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SAAB 9-3 - Not any old white smoke problem! but a problem! - boney695

Hi

I would be extremely grateful for any input as i have a puzzling situation with my car.

I have a saab 9-3 1.9 tid 2005 and 105,000 miles

I purchased the car and discovered during its first MOT that the dpf innards had been probably removed (weld marks on dpf).

Problem which has been going on for a few months now:

loads of white smoke and what sounds like something blowing. the MPG on the computer sarts to rapidly fall too.

no loss of oil or coolant.

here is the puzzling bit - it only does it randomly. If I turn the ignition off then on, it will stop the smoke / blowing - mpg returns to normal.

it can restart smoking within two minutes or stop completely until the next occurance - i can travel miles without it happening.

It does seem to be getting worse / more frequent.

Please offer any comment as i am clueless and when I took it to a garage and explained, they didnt know either.

Many many thanks

Edited by boney695 on 02/03/2015 at 18:59

SAAB 9-3 - Not any old white smoke problem! but a problem! - dadbif
Possibly the DOF has been removed, but the ECU not re mapped, the car is then trying to do a regen and injecting fuel into the exhaust causing the problem you are experiencing.
SAAB 9-3 - Not any old white smoke problem! but a problem! - boney695

many thanks for your response. I though that could be a possibility but i though for the regen process to kick in then you had to be at constant high revs i.e on a motorway? The problem kicks in at any revs / speed.

thanks

SAAB 9-3 - Not any old white smoke problem! but a problem! - craig-pd130

It varies from manufacturer to manufacturer but most DPF implementations trigger a regeneration, involving extra fuel being post-injected, based on two conditions:

1) when the DPF pressure sensors detect that flow across the DPF has reduced because of soot build-up, and

2) based on a fixed mileage interval, as a failsafe. The interval varies but is usually somewhere between 300 - 600 miles.

The regeneration will stop when you switch off.

SAAB 9-3 - Not any old white smoke problem! but a problem! - boney695

hey thanks for that. Instead of getting rid of the car, do you think paying for a remap with the dpf regen element removed or do you suggest other fixes? thanks.

SAAB 9-3 - Not any old white smoke problem! but a problem! - Quicksilver

Look on Youtube.

People there have put in variable resistors in place of the sensors to make the ECU always think the DPF is free.

I would check out this mod.

No DPF might be an MOT fail in the near future so watch out.

Q.

 

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