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Discussion Starter #1
Having following codes appear (reading on multiecuscan) although no light on dash appeared. This is the third time I'm reseting these.
GTA has CF2 manifolds with equal lenght pipes, standard cats/silenced center and SS backbox. Rear lambda connectors have been swaped due to equal lenght pipes crossing over.

Maf has been changed recently with original part. I didn't have errors before cf2.

Any ideas?

READING ERROR CODES:

1: P1172 - Mixture correction (multiplicative)

ERROR DETAILS:
Engine temperature: 78,0 °C
Engine speed: 2680 rpm
Engine load: 49,50 %
Air temperature: 9,0 °C
Throttle position: 24,31 deg.
Battery voltage: 14,243 V

The ECU has run out of range in adapting the mixture in reference to the O2 Sensor signal (multiplicative adaptation) and/or in reference to the engine running conditions (additive adaptation).
Possible causes:
- Engine Temperature sensor/circuit defective, but the signal still in realistic range.
- Fuel Pressure incorrect
- Fuel Injector(s) leaking
- Fuel Injectors clogged
- Incomplete combustion (ignition or compression problem, excess O2 in the exhaust)
- Vacuum leak (lean mixture)
- Oxygen Sensor defective or contaminated with silica (Voltage change extremely slow)
- Exhaust system leak upstream of the O2 Sensor (stray air brings extra O2 making the mixture to appear lean)
- Fuel Evaporation Control system defective
- vehicle driven out of fuel (tank empty)

The reason for this fault is that ECU has received very high signal from the sensor. The fault is present now. Take appropriate action to fix this sensor fault. Dashboard warning light was activated for this fault.

2: P1175 - Mixture 2 strength *(multiplicative)

ERROR DETAILS:
Engine temperature: 78,0 °C
Engine speed: 2680 rpm
Engine load: 49,50 %
Air temperature: 9,0 °C
Throttle position: 24,31 deg.
Battery voltage: 14,243 V

No help available The reason for this fault is that ECU has received very high signal from the sensor. The fault is present now. Take appropriate action to fix this sensor fault. Dashboard warning light was activated for this fault.

3: P1177 - Mixture Correction (multiplicative) 1

ERROR DETAILS:
Engine temperature: 82,5 °C
Engine speed: 2320 rpm
Engine load: 26,25 %
Air temperature: 21,8 °C
Throttle position: 11,76 deg.
Battery voltage: 14,171 V

The ECU has run out of range in adapting the mixture in reference to the O2 Sensor signal (multiplicative adaptation) and/or in reference to the engine running conditions (additive adaptation).
Possible causes:
- Engine Temperature sensor/circuit defective, but the signal still in realistic range.
- Fuel Pressure incorrect
- Fuel Injector(s) leaking
- Fuel Injectors clogged
- Incomplete combustion (ignition or compression problem, excess O2 in the exhaust)
- Vacuum leak (lean mixture)
- Oxygen Sensor defective or contaminated with silica (Voltage change extremely slow)
- Exhaust system leak upstream of the O2 Sensor (stray air brings extra O2 making the mixture to appear lean)
- Fuel Evaporation Control system defective
- vehicle driven out of fuel (tank empty)

The reason for this fault is that ECU has received very high signal from the sensor. The fault is not detected now, but it is stored in memory. Clear fault codes, and observe for future appearance of the same fault. Dashboard warning light was activated for this fault.

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What vehicle did you source the manifolds from? GTV? 156?
 

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Discussion Starter #5
Have you checked the air intake trunking for splits/cracks?
Checked after reset. Since I have Autolusso silicone bend, no splits are possible and all clamps are tight.
Are these errors indicating lean running that can't be compensated?

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156 manifolds

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Where have you mounted your primary lambda sensors? The 156 V6 CF2 only has one lambda sensor, which is in the downpipes. Have you drilled into the manifolds and welded lambda bosses for them to screw into? This is quite difficult to do correctly, its important that the lambda sensor is at the correct angle with regards to the air flow otherwise it doesn't read correctly.
 

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Discussion Starter #7
Where have you mounted your primary lambda sensors? The 156 V6 CF2 only has one lambda sensor, which is in the downpipes. Have you drilled into the manifolds and welded lambda bosses for them to screw into? This is quite difficult to do correctly, its important that the lambda sensor is at the correct angle with regards to the air flow otherwise it doesn't read correctly.
Rear manifold had lambda boss factory welded as on GTV manifolds. Although I thought these came from GTV, seller was assuring me they are from 156. Both front lambda sensors are installed, front is on downpipe and rear on manifold.

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Rear manifold had lambda boss factory welded as on GTV manifolds. Although I thought these came from GTV, seller was assuring me they are from 156. Both front lambda sensors are installed, front is on downpipe and rear on manifold.

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Possibly from an auto model if the rear manifold had a factory welded lambda boss. I'm pretty sure the auto version CF2s had two lambda sensors instead of one. Its welding in the back bank lambda boss that is tricky, because you are installing it on a bend.
 

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Discussion Starter #10
They do this some time when fitting the CF2 manifolds, this function can be switch off in the engines ECU so the won't see it as a fault, to get this done you would have to send us your ECU

This is based on everything else being correct

Ned
What is exactly that ECU sees as a fault?

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Discussion Starter #12




Only one error when checked today. Also checked fuel trims (photo above)

As I see it ADD (short term) reading negative indicate rich running and MUL (long term) indicate lean condition...

Any ideas?

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Discussion Starter #13
They can be over sensitive without the cats being there

Ned
Don't see the reason as primary lambdas are instaled upstream of pre-cats so readings should really be the same in both situations?

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Discussion Starter #14 (Edited)
Since GTA is used only for weekend cruises I didn't get a chance to deal with this, did a reset a few times but it keeps reminding me.

Anyone with same situation using CF2/decat manifolds?

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Discussion Starter #15
To keep you updated...i have cleaned the TB (pretty sure it did't help with my problem) and fitted back my old MAF...covered arround 300km since and no errors on MES.
Story behind the MAF it that it was first replaced as a precaution and Vauxhall part with same model sensor element/insert was used. Reading somewhere how MAF's are calibrated with housing (alhough can't understand how is it possible and always thought when using same element/insert model makes no difference) made me thinking that I shoud give it a try with old MAF.
Alhough driving with old maf feels a bit sluggis in midrange (3000-4500) i'll leave it to see if it keeps error free and figure out what to do next depending on the result.

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Hi Niko,

I have an 147 GTA with CF2 manifold (156 2.5V6) + Front pipes EL + central cat OEM + Centre pipe with silencer and Twin Pipe Back box SCORPION

I have almost the same fault codes that you !!



The failure happened in slow motion 300 km after installing CF2 exhaust manifolds ...

* at first I started by changing the two lambda sensors ==> no differences ...

* secondly, I looked under the car and took a photo of the probe holder



After discussions with other owners of 147 GTA, they told me that their lambda probe holder was smaller in size.

Like This:




For you, this could be the problem?

thanks in advance
 

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Hi Niko,

I have an 147 GTA with CF2 manifold (156 2.5V6) + Front pipes EL + central cat OEM + Centre pipe with silencer and Twin Pipe Back box SCORPION

I have almost the same fault codes that you !!



The failure happened in slow motion 300 km after installing CF2 exhaust manifolds ...

* at first I started by changing the two lambda sensors ==> no differences ...

* secondly, I looked under the car and took a photo of the probe holder



After discussions with other owners of 147 GTA, they told me that their lambda probe holder was smaller in size.

Like This:




For you, this could be the problem?

thanks in advance
Neither of those lambda boss positions are quite correct - it should look like this (3.0 GTV CF2 manifold). The lambda sensor needs proper penetration into the collector so it can read the exhaust gas correctly as it alters almost every second. Also, you shouldn't have a lambda sensor pointing at all upwards, as condensation will collect inside the exhaust and run down into the sensor.

Cheers

Dan
 

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@Redblood06: Get a different (shorter and perpendicular) lambda boss (on ebay) and reweld everything? Worth a try.

@Pud237: One quick question if you encountered something like this before - after CF2 conversion on 3.2, or maybe after alternator swap for new, at the MOT they could not properly measure rpm and lambda voltage. Rpm reading was jumping from 600 to 1300 perhaps, every second there was 100-200 jump (maybe more). Also lamda voltage was high-ish at the idle and a bit too high over 2200 rpm. Emission on the other side passed with ease. I have a new center cat (OEM for 2.5/3.0 CF2 engine) also, as well as both primary lambdas and MAF. At the official Alfa dealer they had the exactly same problem with measurments.
The year before with CF3 setup everything was ok.
 
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