Diesel emissions test fail - quick fix required? - Alfa Romeo Forum
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(Post Link) post #1 of 10 Old 04-07-16 Thread Starter
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Diesel emissions test fail - quick fix required?

fail!

Average of about 2.3 when I needed to meet the newer 1.5 limit by 8 registration days

I made sure to give it a good Italian tune-up before the test, and literally drove it straight into the test bay, so I know it was fully warm and as clean as I could get it. I have used redex additive in the past, but not recently, so I've dumped some of that in the tank. I thought about shoving some through over the weekend, but was worried that I might loosen up some crap that would then cause an issue today.

The air filter was changed a few hundred miles ago, so I know that's OK. I've also run some foam cleaner (I can't remember the make) through the inlet manifold a while ago and that stopped a smoke on initial start issue.

I've read online that removing the air filter for the test can make quite a difference. Is this true as I'd have thought the MAF would just trigger a different mix? Or is that the point?

Any other suggestions?
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Are you 100% sure you don't have a slight air leak? Look on top of your inlet manifold for any black oily residue, this usually means you are getting a bit of a boost leak past the swirl flap bushes, this effectively richens the mixture.

Is your DPF fitted & working?
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(Post Link) post #3 of 10 Old 04-07-16 Thread Starter
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Quote:
Originally Posted by Pud237 View Post
Are you 100% sure you don't have a slight air leak? Look on top of your inlet manifold for any black oily residue, this usually means you are getting a bit of a boost leak past the swirl flap bushes, this effectively richens the mixture.
I'll check for that, cheers.

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Is your DPF fitted & working?
I was under the impression that the DPF filters out particles that aren't tested for?
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Smoke is soot, DPF should normally catch it.. Mostly the 159s I see failing MOT emissions tests are the ones with DPFs replaced with a straight pipe or gutted internally.
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Smoke is soot, DPF should normally catch it.. Mostly the 159s I see failing MOT emissions tests are the ones with DPFs replaced with a straight pipe or gutted internally.
I'll attack it with the pressure washer.

I then may/may not have to refit it
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Shove a load of Redex in, but still shouldn't make that much smoke
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find a local supplier of Biodiesel (there are an increasing number around, you might have to google it or ask around)

stick a 50% mix in (50% bio, 50% supermarket (Morrisons))

I used to run 100% Bio in my last 1.9JTDm with no issues and no emissions (every MOT I had came up with 0% when tested)

Axe.
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(Post Link) post #8 of 10 Old 05-07-16 Thread Starter
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I can't find anywhere within a sensible distance that sells biodiesel. Bugger!
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(Post Link) post #9 of 10 Old 07-07-16 Thread Starter
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0.27

It's amazing what difference a loose pipe on the engine side of the MAF can make
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(Post Link) post #10 of 10 Old 12-07-16 Thread Starter
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Pipe back on, lean fuel mix gone and all back to normal.
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