General Panda playing up :(

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General Panda playing up :(

mitchk

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Hi Guys,

just wondered if anybody could shed some light or offer any advice to why my 2004 1.2 Panda is playing up.

Problem : When started from cold the engine vibrates a lot as if it is misfiring and you can feel the car hesitating when driving. After a couple of minutes, the car feels much better although still seems to be misfiring. Occasionally the Engine light will come on although does not seem to go into any limp mode. Reading the fault reports 0172 which using the Torque app suggests running too rich and connecting it to the free version of ECUSCAN shows lambda 1 & 2 rich. Car has no problem starting cold or hot and returns 48mpg according to computer.

so far, I have replaced with no change :

Both Coils
Spark Plugs
Leads
Air filter
Thermostat

and have also cleaned throttle body butterfly and ECU connectors.

Oddly, when it throws an ECU error, it is always when idling and after a few days goes off on its own.

I did wonder whether the Panda has an engine temperature sensor separate to the one that controls the dashboard gauge ? this would maybe explain why the car is trying to run too rich ? and maybe not leaning out the mixture once the engine has warmed up.

anybody got any ideas ?
 
Difficult to pin point, but there is a fueling/air issue.

The ECU is detecting it's running rich (or being mislead to thinking it's running rich)
Then it's subtracting fuel from the mixture (upto 30%).
But still not getting a coherent reading from the O2 sensor to achieve a perfect mixture and still reporting rich (no matter how much fuel it removes from the mixture)

As these haven't a Mass Air Flow sensor to give a dodgy report of air entering the engine, I would hazzard a guess it's a heater problem within the upstream O2 sensor.

It happened to our old 1.1 Active, the car started from cold and failed to heat the O2 sensor fast enough, so it tripped into "Open Loop - system fault" rather than closed loop running and over fuelled.

With Torq set up, try starting the car from stone cold (leave overnight) and see what the fuel system status it up to, it should go from "open loop" to "closed loop" within a minute or two.

Other possibilities are a dodgy MAP sensor, though they don't usually give problems.
An intake air leak, (yes it will run lean, but try and overfuel to compensate)
Exhaust leak near the upstream O2 sensor.
Thermostat stuck open causing the ECU to detect a cold engine all the time or a temp sensor issue (but you gauge on the dash/coolant temp within Torq would highlight these)
 
Hi Goudrons - thanks for the reply.

definately not thermostat as car heats up perfectly.

where is the MAP sensor ?
 
As you look under the bonnet, it on the right of the inlet manifold, to the right of the throttle body, but before you pull it, use Torque to check it.

You should be able to log/monitor the manifold pressure and see it change as you increase rpm, think it knows this as Intake Manifold Pressure.

Chased this problem myself and have a new MAP sitting on a shelf as I presumed it was a air measurement problem.

I don't think it's the MAP but the upstream O2 sensors heater.
I don't think it's heating or heating quick enough from cold and feckin' up the fueling, I bet if you run it until the hot exhaust gas heats the sensor enough, restart the engine, it'll run ok until it cools off and you're back to square one.

As the upstream and downstream O2's are the same part, if you have a O2 socket (buy one/borrow one), swap the 2 sensors over.
The upstream (pre cat) sensor output trims the fueling, but needs to work fast, hence the heater element.
The downstream (after cat) just monitors the cat's performance, it's output will not effect the cars fueling.

So if I'm right, the worse you can do is sort the fuel trim out, making the engine run better and perhaps cause a catalyst efficiency fault (but I doubt even that as the ECU knows cat's don't work properly until they are mad hot anyway)
I've never read anywhere what a post cat sensor should read voltage wise, only what is shouldn't read, it should not copy the upstream, ie switch up and down as quickly.
 
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thanks for this - I've ordered a O2 socket

Car is parked in my garage at the moment so will fire if up in next few days and see what the sensors read

thanks for your help and advice
 
ahh yes - I ordered the first one like you - will give it a ago anyway.

have just monitored O2 sensors on startup from cold with Torque app for what it is worth and Bank 1 Sensor 1 volts is +- 0.5v while Sensor 2 sits at 0v

as the car warmsup sensor 2 starts giving an output and after 5mins both read around the same +- 0.95v

will remove both leads from sensors when car has cooled down in case of bad connection.

do the sensor values seem right ?
 
have just monitored O2 sensors on startup from cold with Torque app for what it is worth and Bank 1 Sensor 1 volts is +- 0.5v while Sensor 2 sits at 0v

as the car warmsup sensor 2 starts giving an output and after 5mins both read around the same +- 0.95v

will remove both leads from sensors when car has cooled down in case of bad connection.

do the sensor values seem right ?

They do -- but you need to watch them in real time, if possible -- and from cold. :idea:

If you can do a live data read (which it looks like you can...), you should get something like this (the bottom two lines) -- with the first lambda spiking; and the second lambda doing very little: :cool:



This is with two new lambdas, and a new manicat -- and on my 16v Punto -- but, as Goudrons said: once the engine is warmed up, the first should show lots of activity; and the lower one very little. :)
 
No probs! :)

It's this, using the Bluetooth dongle. Only does engine-related stuff (so I use MES for PAS, airbags, etc.): but ultra convenient -- especially as my iPhone is always in its cradle...! (y)

thanks very much but didn't work with my generic BT module.


I have just had a quick play with the car with the ECU scan program on the laptop.


Lambda 1 - hovers around .9v so is giving a rich output - I have checked this on the graph setting and it does fluctuate I think like it should.


the car also goes from open to closed mode after a minute or so whilst the Lambda 2 stays at Open.


this may sound strange, but a while back I noticed on a few occasions that when I parked the car up there was a bubbling sound which sounded like it was coming from the back seat. Further investigation pointed to the fuel cap. I thought nothing of it and a real long shot but do you think the fuel return pipe could be blocked ? I read that a test for an O2 sensor is to temporary restrict this pipe causing an overfuelling or rich state


http://forums.puntomk2.co.uk/showthread.php?1269-Lambda-Sensors


how would I check for a blocked fuel return pipe though ?
 
ok just an update, but a good one :)

the problem was the purge valve that was not shutting during idle. Have just swapped with ebay bought one and perfect again. Damaged one you could blow through when removed from engine.

symptoms were very erratic and poor running especially when brimmed with fuel. Post O2 sensor was constantly showing rich when idling so ECU was trimming fuel back and leaning out mixture too much - would occasionally throw engine light and give 0172 fault on code reader as was hitting trim limits.

Valve is on the right hand side of manifold with a blue pipe connected to it. Very easy to change but had to buy second hand as new was crazy money.

ah well - kept me foxed for a few weeks
 
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