Technical Fiat Panda 169/2005 High Fuel Consumption on idle/stationary

[Lullaby]

I am not sure of you're problem, the only thing I can tell is my experience that almost was the same.

1. Started to check every hose of the air intake to check for broken or small cuts. Checkt the intake itself for good sealing to avoid dust in the EGR.
2.Took out the EGR to check for grease or dust and clean it.
3. Pulled out the Injectors to give a good clean.
4. Pulled out the spark plugs to see if one was withe or greasy and replaced them all. (white is burnt do to a to hot cilinder, cause can be leaking .... ring ore how you call it)).
5. Checkout the head gasket ( I mean the gasket to the cat.) for leaking (misreading O2 when leaking and gives a smell)
6. Took out the 2 Lambdas (O2) and measured if they where close to .9 and they where way off and carbonated (head up to 600 degrees and when the burner is taken away, they must be dropping in second of .9 to ... )
7. Search every pipe of fuel injection for leakage.

Dit every thing and find out that there was a micro leak at the air intake, 1 spark plug was white, O2 both gone. Replace every thing and the problem was gone, no smell, no excesses fuel consumption. All cost together around 120 pound and knowing that my cat. is safe now. I can't say if you have the same kind of problems, I only can say it helpt my problem of excessive consumption. The only thing left for my is to check (extra) the compression of the cilinders do to the fact that one of my spark plugs was oily.

I hope you can find the problem and wish you the best solution.

 

[marinosg]

ok, thank you (all) very much for valuable comments and suggestions.
I will be away for the next few weeks, so let me further work on the smell problem during those weeks, and also take some new measurements/data

I will get back...

 

[koalar]

1. Started to check every hose of the air intake to check for broken or small cuts. Checkt the intake itself for good sealing to avoid dust in the EGR.
2.Took out the EGR to check for grease or dust and clean it.

Are the 1.1 and 1.2 engine different in the Netherlands not seen one here fitted with a EGR only the 1.3D

Might be a translation thing

 

[Zardo]

The tank gets empty incredibly fast. Previously, I was able to run approx. 400-500km by driving within the city with a full tank. Now I get approx.150-200km with a full tank by driving within the city.

If the spark plugs show a normal greyish colour (not blackish) then such a drastic increase in fuel consumption could be explained by a fuel leak.

Maybe fuel is only leaking when the fuel pump powers the fuel pressure. Is there an abnormal smell?

Other possibilities: contaminated fuel, clogged air filter, clogged exhaust, ignition and/or valve timing off, weak ignition spark, mixture issue, way too much engine oil (overfill), some serious issue with wheel bearings, tire pressure way to low, some permanent braking going on...

Does the car still reach its top speed (no power loss?)

 

[DaveMcT]

I had a Punto Mk2 HGT with a (semi) seized brake getting hot. Fuel consumptions was near normal. When it went fully t*ts up I couldn't drive the car which I guess fixed the fuel consumption.

 

[Zardo]

ah yes, I forgot: check engine compression. Inefficient compression because of engine wear & tear will result in power loss and increase fuel consumption because the efficiency of the engine goes down.

 

[marinosg]

I noticed that gasoline smell seems to be coming from the exhaust (not engine bay).

Overall speaking, an engine running rich can emit fuel smell, especially at idle - and I believe this the case for my panda. Let me try to summarize below some common causes for such issue:

- faulty coolant temperature sensor.
Comment: I replaced this sensor 1,5 years ago so I don't believe this could be the root cause.

- stuck open fuel injector
Comment: I had my injectors checked and cleaned by a proffesional. Unless this guy was a total crook, I believe we can skip this cause as well.

- faulty mass air flow sensor
comment: there is no such sensor available in the panda.

- incorrect ignition timing
comment: my last big/full service in my panda (including replacing timing belt) was 4 years ago. I plan to repeat next summer. In theory, there is always a chance that the belt may have skipped a tooth and timing may not be correct. How can I confirm this? I hear there are some marks... but where can I find them and how can I check?

- dirty air filter
comment: my air filter is not new, but it is not that dirty either. I replaced it 4 years ago as part of that big/full serivce, but keep in mind that I am not using the car a lot during year. On average, I drive approx. 4000-5000km per year. Anyway, I tried to blow some pressurized air through it to clean it, I even tried driving around without it - no change in car behavior.

- faulty oxygen sensor.
comment: this is still bothering me. Even though the graph seems to be normal at 2000RPM, I understand it does not look normal at 800RPM (idle). I will try swapping the two sensors and I will try to replace the pre-cat with another sensor that I have spare (this is a used part / not new, but functional).

- faulty map sensor
comment: I have tried cleaning this with some cleaner spray. Is there some way I can confirm proper operation of the sensor?

- faulty intake air temperature sensor
comment: where is this located in the panda?

- faulty fuel pressure regulator
comment: to my understanding, there is not such thing in panda

- lack of engine compression
comment: this may be challenging to check, I believe this needs to be checked by professional in garage? is there something I can check myself?

- vacuum leak ?

- spark plugs



all above are potential causes keeping in mind that the smell is coming from the exhaust. I am not mentioning anything about fuel leak here, because this would impact also the milage while driving on road trip (outside of city) - but this is not the case for me.


I will share update when I swap the O2 sensors

 

[koalar]

Right smell of petrol from exhaust

Unburnt fuel passing through the cylinders equals higher fuel consumption. It’s more likely to be a misfire than running rich. Especially with the erratic O2 readings

A compression test would eliminate or confirm two different common possibilities

Down on all cylinders would be a timing issue

Down on two adjacent cylinders would be head gasket

A local independent garage will do it for a small charge

When I needed to check mine I bit the bullet and bought a compression tester there are about £10-£15 online about the same as a garage would charge but I have the convenience of owning it for future testing

Very simple and quick to use they come with instructions

 

[koalar]

The fuel pressure regulator is built into the pump. I have never seen one give over pressure. Very unlikely in my opinion

 

[koalar]

Ambient temperature sensor is built into the MAP sensor

The easiest way to test this is with a scan tool

Data log the temperature. Should start at what google says the temperature is in your town and slowly rise as the engine heats up

 

[koalar]

MAP sensor is a little more challenging to test. You can data log the pressure and watch it change as the throttle is opened and closed. Engine off should read close to what google says the pressure is

 

[koalar]

These engines 1.1 and 1.2 don’t often suffer from vacuum leaks

Anything above the throttle body makes no difference what so ever

A small leak below the throttle body is still seen by the MAP sensor and compensated for

The only place that a small leak is a problem is between the inlet manifold and cylinder head

A quick test is a squeeze spay bottle of water or a can of WD40 Start the engine and lightly spray the joins that you suspect. If there is a leak as the water or WD40 is sucked in the engine revs will alter

A leak in the exhaust manifold before the O2 sensor will increase the fuel

Broken exhaust studs and cracked manifold/CAT are fairly common. You can normally hear, see soot and feel any problems.

 

[koalar]

My gut feeling is the O2 sensor is seeing Unburnt fuel due to a low rev misfire

You can normally see this on the fuel trims at idle both the sort and long go plus. As you raise and hold higher revs they go back to normal

As the O2 look normal at higher revs is suspect the O2 are fine.


However I am a believer in doing the simple and free first

Changing the sensors over falls into this category. I did this when diagnosing my own car. If it just eliminates one possibility it’s worth doing. Change is easiest when the engine is hot

 

[timmycm850]

Yeah. Your not going to Get many miles to the gallon if you idle at stand still.

Many handbooks discourage idling to warm up in wintertime.

Tim

 

[DaveMcT]

I had a single cylinder misfire on the motorbike. Fuel consumption more than halved when I replaced the broken coil. A few miles later the other one went down. Apparently, "they all do that Sir". The O2 sensor sees unburnt oxygen so turns up the fuel flow, which soots up the plugs and makes the problem even worse.

 

[koalar]

Here’s my pre and post O2 at idle
Hot engine
Left to settle for a bit

Which didn’t look the same as the original posters in my opinion

 

[koalar]

The post cat o2 stays below .2V