Totally confused about the Alfa 159 JTDm EGR valve
Having read many posts on the topic of the beloved EGR valve on the JTDm Alfas, I now sit here totally confused whether it is a good or a bad thing to (in any number of ways) 'delete' the EGR from the system.
My own experience of blanking off my EGR valve with a solid plate has been to totally eradicate the annoying engine hesitation that plagued my car from the first 2500 miles onwards. Despite replacing it under warranty or removing and cleaning it myself, any hesitation that initially seemed cured, within some weeks, would return. It totally ruined my first 25,000 miles of 159 driving experience. But emboldened by the various Alfa forum threads discussing the EGR, I purchased a blanking plate on eBay, fitted the plate myself, and instantly the car drove more smoothly and the hesitation has never returned. That's the good side of the story.
The bad and/or confusing side of the story is the very mixed messages I read about what blanking the EGR actually does to the car's performance; and by that I mainly mean acceleration and pick-up; I'm less bothered about MPGs (although they are rubbish as well). I don't ever remember my 2.4 JTDm being a rocket but I would certainly claim that my current perception of my car's low down power (under 2000 rpm) is verging on pathetic. Pathetic for a 2.4 engine anyway. My wife's 1.9 diesel VW Touran is faster off the line than my Alfa. That's embarrassing. I was not considering whether it might be the EGR when I cleaned my MAP sensor and replaced my MAF sensor (expensive) as many said could potentially be the cause of poor low down performance. After all, why should I think it's the EGR when so many people said it improved performance (not just removed hesitation) and many, many forums for other makes of diesel, wax lyrical about the benefits of removing the EGR valve. And considering the mess they allow to be thrown back into the inlet manifold, who can blame them.
But then I read the following comment on the Alfa Workshop website about a stuck EGR: "...all the air pressure that is provided by the turbo charger is simply bled off into the exhaust system. This gives quite a distinctive driving fault which means that the power will only come in over 3000 rpm when the amount of air the turbo can compress exceeds the amount of air that can be bled out of the inlet manifold and so you get quite a power hike as you go through 3000 rpm." That sounds kind of intriguing. Nowhere else has said much about EGR positive effects except to reduce NOx emissions.
Then I read on the forum that you should really have your "EGR delete" done via the ECU. Yes, I understand this would hopefully prevent the Engine Warning Fault on my dashboard, but does that do something else more mysterious to the injection or general behaviour of the engine as well?
So, please, please, please could someone kindly cut through all the hype and tell me whether it is better to:
a) Leave the EGR blanked (as mind is now) because poor low down performance is bound to be due to something else
b) Leave the EGR blanked but get an EGR delete from the ECU because without this the engine will not run properly, or
c) Put back that horrible EGR valve (unblanked), clean it regularly, and hope the performance improvement overcomes the hesitations and the worry what other damage is going on inside the inlet manifold.