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Discussion Starter · #1 ·
I am looking to buy a sub 65k, diesel Brera or 159 Sportwagon, Lusso spec, preferably with roof rails, bluetooth, xenons and FSH. This is to replace my S4 Avant.

Whilst there are few out there (eBay, AT etc) why have so many of them had the def removed? With the new regs, there is no way that I (personally) would be comfortable buying something that is an automatic MOT fail.

I suppose my question is 'why do people do this mod', given the issues it causes when selling cars on.

Anyway, if anyone knows of a vehicle, please PM me.
 

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It's not always noticeable to the MOT examiner that the DPF has been removed, so it would pass a test without it.

There are countless, what I mean is shiete loads, of threads on here as to why and how the DPF, Egr, blah blah blah are removed, blocked, plugged and tampered with.

And another is spawned:lol:
 

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I wouldn't say its just an Alfa thing removing DPF's nor an automatic fail if one was. I often look at a tuning companies page on Facebook to see what they have remapped that week and they have cars of every make and varying ages weekly having DPF's err... amended shall we say.
 

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I wouldn't say its just an Alfa thing removing DPF's nor an automatic fail if one was.
It is an automatic MOT failure if the examiner notices it missing and is doing the test properly (ie not passing a car for a mate that would normally fail...).

But no, it isn't just an Alfa thing.
 

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Most of them would of had the dpf removed before the change or clarifying of the rules about if they should still have them fitted. Combined with a good remap the car will pass the mot emission test, which is just a calibrated smoke test not really an emission test so if the dpf has been holowed out rather than removed and replaced with a straight pipe it will probably pass an mot.

The goverment has recently anounced a clamp down on companies offering dpf removals especially if they are also an mot testing station

But to answer your question about why they are removed, they are quite restrictive so reduce power and increase fuel consumption and also unless the car is used for regular longish journeys they can block up and cause problems.
 

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As Jon 156veloce mentions they really don't work well on cars that do any short journeys, they pump up fuel consumption (regen literally involves pumps diesel down the exhaust), and they have a finite life before needing replacing (around 80-130k miles), and become more restrictive over time
The MOT test is a visual inspection, so if the DPF has been removed, then it will fail, many people simply take the insides of the DPF out, and the inspector will see the DPF in situ. The cars almost all pass the actual smoke test, it'll fail if there is something wrong with the engine or a bad power map has been given.
 

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Well they pass the test because it's set to a very high level. The long and the short of it is they pollute. Those of us with asthma will be delighted when the test finds the vehicles pumping out the fine particles.
 

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DPF's were required to be fitted to cars before the technology was fully developed due to pollution regulations

Arguably it still has some way to go, but the later generation of close coupled DPF's are much better than the ones miles away from the turbo.

Unfortunately the 1.9 and 2.4 diesels got the latter, and that is why they cause issues.

The 2.0 is better, but I am sure they will still cause issues at some stage as the miles mount up.
 

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It is an automatic MOT failure if the examiner notices it missing and is doing the test properly (ie not passing a car for a mate that would normally fail...).

But no, it isn't just an Alfa thing.
Agree David... I didn't explain that very well. As the test is visual I was thinking if the original dpf had been cored/drilled and not replaced with a straight pipe would the average MOT station pick it up?

I don't know why Alfa just didn't borrow the system Peugeot use as the associated costs in engine oil contamination, extra diesel consumption and extra wear/tear and miles put on the car to make sure it regens properly is silly. In two and a half years of mainly city commuting I honestly don't recall noticing my 407, which was remapped, ever going through a regen cycle. My Alfa... well every roughly 5 days now and 3 warnings about a clogged dpf.
 

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Couldn't help notice your original post on what car your swapping for an Alfa. You'll need a 2.4 with a decent map and then you'll struggle to get close to an S4. We had both in the family a while back, in 4th gear at full beans on open road my old ti (with f1 map) could just about keep the S4 honest but even then only just about hanging on. In all other areas the s4 destroyed the 159, except in the looks department obviously!!
 

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Discussion Starter · #11 ·
Couldn't help notice your original post on what car your swapping for an Alfa. You'll need a 2.4 with a decent map and then you'll struggle to get close to an S4. We had both in the family a while back, in 4th gear at full beans on open road my old ti (with f1 map) could just about keep the S4 honest but even then only just about hanging on. In all other areas the s4 destroyed the 159, except in the looks department obviously!!
It's not about a like for like power, I know there is no way I can get a FWD diesel to behave a like a V8 AWD ;-). These days I am more into bikes for fun and cars for practicality.

I'm looking to change because I just need something cheap and economical for motorway cruising (that looks nicer). I have owned several Alfa's in the past and fancy going back to the marque. BMW and Audi have been great, but I like the styling of the Sportwagon.

Regarding the DPF, it does not seem worth the effort to remove it. I haven't yet found a post (any marque) where some one has measured the performance results (on a dyno) before and after removing the DPF. It all seems to be anecdotal.
 

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Fair comment re the performance. And I know what you mean re the difference with a dyno before and after. Mine was night and day drive wise pre and post remap / dpf removal.
I must admit since I've sold her though I no longer have to go through that pre mot twitchiness re smoke test and dpf missing, and I don't miss that at all!
 

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Regarding the DPF, it does not seem worth the effort to remove it. I haven't yet found a post (any marque) where some one has measured the performance results (on a dyno) before and after removing the DPF. It all seems to be anecdotal.
Depends on why you remove it. If you remove for power gains, then obviously this needs to backed-up on a dyno. But, if you remove for driveability, fuel consumption and reliability then anecdotal evidence is all you'll get.

My average journey is a 4 mile round-trip that I do daily. Before removing the DPF my Brera ran like a choked pig. Until it got to 2000 revs there was no discernible torque, it was hit-and-miss whether or not it would start 1st time or 5th time, I couldn't even take it up a decent hill at 40 in 4th. Every week or so I'd get a warning light and limp mode that would only be cured by a good thrashing (not a hardship, but not good for the fuel consumption either). I was averaging just over 25mpg.

Now I've removed the DPF I've not had a single warning light, it accelerates nicely from 1200rpm, starts first time and the same hill can be taken at 40 in 5th! Fuel consumption is up to just under 30mpg too.

Yes, I've also given the EGR, throttle body and intake manifold a damn good cleaning, sorted the leaky/loose turbo inlet problem, cleaned the MAP sensor and fixed the swirl valves. BUT, all of those (except the turbo inlet) are problems at least in part caused by carp in the system from the combination of DPF and EGR. I haven't even bothered to fully block my EGR yet as when I started to undo everything in preparation it still looked like I'd only just cleaned it.

While I fully appreciate what Old Engineer says above about the pollution side of things, at the same time it's not exactly good for the environment (people included) to run a system which self-cleans (when it can be bothered to work properly) by dumping loads more fuel into the system increasing fuel usage and hydrocarbon emissions. The alternative thrashing, for those of us that do short journeys only, is arguably worse from an ecological point of view and, if like me you don't have a decent stretch of high speed road nearby, comes with a slightly higher accident risk.

I didn't want to risk having a cored DPF and then VOSA changing the rules from a visual test to a functional one, forcing me to replace the DPF completely at a time when people would be looking to buy them quickly before their MOTs with the consequential increase in prices. I picked up a straight pipe from an ebay seller in Italy for £55 including shipping. It has all the mounts in the correct places, plus the boss for the pressure sensor and outlet for temp sensor. It even came with a new set of bolts. If the MOT centre don't know their Alfas then it's possible they may not pick up that there's not a close-coupled DPF hidden by the under-tray as it looks OEM. If they do, then it's a simple 1 hour job to drop the straight pipe and put the DPF back on for the test.
 

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I think you may have a point there mapalfa with regard to close coupled DPF's.

The 2.0 versions have a close coupled DPF but the 1.9 and 2.4 don't.

Unless the tester is well clued up on Alfa's are they really going to know what it should have?

It would be easy to tell the tester that your 2.4 has a close coupled DPF, and unless they have time to either look carefully or look it up then they are unlikely to know.

DPF's only trap around 80% of the soot anyway, and I was surprised by how much crap came out of the back of my G when they tested it for the MOT even though my DPF is fitted and functioning.
 

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I think you may have a point there mapalfa with regard to close coupled DPF's.

The 2.0 versions have a close coupled DPF but the 1.9 and 2.4 don't.

Unless the tester is well clued up on Alfa's are they really going to know what it should have?

It would be easy to tell the tester that your 2.4 has a close coupled DPF, and unless they have time to eaither look carefully or look it up then they are unlikely to know.

DPF's only trap around 80% of the soot anyway, and I was surprised by how much crap came out of the back of my G when they tested it for the MOT even though my DPF is fitted and functioning.
You could, I suppose, go further and weld in a cored close-coupled DPF. That way they'd see something up above the under-tray even if they looked carefully. Who's to say you hadn't "upgraded" they system, after all the regs only say that it must have a DPF if originally fitted with one but, to the best of my knowledge, they don't say it has to be an OEM spec one in the original position.

I don't keep the under-tray on normally, as I'm convinced it's the cause of the notorious sub-frame rot, nor do I keep the top cover on simply because I like to see the engine. But, they're both going back on come MOT time as testers aren't allowed to remove them and anything they should look for that are hidden can't be failed for. A couple of advisories saying that the cover and tray obscure the view is no hassle in comparison to them spotting something they don't like but I'm happy with.
 

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I still have a straight through pipe in my garage if anyone's interested
 
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