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

[marinosg]

I have a problem, which although it is not the same, may be related.
The CO2 reading on my Panda (1.2 2005) was always high, with apparent over fueling.
After passing through several workshops, I ended up discovering that the problem was the solenoid valve of the canister system, which was always open.
It is easy to check. You just have to release the ventilation tube from the tank and check that there is absorption.
Here is the valve:

so, I need to:
1) remove/disconnect the blue pipe from the valve (just pull it off?)
2) then start the engine
3) and I should feel some suction at the end of the valve (using my hand/finder).

If I do feel some suction, this means that the valve is stuck open? or what?

 

[marinosg]

I take it the bottom half of the screen is the post catalytic O2 sensor

Doesn’t look right to me. Should be over half way most of the time from memory.

yes, the bottom half is the second O2 sensor (post catalytic).
the engine was cold when I took those snapshots, I should also try when the engine is fully warmed-up to compare...

will do and get back

 

[koalar]

yes, the bottom half is the second O2 sensor (post catalytic).
the engine was cold when I took those snapshots, I should also try when the engine is fully warmed-up to compare...

will do and get back

Sorry I should have said

I am only interested when everything is hot


Until then everything will be all over the place

 

[marinosg]

some update (maybe a new symptom ?)

based on post from Txuchin for solenoid (purge) valve of the canister system, I tried to disconnect the cable and drive around the block just to see what happens. Well, nothing happened (same readings) so I got back home and then re-plugged in the cable.
Then, I turned the key to start the engine, and I got low RPM idle for couple seconds - same behavior as in below video (time stamp 1:47)


this was the first time I experienced this - can we consider this as a symptom of a potentially bad purge valve? or is this related to disconnecting the cable for a while?

 

[marinosg]

Sorry I should have said

I am only interested when everything is hot


Until then everything will be all over the place

I got some new snapshots - having warm engine.
hope this readable

 

[koalar]

Should idle at 750RPM after the first minute or so and not fluctuate

If you disconnect and reconnect things while testing. It is normal for the revs to drop or rise for a second or so until the ECU corrects itself

 

[koalar]

Thanks for the New screenshots

Post catalytic O2 sensor look widely out to me. Whether that’s just an error of the software I can’t say yet


I am correct that the real range on a full tank has been greatly reduced and we are not just talking about the computer display and you have had this car for some time

 

[marinosg]

Thanks for the New screenshots

Post catalytic O2 sensor look widely out to me. Whether that’s just an error of the software I can’t say yet


I am correct that the real range on a full tank has been greatly reduced and we are not just talking about the computer display and you have had this car for some time

yes, correct (for both, real range on a full tank and had this car for some time)

regarding catalytic O2:
- I have a spare (but this is used, not new) O2 sensor, I could connect this one and get some new snapshots...
- or I could try swapping the two sensors to each other (they are exactly the same sensors)...
what would you suggest?

 

[koalar]

yes, correct (for both, real range on a full tank and had this car for some time)

regarding catalytic O2:
- I have a spare (but this is used, not new) O2 sensor, I could connect this one and get some new snapshots...
- or I could try swapping the two sensors to each other (they are exactly the same sensors)...
what would you suggest?

Probably not the cause

Probably showing a low rev misfire

You mentioned a smell of petrol earlier

Any other symptoms. Loss of performance or engine bogs down during acceleration

 

[marinosg]

smell of petrol is occasionally, not consistent.

other symptoms...
I am not really sure... maybe some power loss when on 5th gear but honestly I am not really sure.
What I mean is, that sometimes when I am on the highway on 5th gear, and the road goes somewhat uphill, I sometimes need to switch to 4th gear to maintain a speed of 100km/hour. But I am not really sure if this should be called as a symptom or as normal behavior. It is a small car after all, and honestly I do not remember how this was behaving 2-3 years back as a comparison.
On lower gears the car accelerates fine.

other than that, I cannot think of anything...

 

[marinosg]

I would like to remove that purge valve and try cleaning it, I think it's worth a try.
but how do I take that thing out?

 

[koalar]

I would like to remove that purge valve and try cleaning it, I think it's worth a try.
but how do I take that thing out?

Pull out the metal retaining clip and pull it out of the inlet manifold it’s as simple as that


Although I wouldn’t bother

Just pull the pipe of the end and look at the post o2 sensor reading should be around.6V steady

A small leak on these cars does not effect the running as the total amount of air is still seen by the MAP sensor.

Post a picture of your spark plugs let’s see how each cylinder is burning

 

[DaveMcT]

How about removing the purge valve to see if the problem gets better or worse. Would that give useful information?

 

[09 johno]

Reading through all this, my thoughts are is there actually a problem? fueling use sensors are notoriously inaccurate, at idle or with clutch in fueling is increased to maintain idle, in gear coasting down hill fueling is mostly shut off allowing the cars motion to keep the engine running, has the Op done an overall fuel usage calculation manually ie full tank to full tank, expect less fuel usage on a long run and more in town, changing gear on a hill is normal if the hill is steep, its only a small engine after all..........

 

[koalar]

Reading through all this, my thoughts are is there actually a problem?

Post cat O2 is widely wrong.

Full tank milage a lot less

 

[portland_bill]

Had to do a 12 mile journey today, with no time pressures, so reset my display to km, and to show the instantaneous fuel consumption. Of course, recording them as I drove was not possible, but had to stop at some long-delay traffic signals and wrote stuff down. Here's what I think I remembered.

First, some detail.
2006 Panda 1.2 60hp 137326km
Outside temp 17°C Climate control set to 17.5°C Aircon running
Thermostat seems a little lazy, as it took longer than usual to get to normal temp, on a warm day. (Looks like time to replace the stat.)
From cold start, first few metres showed 25l/100km, reducing quickly to around 15-17l/100km for the first few hundred metres.
Moving at 20km/hr 12-15l/100km, engine still warming up.
Once up to temp:
Off accelerator, back to 25l/100km, which appears to be the maximum it will read.
Slow-moving traffic, 20km/hr 7-8l/100km, 30km/hr 6l/100km
Slightly faster traffic, 70km/hr 4-5l/100km
Average over journey, 5.3l/100km

The average once returned to my normal mpg figure is what I've been experiencing over the last 12 years, so whilst some figures may look thirsty, they seem to be OK, and therefore normal.

I've no idea whether I can record these using MultiECUscan, and create a report or graph, but I may have a look at that at the weekend.

Meanwhile, my advice would be to work on the average only, not instant figures. The instant readout, on any car, is distracting, and potentially dangerous, as it demands attention, when we should all be looking out the windows instead.

 

[koalar]

- This high value of fuel consumption is also reflected in my actual fuel. 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.

I’m working on this
And the fact the O2 reading look wildly out

I really don’t care too much about the computer read out at the moment

 

[marinosg]

some updates:

I unplugged the blue pipe from purge valve and put some tape on the valve to stop air from getting in the valve (hoping this will allow map sensor to take full control of air mixture). Drove around the block... same behavior.

I unplugged the spark plugs and clicked some photos so you can see how it burns. I noticed some carbon in the chamber (you should be able to see if you zoom in the photo). I tried to pull it out but didn't manage, it dropped in.

one question:
in the photo of purge valve, you can see on the right side of the photo one connector... unplugged. What is this for? I just found it there hanging... (I did not unplug it myself)

 

[marinosg]

Had to do a 12 mile journey today, with no time pressures, so reset my display to km, and to show the instantaneous fuel consumption. Of course, recording them as I drove was not possible, but had to stop at some long-delay traffic signals and wrote stuff down. Here's what I think I remembered.

First, some detail.
2006 Panda 1.2 60hp 137326km
Outside temp 17°C Climate control set to 17.5°C Aircon running
Thermostat seems a little lazy, as it took longer than usual to get to normal temp, on a warm day. (Looks like time to replace the stat.)
From cold start, first few metres showed 25l/100km, reducing quickly to around 15-17l/100km for the first few hundred metres.
Moving at 20km/hr 12-15l/100km, engine still warming up.
Once up to temp:
Off accelerator, back to 25l/100km, which appears to be the maximum it will read.
Slow-moving traffic, 20km/hr 7-8l/100km, 30km/hr 6l/100km
Slightly faster traffic, 70km/hr 4-5l/100km
Average over journey, 5.3l/100km

The average once returned to my normal mpg figure is what I've been experiencing over the last 12 years, so whilst some figures may look thirsty, they seem to be OK, and therefore normal.

I've no idea whether I can record these using MultiECUscan, and create a report or graph, but I may have a look at that at the weekend.

Meanwhile, my advice would be to work on the average only, not instant figures. The instant readout, on any car, is distracting, and potentially dangerous, as it demands attention, when we should all be looking out the windows instead.

this is similar/same experience to mine. I get same reading/measurements.
But, if this was just about readings and measurements, I would not mind at all. The real problem is that I get 150-200 km on full tank by driving within the city - while previously I was getting 400-500.

 

[koalar]

The unplugged connector is just the unused speedometer not needed when the car has ABS