DPF Regeneration, EGR, Injectors and Limp Mode! - Alfa Romeo Forum
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(Post Link) post #1 of 4 Old 08-11-15 Thread Starter
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DPF Regeneration, EGR, Injectors and Limp Mode!

I hate newer cars, emission control and the bluddy hippies that brought them shortsightedly into this world!

I have a 2007 159 2.4 JTD , which refuses to stay out of limp mode for barely a minute or two, and will not idle smoothly at all.

I have done a DPF regeneration 3 times, and it recognises that the dpf is clear according to Multiecuscan, yet repeatedly shows P1206 error code, DPF requires replacing or regenerating, within a minute or two of clearing it.

The poor idle is probably down to injectors being misaligned, but is this a default compensation performed deliberately by the ecu?

If i graph the injector corrections on multi-ecu-scan (MES), 1 and 5 wonder hugely to top and bottom of the scale whilst the remaining 3 are similar across the centre of the range. If i pick up the revs, they come back towards the middle until around 2k and above they sit stable almost together for the remainder of the rev range.

Suspecting EGR aswell, this has been pulled off stripped and cleaned, the plunger is free. It already had a partial blank gasket installed, but it was still very very clogged, and according to MES egr is off, and doesn't seem to come on with revs or blips etc, so does that mean it has been deactivated in the software?

MES shows the egr valve is constantly 4% open?

Any idea's on what next?
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File Type: jpg 159 2.4 ds07 hnf injector graph.jpg (91.0 KB, 15 views)

Last edited by shellybean; 08-11-15 at 13:39.
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did you check the working of the dpf pressure sensor?

4% open means closed, think of it as a circuitry check.

Some faults will result in the EGR to stay closed, you can't really know if the egr is disabled unless everything is working ok.

check the current draw or the resistance of the glow plugs, they're important to get smooth running after starting.

there are ways to clean a blocked dpf should that be the case. alcohol based screenwash down the exhaust (lots of it) works, but also dismantling and pressure washing if you're uncomfortable with alitreof flammable product in the exhaust.

Injector calibration doesn't point to poor injectors, it points to poor power production from that cilinder. that can be because of the injector, or because of poor compression or glow plugs not working as they should. Poor compression can be valves, rings, swirl valves etc...

Last edited by Cuore_Sportivo_155; 08-11-15 at 17:28.
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(Post Link) post #3 of 4 Old 08-11-15 Thread Starter
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Hmmm, Interesting?

i assume the pressure sensor is fed pre and post dpf is it, and the sensor looks for significant inbalance to calculate an assumed blockage of some size?

what tolerance is acceptable or normal?, and is that testable within the MES parameters?

Glow plugs?

i hadn't thought they'd have any bearing on the idle once the car is up and running? but if it makes any difference the car idles better when cold and gets worse the more it warms to normal operating temperature.

If the egr was in a mess, i can safely assume the swirls and manifold are too, so maybe a more i depth strip and clean is required.

bloomin cars!
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I'll rephrase that a little!

Having researched the dpf pressure sensor to be a single feed line, i'll assume it merely takes a back pressure reading from the dpf cannister itself yes?

That being the case, what pressures should MES parameters read at, idle and staged upwards?

thanks in advance
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dpf , egr , injectors , limp , mode , regeneration

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