Abnormal fuel consumption problems

[bigjohn]

On 2/13/2018 at 22:32, juanse_2691 said:

Quick update: I went to change my spark plugs (Putting new NGK BKR6EIX-11 iridium spark plugs) and spark plug from cylinder number 1 was caked in oil. The valve cover is out for a reseal and I'm cleaning the injection nozzles as well. Tomorrow we'll see. 

 

See my earlier post on crankcase breather - this is a common problem on these engines (especially if mileage is low and just driven on short trips) and can cause potential oil burning or plug fouling

 

There is a really bad design fault inside the air filter. The rubber oil breather pipe fixes to the side of the air filter housing which then has an internal pipe within it that seems to get cold and condense oil vapour forming an oil sludge/mayonnaise that blocks the tube especially near the one way valve at the end of it.

 

This pressurises the crankcase and can blow oil past the valve seals - and past gaskets, seals etc..

 

I keep an eye on mine having suffered an oil issue a few years ago solved by cleaning the airfilter pipe out. another thing to keep an eye on is the oil seperator/breather module attached to the back of the engine (the other end of the rubber oil breather pipe) this can block/sludge up as well. A simple test is to remove the oil filler cap and then pull off the oil breather pipe from the air filter and then blow down the rubber pipe - any resistance/gurgling then this needs clearing out as well. Strangely this used to be a previous gen Polo 8v engine issue (circa 1984+) as well

 

 

 

 

 

Edited 16 February, 2018 by bigjohn

[Breezy_Pete]

Checking the breather system is a good idea, but on the BBZ I don't think there's a pipe like you describe. Breather outlet goes to inlet manifold under throttle body.

[bigjohn]

6 minutes ago, Wino said:

Checking the breather system is a good idea, but on the BBZ I don't think there's a pipe like you describe. Breather outlet goes to inlet manifold under throttle body.

 

Fair enough - was worth a thought. Glad they got rid of that carp design.

 

Does this engine have the oil seperator / breather module on the back of the engine?

Edited 16 February, 2018 by bigjohn

[juanse_2691]

Will have a look at the oil pipe inside the air filter housing. So far it seems like some economy has been gained after the spark plug change and injector valves cleaning, the day before yesterday I had a spirited 70-mile drive through A and B-roads , but with a lot of stops, sadly (construction crews and stuff) and averaged 35.7 MPG imperial, which was unheard of  best I could manage before: 26.1 mpg).

 

Also, after two days of city driving (lots of stop and go traffic, plus long waits idling) the average is still a very healthy 8.9 l/100 km (31 mpg imperial). That's with the A/C running most of the time. 

 

Just refueled today, let's see how much this tank lasts.

[Breezy_Pete]

19 hours ago, bigjohn said:

Does this engine have the oil seperator / breather module on the back of the engine?

 

Yes mate, circled in orange here. Corrugated pipe is the outlet up to inlet manifold. Only breather-related pipe going to the airbox is the thin one on the (RHD) passenger side which is a fresh air inlet pipe (with non-return valve at the point it enters the cam cover).

 

[juanse_2691]

About my problem with fuel consumption, turns out it was (it is?) a combination of factors: 
 

-My warm air intake mix flap was stuck in the "hot" position, depriving my engine from oxygen and fresh air. In those conditions, any engine tends to run rich. 
 

-One of the front wheels was slightly stuck (the brake pads were seized) offering way too much rolling resistance. 
 

-The MAP (Manifold Absolute Pressure sensor) and the throttle body were full of soot, decreasing engine response and making it necessary to accelerate more for any load. 

 

-Oil was getting burned because it was leaking from the valve cover.
 

To remedy all that I switched to iridium spark plugs (which offer improved idle stability and quicker response), shut the warm air intake flap in the 'cold' position (I live in a subtropical climate anyway) and cleaned the throttle body and MAP, solved the valve cover problem (resealed it), and serviced the brakes. Now it's usual to see fuel ratings about the 6l/100km figure when traveling with the AC on and at 100/120km/h, which is pretty good in my book. City driving mileage is still pretty bad though, but is all down to how my city has been planned (or the lack of it: bottlenecks everywhere, lots of bumper to bumper traffic, lots of idling). Otherwise it's all pretty reasonable. 
 

Also a contributing factor that I haven't had the opportunity to test, is the quality of fuel. I can only use 91 RON since is the highest quality fuel I can get where I live. I suppose things would be different with the required 98 RON. 
 

Well this has been my experience, hope that it helps anyone in the future. 

I'll leave the thread open just in case. 

Edited 20 November, 2018 by juanse_2691
Added the brake service to the list.

[YS53]

That appears to be about 40mpg - So sounds pretty good Juanse -  especially if you can only get 91 ron fuel !

Edited 20 November, 2018 by YS53

[_YoYi_]

17 hours ago, juanse_2691 said:

-My warm air intake mix flap was stuck in the "hot" position, depriving my engine from oxygen and fresh air. In those conditions, any engine tends to run rich. 

Hi Juanse

 

Can you please provide more details on this? First time I read about warm air intake mix flap

 

Thanks

[juanse_2691]

6 hours ago, _YoYi_ said:

Hi Juanse

 

Can you please provide more details on this? First time I read about warm air intake mix flap

 

Thanks

 

Inside the air intake housing on top of the AUA/AUB/BBY/BBZ et al engines, there's a thermostatically controlled flap which diverts fresh air (ambient air) or warm air (from exhaust manifold) depending on external temperature. The flap is supposed to be open by default, only getting in the 'hot air' position when temperatures below 0°C are reached. Well, in my case, the flap was stuck on the 'hot air' setting, which is a nuissance considering temperatures normally exceed the 30°C mark where I live. 

This excerpt from the SSP35 regarding the the AUA/AUB engines explains it better:

[Breezy_Pete]

It also works the same way in the 1.2/12-valve engines, AZQ and BME codes. Not sure if any others.

The fundamental problem is this design fails in the 'all hot' position rather than the 'all cool', when the thermostat no longer works.

Edited 21 November, 2018 by Wino

[jamos316]

On 08/01/2018 at 18:48, juanse_2691 said:

Hello people,

 

This is my first post here.

 

I own a 2007 Škoda Fabia Elegance, 1.4 16v, it's the BBZ engine (101 bhp). 

 

I have an expensive and annoying problem with it. It's just consuming petrol as if it were dumping it down the drain.

 

This week I topped the tank. Drove it until the reserve light came on. 10.014 gallons. And I only managed to get 140.8 kms (roughly 87.5 miles) out of it. That's about 14 km per gallon (US) or 27 l/100 km. That's absurdly high. 

 

Apart from the high fuel consumption I have no symptoms of an issue. 

 

I suspect a broken coolant temperature sensor is the culprit. Do you guys have some input on what may be wrong with my vehicle? 

 

Thanks in advance. 

 

27l/100km is way too high. Did you manage to sort this?

 

I have a similar problem. I have just bought a new fabia combi and driven it for over a week. I am averaging 9l/100km which I think is too high as it should be getting at least 5.5l/100km.

 

Am thinking that it could sort itself the more I drive it but it is a concern

[juanse_2691]

5 hours ago, jamos316 said:

 

27l/100km is way too high. Did you manage to sort this?

 

I have a similar problem. I have just bought a new fabia combi and driven it for over a week. I am averaging 9l/100km which I think is too high as it should be getting at least 5.5l/100km.

 

Am thinking that it could sort itself the more I drive it but it is a concern

Hello @jamos316, I've managed to solve the problem somehow, by doing routine mainteinance (brakes, oil, filters,) and poking around my air filter housing which had a restricted piping; also updated my spark plugs (installed iridiumIX NGKs). You can find what else I did reading the full post:

 

 

On 19/11/2018 at 21:39, juanse_2691 said:

About my problem with fuel consumption, turns out it was (it is?) a combination of factors: 
 

-My warm air intake mix flap was stuck in the "hot" position, depriving my engine from oxygen and fresh air. In those conditions, any engine tends to run rich. 
 

-One of the front wheels was slightly stuck (the brake pads were seized) offering way too much rolling resistance. 
 

-The MAP (Manifold Absolute Pressure sensor) and the throttle body were full of soot, decreasing engine response and making it necessary to accelerate more for any load. 

 

-Oil was getting burned because it was leaking from the valve cover.
 

To remedy all that I switched to iridium spark plugs (which offer improved idle stability and quicker response), shut the warm air intake flap in the 'cold' position (I live in a subtropical climate anyway) and cleaned the throttle body and MAP, solved the valve cover problem (resealed it), and serviced the brakes. Now it's usual to see fuel ratings about the 6l/100km figure when traveling with the AC on and at 100/120km/h, which is pretty good in my book. City driving mileage is still pretty bad though, but is all down to how my city has been planned (or the lack of it: bottlenecks everywhere, lots of bumper to bumper traffic, lots of idling). Otherwise it's all pretty reasonable. 
 

Also a contributing factor that I haven't had the opportunity to test, is the quality of fuel. I can only use 91 RON since is the highest quality fuel I can get where I live. I suppose things would be different with the required 98 RON. 
 

Well this has been my experience, hope that it helps anyone in the future. 

I'll leave the thread open just in case. 

Go ahead and do some routine mainteinance and use the highest octane fuel you can, and check the results. Also keep your tyres well inflated (pretty much north of 33/35 PSI). Do you use A/C too much? All my figures are with A/C on since I can't stand the heat. I reckon if I didn't use the A/C that much my car would run pretty much out of thin air. 

My driving routine doesn't help at all since I do lots of short trips and I have to keep the car running (for the A/C to work), also traffic lights are a mess where I live which complicates things. I think in a Combi it would be even worse because it's a heavier vehicle. 

 

[juanse_2691]

Will have to check inside the cylinders. Fuel consumption is rising and pinging is abhorrent. Fueling with 95 RON since there's nothing else available. I'll need to check fuel trims and the whole lot, there's no way a full tank lasts less than 250 miles in long trips, unloaded and with conservative driving. 

[ChrisMG]

On 17/02/2018 at 12:51, Wino said:

 

Yes mate, circled in orange here. Corrugated pipe is the outlet up to inlet manifold. Only breather-related pipe going to the airbox is the thin one on the (RHD) passenger side which is a fresh air inlet pipe (with non-return valve at the point it enters the cam cover).

 

Hi Wino, my name is Chris, i see your motor photo I want to consult you, my skoda fabia 1.4 16v bbz, it has been turning off after a 10-15 minutes at idle, previously I had problems with my respirator that you point out in photos and it was changed for a generic VYKA brand, but now it keeps turning off and I hear a sound like  if it were to blow from the small hole in the vent (on one side of the diaphragm) is this normal ??  additionally I only have an error in my lambda probe B1 S1 that I do not think is the cause of my car turning off, the sound of the breather is very loud at times and then it loses power and turns off, I appreciate your help friend.

[TMB]

Why are you ignoring the faulty pre-cat lambda probe? When you get faults showing with the lambda heater, it's usually the probe itself rather than its wiring.

[ChrisMG]

13 hours ago, TMB said:

I will buy a new probe, I have been thinking and analyzing how reliable vagcom is with that information, if my only mistake is Probe bank 1 that must surely be my problem, thank you very much.