Help again! Polo 6n 1.4 Very high consumption

[VAG Fan]

Sorry, I missed that you had already changed the coolant temp sensor. Not sure about the MAP - somebody else would have to advise. My idea was triggered by what you wrote about summer and winter.

[missioner]

If the fuel pressures are lower than spec, then your main culprit is the fuel pump.

OP you mentioned earlier in the thread that the car has over 300k on the clock, I doubt the pump has ever been replaced.

I have yet to find a car that can tell you it's fuel pump is faulty by diagnostic computer and it's reasonably common type of wear and tear failure.

By contrast fuel injectors are very rare items that get replaced due to being worn out.

[Jasondj]

If the fuel pressures are lower than spec, then your main culprit is the fuel pump.

OP you mentioned earlier in the thread that the car has over 300k on the clock, I doubt the pump has ever been replaced.

I have yet to find a car that can tell you it's fuel pump is faulty by diagnostic computer and it's reasonably common type of wear and tear failure.

By contrast fuel injectors are very rare items that get replaced due to being worn out.

Went trough the records and nothing states that the pump was replaced (intensive records was kept by previous owner(Woolworths))

Ok so car was on the dyno. When i picked up the car the guys who done the testing left but they wrote down the following values, which makes no sense to me.

Startup: 13.8:1
Idle: 16.0:1
Underload: 15.6:1

They wrote down car is running lean.

This means that either my pump is shot/blocked seeing that the pressure is also lower than normal. While im at it, should i replace the fuel pressure regulator?



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[panic-mechanic]

fuel pressure regulators rarely fail. do the pump first. A very lean car will use fuel because you use a lot bigger throttle opening than needed.
Swop the pump and take it from there.

[Mal_Jan]

Hi Jason

I have exactly the same issue as you, don't know about the fuel consumption yet as we bought the car with this issue.

I just posted a topic with my issue and the list of things I've done.

I read you had the car in for testing, the fuel pressure is lowish as was mine. Fitted the new pump and the pressure was correct but never thought of putting in on a dyno to get the air fuel ratio readings. I've changed everything i can think of that's related to fuel and spark.

Looks like we are in the same boat

[VAG Fan]

Startup: 13.8:1
Idle: 16.0:1
Underload: 15.6:1

I am surprised that idle is leaner than load. If the pump is to blame, I would expect the under-delivery of fuel to be worst under load (high flow), not idle. But that's just a comment from the sideline.

[Mal_Jan]

fuel pressure regulators rarely fail. do the pump first. A very lean car will use fuel because you use a lot bigger throttle opening than needed.
Swop the pump and take it from there.

Thanks Panic

New pump is ordered and will be here friday, will fit it the evening and see how things goes.

Thanks a lot

[Mal_Jan]

Hi Jason

I have exactly the same issue as you, don't know about the fuel consumption yet as we bought the car with this issue.

I just posted a topic with my issue and the list of things I've done.

I read you had the car in for testing, the fuel pressure is lowish as was mine. Fitted the new pump and the pressure was correct but never thought of putting in on a dyno to get the air fuel ratio readings. I've changed everything i can think of that's related to fuel and spark.

Looks like we are in the same boat

More Jan

Ek het jou post gaan op soek, lyk my ons is wel in die selfde boot. Ek hoop net nie probleem kom reg met die pomp, so ver wys als na die pomp toe.

Jy het natuurlik baie meer as ek vervang en die probleem is nogsteeds daar. Het jy als op een slag gedoen?

[Mal_Jan]

Startup: 13.8:1
Idle: 16.0:1
Underload: 15.6:1

I am surprised that idle is leaner than load. If the pump is to blame, I would expect the under-delivery of fuel to be worst under load (high flow), not idle. But that's just a comment from the sideline.

That's how i also understand it, did a few reading on the mixtures last night. It should be worse under load and not the other way around. They might have written down it down incorrectly (Idle and load) but so far both test leans towards the pump.

[panic-mechanic]

The demand on th pump is low at idle. But already that is lean and they would normallynidle around 15'S odd.
Under load the fuelling should go to somewhere in the 13's and some mp9 will even do 12's
So comparing that it is much worse how lean it is compared to the at idle reading.

[Jasondj]

Got the pump yesterday evening. A day sooner than i thought.

Well installed the pump, took me about 40min. Longest part was opening the housing the pump was in, those plastics get so brittle.

Well, took the car for a nice 60km drive last night. I noticed a few things. Throttle response a little better, i can feel i give less throttle to drive 120, in fact i just touched the pedal to drive 100km/h. Going up hill where i know the car use to cut out nothing happened and the best part of all, this morning, no difficult cold start. Im so chuffed its sorted.

Thanks Panic and others for the advice.




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[Nazirullah]

Hello again,

So i had this issue a while ago and went away but now its back and even worse

Current fuel consumption driving mainly 80/20 Town/Freeway driving i get 7.1km/l and mainly open road i get around 10.3km/l. I use to get around 9.5km/l and 13km/l.

I have checked the spark plugs and they almost look lean, little on the light brown side. According to a VW technician at Barons that is a sign of a healthy motor (sitting at 309000km) but he also said that type of economy is a little to high for these cars.

I have replaced the following: Coolant Temp sensor, MAP Sensor and took the car in again to a different guy for timing.

What can be the issue? Computer box giving in? I do get a strong smell of fuel on a cold start but after few second it goes away.

With my little knowledge on cars a car that's over fueling will but the spark plug black?

The guy that did the timing said that these cars really don't give out any readings or error codes. He plugged it in to bring up the revs while doing the timing and also scanned for codes and nothing came up.

Any help or advice will be appreciated

[Nazirullah]

So i had this issue a while ago and went away but now its back and even worse

Current fuel consumption driving mainly 80/20 Town/Freeway driving i get 14.1km/l and mainly open road i get around 14.3km/l. I use to get around 14.5km/l and

I have checked the spark plugs and they almost look lean, little on the light brown side. According to a VW technician at Barons that is a sign of a healthy motor (sitting at 209000km) but he also said that type of economy is a little to high for these cars.

I have replaced the following: Coolant Temp sensor, MAP Sensor and took the car in again to a different guy for timing.

What can be the issue? Computer box giving in? I do get a strong smell of fuel on a cold start but after few second it goes away.

With my little knowledge on cars a car that's over fueling will but the spark plug black?

The guy that did the timing said that these cars really don't give out any readings or error codes. He plugged it in to bring up the revs while doing the timing and also scanned for codes and nothing came up.

[Nazirullah]

Help me

[Nazirullah]

Re: Help again! Polo 9n 1.4 Very high consumption
Post Thu Mar 06, 2025 4:46 am

So i had this issue a while ago and went away but now its back and even worse

Current fuel consumption driving mainly 80/20 Town/Freeway driving i get 14.1km/l and mainly open road i get around 14.3km/l. I use to get around 14.5km/l and

I have checked the spark plugs and they almost look lean, little on the light brown side. According to a VW technician at Barons that is a sign of a healthy motor (sitting at 209000km) but he also said that type of economy is a little to high for these cars.

I have replaced the following: Coolant Temp sensor, MAP Sensor and took the car in again to a different guy for timing.

What can be the issue? Computer box giving in? I do get a strong smell of fuel on a cold start but after few second it goes away.

With my little knowledge on cars a car that's over fueling will but the spark plug black?

The guy that did the timing said that these cars really don't give out any readings or error codes. He plugged it in to bring up the revs while doing the timing and also scanned for codes and nothing came up.

[Jetta2]

14.5km/l = 6.89l/100km
14.3km/l = 6.99l/100km
14.1km/l = 7.09l/100km.

That is as near as dammit as no difference, really. Weather, traffic conditions, different acceleration and braking etc all make a difference to fuel consumption.

[Nazirullah]

My car consumes fourteen liters in any mode. Can you help me

[n.gov3]

My car consumes fourteen liters in any mode. Can you help me

You are reading the fuel consumption incorrectly.
Units measured are km per litre however seem to be reading it as litres per km.

As Jetta 2 mentioned, consumption you are getting is not really bad and variances could just be down to driving style or driving conditions

[Nazirullah]

VW polo 9n 1.4 ver high consumption 14L/100km

I have checked the spark plugs and they almost look lean, little on the light brown side. According to a VW technician at Barons that is a sign of a healthy motor (sitting at 203000km) but he also said that type of economy is a little to high for these cars.

I have replaced the following: Coolant Temp sensor, MAP Sensor and took the car in again to a different guy for timing.

What can be the issue? Computer box giving in? I do get a strong smell of fuel on a cold start but after few second it goes away.

With my little knowledge on cars a car that's over fueling will but the spark plug black?

The guy that did the timing said that these cars really don't give out any readings or error codes. He plugged it in to bring up the revs while doing the timing and also scanned for codes and nothing came up.

[Nazirullah]

Current fuel consumption driving 14L/100km

I have checked the spark plugs and they almost look lean, little on the light brown side. According to a VW technician at Barons that is a sign of a healthy motor (sitting at 203000km) but he also said that type of economy is a little to high for these cars.

I have replaced the following: Coolant Temp sensor, MAP Sensor and took the car in again to a different guy for timing.

What can be the issue? Computer box giving in? I do get a strong smell of fuel on a cold start but after few second it goes away.

With my little knowledge on cars a car that's over fueling will but the spark plug black?

The guy that did the timing said that these cars really don't give out any readings or error codes. He plugged it in to bring up the revs while doing the timing and also scanned for codes and nothing came up.

[Ashveer03]

You are mixing up a polo 9n and 6n 1.4. Two totally different cars with totally different ecus. Please start Ur own thread.

If U have a polo 9n 1.4 with the BLM engine code, what timing is he adjusting by increasing the idle? The ignition timing is ECU controlled.

And if it is a 9n 1.4 BLM, the ECU has adequate info to diagnose an issue. Firstly verify if the car has the correct 3bar fuel filter. Secondly test the oxygen sensor.

[MR.C]

I had a hole in my outlet manifold. Idling was rough, consumption was high.

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