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Technical 500 Diesel - variable exhaust noise

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Technical 500 Diesel - variable exhaust noise

baxwalker

baxwalker

500 - It wrecks your hair
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I'm sure I'm not imagining this.

When on long runs and driving at an indicated 80mph sometimes I get get an obtrusive throaty exhaust 'roar' from the front end. Not ever so loud but still slightly annoying and it will continue for many miles.


When I call into the services for a break and then re-start, I get back up to the same speed again the engine sounds much 'cleaner' and the 'roar' has abated somewhat. (no fuel added btw)


Some trips it does it and other trips it doesn't.


Anyone know what's going on? :confused:

ps. my average consumption is 59mpg on mixed driving.
 
Last edited:
Hi

Thanks for the replies. I am aware of the DPF re-gen but should it do this for a couple of hundred miles or more on a long run and only stop when the engine is shut down and re-started?

I would have thought it was only necessary in short bursts and then stop automatically once the cycle has done it's job.
 
I'm still confused over this regeneration system, I fully understand the principles and realise that under less than ideal conditions, when the exhaust gas temperature doesn't get hot enough to burn off the accumulated soot in the filter then extra fuel is injected and burnt to achieve this end.

Fine so far.

What I don't understand is why, under ideal conditions, ie. driving at a steady 70-80MPH for a sustained period does the ECU need to also run the regeneration programme?

I have had the increased idle speed and upon checking the instant MPG (as suggested by Venters) it reads about 13MPG but should there also be any indication/warning light to show this is taking place?

Also, according to the handbook a warning light comes on when the filter is blocked and it is recommended that you carry on driving until it goes off. Has anybody had this yet?

Have either of you had the software upgrade to update the DPF parameters to see if this makes any difference?

If any tech is able to give a blow by blow account of how the system is programmed to operate my finger is poised above the thanks button in anticipation.
 
Last edited:
grimwau said:
I'm still confused over this regeneration system, I fully understand the principles and realise that under less than ideal conditions, when the exhaust gas temperature doesn't get hot enough to burn off the accumulated soot in the filter then extra fuel is injected and burnt to achieve this end.

Fine so far.

What I don't understand is why, under ideal conditions, ie. driving at a steady 70-80MPH for a sustained period does the ECU need to also run the regeneration programme?

I dont think that there is ever conditions where no "soot" is being collected. My guess is that constant driving at these speed is probably the ideal time to trigger a recycle.

I have had the increased idle speed and upon checking the instant MPG (as suggested by Venters) is reads about 13MPG but should there also be any indication/warning light to show this is taking place?

There isnt any noticable light etc to warn you this is happening. Hence why people are commenting on it. I have noticed my car make a strange engine noise and was also alarmed untill i guessed it was a recycle taking place. Fiat should have flashed the DPF light when in cycle mode to let us know.

Also, according to the handbook a warning light comes on when the filter is blocked and it is recommended that you carry on driving until it goes off. Has anybody had this yet?

Nope never

Have either of you had the software upgrade to update the DPF parameters to see if this makes any difference?

If any tech is able to give a blow by blow account of how the system is programmed to operate my finger is poised above the thanks button in anticipation.
Click to expand...

I would like that too (y)
 
Venters said:
I notice you average MPG is staying the same but does the instant MPG readout fall when it's making the noise?
I'd assume since it's pumping more fuel through the system when regenerating it should fall when it happens?
Click to expand...


Haven't checked that I must admit - usually only have the average consumption on. Will give it a try next time. Thanks
 
grimwau said:
I'm still confused over this regeneration system, I fully understand the principles and realise that under less than ideal conditions, when the exhaust gas temperature doesn't get hot enough to burn off the accumulated soot in the filter then extra fuel is injected and burnt to achieve this end.

Fine so far.

What I don't understand is why, under ideal conditions, ie. driving at a steady 70-80MPH for a sustained period does the ECU need to also run the regeneration programme?

I have had the increased idle speed and upon checking the instant MPG (as suggested by Venters) it reads about 13MPG but should there also be any indication/warning light to show this is taking place?

Also, according to the handbook a warning light comes on when the filter is blocked and it is recommended that you carry on driving until it goes off. Has anybody had this yet?

Have either of you had the software upgrade to update the DPF parameters to see if this makes any difference?

If any tech is able to give a blow by blow account of how the system is programmed to operate my finger is poised above the thanks button in anticipation.
Click to expand...

Ditto - me too - I hate stuff going on without me being aware of what is actually happening. Cheers
 
grimwau said:
Have either of you had the software upgrade to update the DPF parameters to see if this makes any difference?

quote]

Hi Grim

No I haven't had this done yet - not sure what version of software i'm at so it might have been supplied already updated. Bought the car last August and apart from the clutch saga, nothing else has been done to it.

Might book it in soon to be on the safe side.
Click to expand...
 
baxwalker said:
Hi Grim

No I haven't had this done yet - not sure what version of software i'm at so it might have been supplied already updated. Bought the car last August and apart from the clutch saga, nothing else has been done to it.

Might book it in soon to be on the safe side.
Click to expand...

I ordered mine in Feb 2008 and picked it up on May 31st. When did you order yours and do I recall yours was held up at Portbury for a few days for something to be done?
 
grimwau said:
I ordered mine in Feb 2008 and picked it up on May 31st. When did you order yours and do I recall yours was held up at Portbury for a few days for something to be done?
Click to expand...

Hi Grim

No, mine didn't get involved in the Portbury hold up as I already had mine then. Perhaps mine has missed the update.

will keep you posted.

Cheers
 
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