Smoke over 4K rpm - Alfa Romeo Forum
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(Post Link) post #1 of 9 Old 01-09-19 Thread Starter
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Smoke over 4K rpm

My Giulietta is remapped and I noticed that with dna on Normal, it is very hard to see any smoke coming out of the exhaust, which is a good thing, but I noticed something on a high rpm.
There’s this road I do every day coming home from work where many times I pull a 4th gear up until the redline and once it gets around 4K rpm, I start to see some smoke coming out.
So I’m thinking that in those rpms, the need for air should be greater and since diesel runs very lean, if the diesel input increases linearly and the air input at some point is not enough, it will result in a richer mixture and consequently start producing smoke.
Could this be the case?
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What colour is the smoke?
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(Post Link) post #3 of 9 Old 02-09-19 Thread Starter
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Quote:
Originally Posted by Roo1valk View Post
What colour is the smoke?
Black, like unburned diesel
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Check for boost leaks and air filter condition initially as black is sign of poor combustion possibly from loss of air.
Also have you plugged MES in to see what injector correction is like and if any fault codes?
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(Post Link) post #5 of 9 Old 09-09-19 Thread Starter
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I haven’t yet connected MES but I believe any boost leaks would be visible on the dyno and the lines on both N and D seem quite smooth (image attached).
Anyway, one thing that I remember is the boost pressure gauge on the Giulietta dropping the second bar shortly after 3.5K rpm when it was stock. After this remap, it started dropping only one bar at 4K rpm. So, could this be related with the smoke at those rpm? Since the boost pressure drops at that point, could this lead to a richer mixture and therefore smoke?
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Last edited by grimreaper166; 09-09-19 at 16:01.
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I was thinking it would smoke more as it could be dumping more fuel in at high revs. The tuner should be able to tell you
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Our Giulietta Diesel smokes at High RPM too, it is standard. Always has done since we bought it...

DPF's only stop around 80% of particulate emmisions from what I have heard so quite a bit of small particulate matter will still get through.
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Our Giulietta Diesel smokes at High RPM too, it is standard. Always has done since we bought it...

DPF's only stop around 80% of particulate emmisions from what I have heard so quite a bit of small particulate matter will still get through.
Have you bought it new or second hand?
I doubt it should smoke at all as I see a lot of these cars with completely clean exhaust..
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Quote:
Originally Posted by tydytek View Post
Have you bought it new or second hand?
I doubt it should smoke at all as I see a lot of these cars with completely clean exhaust..
Bought 4 years ago, at 60,000 miles from a regular used car dealer. One previous owner which was a company.

I have had a look at the DPF and it appears not to have been tampered with. No cuts, welds etc.

The exhaust does get black over time.
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