy drop from about 12kmpl to 7kmpl.

Now i brought it home with a tube removed, thus bypassing the EGR

Is it good to run bypassing the EGR,

From the internet I found that it was involved mainly in reducing NOx emmisions and slightly reduce performance and economy in diesels

So as Sri lankan emmision tests only measure opacity

Am I better off without it

I hope an expert will shed some light into this problem.

Edited June 29, 2012 by Clark's son

NZer · June 30, 2012

Does this make a huge tak tak tak sound when trying to accelerate? If so this is an issue with the injector pump and injectors and quite common when they need servicing. Make sure you service the Injector pump and also the injectors. At the same time make sure you change timing belt along with the balancer belt. Wrong ignition timing can also lead to loss of power and smoke. Also when the timing belt gets a bit old it tends to jump a tooth or two causing timing to change. My best advice is check timing and replace the two belts for a start. If you need more info ask me and ill help.

Clark's son · June 30, 2012

Thank you very much NZer

Yes the noise is a huge tuk tuk like sound.

Checked the injectors and the 2 timing belt and they where ok.

Didn't dismental the pump as everyone told it was too young to be serviced, and that the original sound of the vehicle would change afterwords.

IMO as it becomes normal when the components related to the EGR is removed it couldn't be the pump isn't it.

BTW The mechanic judged the condition of the timing belt by the looks of it could it still be sliping while it looks good.

It is a genuine kit replaced around 75 000km ago

NZer · June 30, 2012

Timing can affect it at different speeds. This is usually very common on 4D56T engines and what you will face is a stuffed cylinder if you dont attend to it soon. Whats causing this is excess diesel on cylinders. This will eventually cause your piston to melt inside the cylinder blowing the engine. Usually the culprit is a faulty injector, injector pump or jumped tooth. In this case first start off by checking the belt timing, Make sure the pully bush is still in tact cos its common for it to break and slip timing. Then check the balancer belt which is inside. Your mechanic cant see this unless he takes of some parts. Then if this fails remove and check injectors. My feeling is that one injector is dripping instead of spraying the fuel. Try and see. If you sort this then everything else will fall into place.

Clark's son · June 30, 2012

Timing can affect it at different speeds. This is usually very common on 4D56T engines and what you will face is a stuffed cylinder if you dont attend to it soon. Whats causing this is excess diesel on cylinders. This will eventually cause your piston to melt inside the cylinder blowing the engine. Usually the culprit is a faulty injector, injector pump or jumped tooth. In this case first start off by checking the belt timing, Make sure the pully bush is still in tact cos its common for it to break and slip timing. Then check the balancer belt which is inside. Your mechanic cant see this unless he takes of some parts. Then if this fails remove and check injectors. My feeling is that one injector is dripping instead of spraying the fuel. Try and see. If you sort this then everything else will fall into place.

Thank you very much.

The injectors were cleaned,

The 2 timing belts were checked and the problem is absent when the coolant sensor or lines related to the EGR is removed.

Took it to a new mechanic as the 1st seem to be not confident enough,

Will tell him to completely remove and check the timing belts too.

The 2nd mechanic told that the EGR needed cleaning and it would take 2-3 days at the garage,

Is this true, will it take that much time, he also mentioned that the turbo also may have been clogged.

NZer · July 1, 2012

Lol im not sure what you mean by the turbo getting clogged as this item cant get clogged. It can get weak and stuff but not clogged. It does how ever have an oil line through it but since you have maintained it well it shouldnt be a problem. I still feel the issue is with your injectors. May be the last person who did it hasnt done a decent job. Im also not talking about cleaning injectors, im actually talking about removing them and re-pressurizing them so that they have optimum spray.All my life i have done these 4D56 engines but never seen one that has an EGR issue that causes this kata kata kata noise. The only thing that ever caused this was faulty injector causing detonation in the piston cylinder due to it dripping diesel and not spraying it. So i advice you to check this before anything. I dont think it will cost you a ton to remove the injectors and to re-pressurize and re install. Plus 50,000 since your last service is a lot of distance for a pajero injector as they have the tendency to screw up fast.

Shehan_WCC · July 2, 2012

You probably bypassed the EGR control solenoid or vacuum actuator but in some models the turbo actuators as well as other systems are kept close by and they all look the same ,maybe you bypassed the turbo pressure solenoid .In some euro cars if this doesn't work or is clogged the vehicle fails to accelerate properly and in proportionate to acceleration