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The issue described by the OP sounds like a problem with the in-tank fuel pump (not the high pressure one on the engine). The only way to test it is to tap into the fuel line and attach a gauge.
That’s fine then! However, for the sake of five minute test he can eliminate the NTC sensor.

My Ascaris however, are no longer for sale. At last, my exhaust now sounds really good. Alfa boxes breaking up at high revs but there is nothing - absolutely nothing emanating from the exhaust system before the boxes.

Starting the car this morning and it took a little over a minute for the engine to settle at 750 rpm and with it, noise levels settled out to a slightly louder than quiet tick-over. Perhaps I will get back the sound the Ascaris make above 3000 rpm.(y)(y)(y)(y)(y)(y)
 

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On cold starts those of you that have a 3.2 is there a faint smell of fuel from the exhaust. The kind of smell you get when there is a slightly enriched mixture?

Thanks

Nick
 

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On cold starts those of you that have a 3.2 is there a faint smell of fuel from the exhaust. The kind of smell you get when there is a slightly enriched mixture?

Thanks

Nick
Yes, but I would argue it is normal. The ECU does not inject extra fuel as with a conventional PFI engine or a choke with carburettors, it uses the valve timing to starve the engine of oxygen so the mixture appears rich for the amount of air that has been inhaled.

And the NTC Sensor, in the water jacket, close to number two cylinders exhaust port - as close as they could physically get to the manifold cat, is used to sense when the temperature is up to ”Catalytic Light - Off” temperature.

Until it is, the exhaust camshaft is advanced beyond a “Normal Operating Angle”, opening the the exhaust valve early.

In doing so, it is releasing the cylinder “Charge” early, when the burn is incomplete. The Hot gases heat the man cats and the unburnt HC’s start a chemical reaction within the capillaries, further raising the temperature to “Light-off”.

Inevitably, during his phase there will be some fuel which is unburnt and not converted by chemical action - in other words remains as fuel/petrol, which will find its way out of the tail pipes.

Once temperatures are up, sensed by the NTC, and the exhaust camshafts have retarded to their normal “Working Angles”, combustion is virtually 100% and no petrol fumes make it the tail pipes.
 

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I do not have that smell. There is no smell of unburnt fuel. It smells like from start that the car is running at normal operating temp hence no smell of unburnt fuel. I am now wondering if I underfuelling on cold start despite the cold start fuel pressure being about 55 bar?
 

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I do not have that smell. There is no smell of unburnt fuel. It smells like from start that the car is running at normal operating temp hence no smell of unburnt fuel. I am now wondering if I underfuelling on cold start despite the cold start fuel pressure being about 55 bar?
What ever Nick, I’m just explaining how I believe the system works.

However, it is not uncommon to overthink a problem. Eliminate the issues which are cheapest and easiest to test/replace.

I had not appreciated just how important that NTC sensor is. And it still amazes me that it cost 7 quid. But, before I bought it, it took me five minutes to confirm it was a problem for me/my engine. It may not be the only problem but it certainly was one.

If my NTC had gone short circuit/low impedance, it would indicate to the ECU that the engine is up to temperature and the exhaust camshaft would be retarded. At the same time, to what ever degree, the inlet camshafts would have advanced. Under those conditions, it would be difficult to start the engine and this excludes the effect it has on spark advance.

The 3.2 JTS engine is incredibly easy to start as the Static valve timing creates a very low compressive load - the inlet not opening till 11.5deg. Atdc and the exhaust not closing till 9deg. Atdc.

So if the starter motor is struggling, it could be indicative of valve timing errors. And the NTC Sensor has a direct bearing on that!
 

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Apologies, I did not want to come across as rude, I was simply trying to convey I expected the smell of some unburnt fuel. I replaced the temp sensor, think it was about the same cost as yours. The one I removed was Bosch and replaced it with a cheap one costing about the same as yours. Guess this sensor could be faulty but suspect the problem lies elsewhere and any thoughts or comments are most welcome.

Again thanks

Nick
 

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Apologies, I did not want to come across as rude, I was simply trying to convey I expected the smell of some unburnt fuel. I replaced the temp sensor, think it was about the same cost as yours. The one I removed was Bosch and replaced it with a cheap one costing about the same as yours. Guess this sensor could be faulty but suspect the problem lies elsewhere and any thoughts or comments are most welcome.

Again thanks

Nick
Nothing to apologise for.

It is possible the one you replaced is faulty, but the best way to find out is with a DVM.

You could just try leaving it disconnected. That would pseudo create a “engine temperature low” and it may assume the default cam positions - inlets retarded and exhausts advanced.

There are two possibilities, 1) the engine refuses to start as the ECU has gone into safe mode, or 2) it is incredibly easy to start the motor.

It will do no harm to the engine as the NTC could fail at any time in service so I think the software will protect the engine.
 

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Disconnecting the temp sensor got a host of faults, typical when it panics. VSR, hill hold, ESR all failed. Started the car and smelt fuel from the exhausts as you would expect! Drove it and no hesitation! Will order a new Bosch sensor and see how that goes.

Do you know what make the one you purchased was. The new one I bought the probe was slightly narrower in diameter.

Thanks

Nick
 

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The original sensor in my car was a Bosch 0 280 130 122 however checking some suppliers according to their parts list this is the wrong one?

Thanks

Nick
 

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Disconnecting the temp sensor got a host of faults, typical when it panics. VSR, hill hold, ESR all failed. Started the car and smelt fuel from the exhausts as you would expect! Drove it and no hesitation! Will order a new Bosch sensor and see how that goes.

Do you know what make the one you purchased was. The new one I bought the probe was slightly narrower in diameter.

Thanks

Nick
Well done Nick. The sensor I bought is made by Delphi. I bought a set of coil packs made by them and they have been fine. They were bought recently by Borg-Warner so they are a quality company. But an awful lot cheaper than Bosch.

I can see the argument for buying a Bosch part but the price is a bit silly. And to be fair, the actual device is really quite simple. But clearly given where it is used it needs to be pretty robust. So I think the Bosch will have good cyclic stress characteristics - won’t break down too easily.

Again this confirms the sensor is off the same port as the VSR, Hill Hold, ESR and fuel gauge. I hope the absolute pressure sensor is also from the same port.
 

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I’ll check that out tomorrow.

The Delphi is a TS10253, EAN5012759464779
Not been able to do much today, other than “Flooring”. But I was running on empty and decided to stop and take dip at the local “Watering Hole”.

We sat under the open porch/veranda and had a glass of wine - my wife, and a couple of pints of Abbot - me. Sun and Hail and pelting rain!

Paid and left to drive up the hill - pub under a mile from home. Started the engine - dash clear of all alarms!

Nothing else has been touched for many weeks as I have been monitoring the performance of the Porsche 055 MAF element.

Tests indicated the NTC was faulty; driving tests indicated with new sensor, performance - sound wise - was much less crude and noise levels down sufficiently to deceive one to believe there isn’t too much different from the way it sounds, compared to a standard 159 Q4.

Until I hit the throttle! Just as it should be!

All for a Seven Quid Sensor!

Ascaris to go back on!
 

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“In this system, the ECU receives signals from the camshaft position sensor, crankshaft sensor, oil temperature sensor, mass air flow sensor (MAF), and the engine coolant temperature sensor and uses the information to adjust its output signal to an oil control valve. This valve acts as a hydraulic actuator, rotating a rotor (which is connected to the camshaft) inside a housing, which is connected to the crankshaft via a timing chain. Once the ECU has changed the cam phase angle, the ECU continues to receive inputs from all of the sensors and continually adjusts the oil feed to the rotor. Like electronic throttle control, this is a closed loop system, which means that the difference between the current camshaft phase angle and the optimal camshaft angle is the "error signal" that is sent to the ECU. The computer uses the error signal to adjust its output to the actuator to get the camshaft phase angle where it needs to be.”

Just thought I’d post this little snippet, which addresses the issue of sensors involved in setting valve timing.

Not sure if oil temperature is involved in the Alfa system however.
 

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Thanks for clarifying that point - appreciated (y)
In everything I've read on the ECU it does take oil temperature, and therefore viscosity, into effect when activating the VVT solenoids on a cold start situation. The engine doesn't suffer any ill effects if the oil temp sensor is broken (hence why there is no dedicated oil temp BCM code but there is oil level), and the gauge is only driven by a MCU in the gauge cluster and isn't connected to the CAN in a 'smart' way to affect any operation 🙌
 

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I would be interested too know how it takes oil temperature into account without an oil temperature sensor, other than the one in the sump which as you say is “”Stand - Alone”?

But maybe this is one of the reasons why they are so specific about the oil they recommend, knowing it’s Viscosity/Temperature Characteristic and have programmed values into the ECU, perhaps it correlating with the water temperature sensor??

Fascinating stuff really. And why not, as beyond the embedded default map, the ECU is acting predictively!
 

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I would be interested too know how it takes oil temperature into account without an oil temperature sensor, other than the one in the sump which as you say is “”Stand - Alone”?

But maybe this is one of the reasons why they are so specific about the oil they recommend, knowing it’s Viscosity/Temperature Characteristic and have programmed values into the ECU, perhaps it correlating with the water temperature sensor??

Fascinating stuff really. And why not, as beyond the embedded default map, the ECU is acting predictively!
Neglected to say, thanks for your input George - much appreciate. 👏
 

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Discussion Starter · #60 ·
Fuel pump inspected today. It is in mint condition and therefore not the cause of the issue. No leaks, no cracks. Output is within the expected parameters.
 
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