Technical A weird problem, as usual..

[VEEDUBBED]

Hello everyone, been a while..
Right, I got given a 2011 fiat panda 1.2 8v off my cousin recently.
The car was awful, usual Cam beltoff by one tooth discovered whilst I changed the belt, along with a full service. Car was fine, timing spot on after using the proper tool kit for the vvt 1.2 8v motor.
When I gave him the car back no check light was on and no fault codes stored, as I previously mentioned the car went very well.
The problem arose a few days back, whilst overtaking, the car suddenly lost power and the check lite lit whilst he had the car running on lpg.
After interrogating the ecu I get a constant error code P0303 cylinder 3 misfire.
Cancel the code, restart the engine and the car idles normally UNTIL I put it in gear and move off, it immediately goes on 3 cylinders..
Right, work done so far:
Changed sparkplug.
Changed coil and leads twice.
Changed injectors for known good ones.
Changed vvt solenoid
Checked ecu/pins.
Nothing, same bloody code appears as soon as I drive off.
This problem isn't present whilst reversing the car, only in foward gears.
The fault code points to injector 3 open circuit but I know that no.3 injector pulses, spark also present on 3 cylinder too.
I can't workout why it's always cylinder no.3, after clearing the dtc it always pops up.
The car is also fitted with an lpg instalation direct from the factory, same thing though, switching to lpg the the engine runs on 3.
Hot or cold engine, same.
Forgot to mention that this other code is flagged: P0203 open circuit on 3 injector.
Sorry for the long post guys.
Any ideas?
Cheers.

 

[varesecrazy]

Weird indeed....

Even more weird its on driving forward

As a basic diagnostic..

Spray the Exhaust manifold with Water..
It will go Chocolate Brown..almost black

Start car..let it idle.. does #3 branch stay Darker for longer?

 

[VEEDUBBED]

Hi,
Good call, I'll try that next time I can get the car at my cousin's place 70kms away.
Extremely weird one this and I've seen many..

 

[irc]

Is this possibly a phonic wheel relearn issue?
Think I read something similar about a panda with timing belt slightly out running OK, when corrected it threw unexpected errors until phonic wheel relearn was done.

 

[VEEDUBBED]

Done it twice already, even changed the phonic wheel's sensor.
Car ran perfectly, no issues at all then bang, lost power whilst running on lpg and now this dam issue popped up.
One thing I noticed is that as soon as I've cleared the two codes present, both saying the same thing really, the engine starts and idles normally, rev it up all you like without any load and it's perfect, put the car in gear and move it a few meters bang, engine reverts to 3 cylinder running with check lite lit fixed, no flashing.
Put it in reverse and the dam thing runs with no misfire..

 

[irc]

Very puzzling.
Only other oddball thing I've seen is to clear learned settings and do the 3000rpm thing.
That was on a Panda with strange habits (random spluttering, down on power) but no codes though.
Nothing that I can think of that would cause one injector to shut down. (Except a damaged loom, and it wouldn't be this consistent)

 

[VEEDUBBED]

And the fact that it does it on both lpg (four different injectors hidden above the starter motor..) and running on petrol.
I've tried a spare injector connected up to the 3rd injectors plug, with the engine running, dam thing pulses so that excludes the wiring from the ecu to injector.

 

[irc]

Very strange.
Like you, don't see why only injector 3, and only when in gear.
Vague thoughts....
Does it go onto 3 when putting the clutch down, putting it in gear, or actually starting to move?

If you start it in gear with the clutch down, what does it do?

Could it be the movement of the engine and a break in the loom? That doesn't show when not moving?

Other than those, I'm baffled at the moment.

 

[VEEDUBBED]

Yeah, me too.. baffled..
If the car is started in neutral, no problem and you can rev it statically till the cows come home.. lift the clutch nothing revs fine.
As soon as the car is moved in first after a few meters, bingo it reverts to running on 3 cylinders.
Start it in gear with clutch down, same thing, revs fine and no check lite lit. Move the bugga and it goes on 3, petrol or gas makes no difference.
What I can't fathom is the fact that the same problem is present on both lpg and petrol which are two totally separate systems which both have separate ecus and injectors..

 

[jackwhoo]

Check out the main battery ground wires, especially connection/crimping to body terminal

 

[The Panda Nut]

Sounds to me like a wheel sensor must be involved. I should have a very careful look at all of these and see if anything is loose cracked or broken. These computer controlled things have a mind of their own and i know from experience you cannot totally rely on what the readouts say as the whole thing is the sum of its parts not the total. However silly this seems, what else is there that will do anything other than BAS EDD hand brake and hill holder.

 

[Herts Hillhopper]

…As soon as the car is moved in first after a few meters, bingo it reverts to running on 3 cylinders.

What I can't fathom is the fact that the same problem is present on both lpg and petrol which are two totally separate systems which both have separate ecus and injectors..

That suggests it’s not an engine management issue but something related to the movement sensors - ABS, traction control, ESP etc. Broken sensor wires or dirty/corroded connections cause all sorts of odd interactions between the various computers and, if not a ‘preprogrammed error’ may not lead to warnings or error codes. Try a methodical check of each connection on these, maybe?

[Edit: I see The Panda Nut and I posted same thought at same time!!]

 

[VEEDUBBED]

Well, small update..
If I rev the car stationary in nuetral all good, revs to 6000 rpm without issue, press down the clutch pedal and the bastid engine won't rev past 4000 rpm.. let the pedal up and it revs again with no engine light on either..
Is there a micro switch on the clutch pedal??

 

[The Panda Nut]

Yes on a lot of cars there is a switch sensor on the clutch pedal. It is part of the anti stall system / emissions system. It certianly sounds like a prime suspect.

 

[VEEDUBBED]

Ok, thanks for clearing that up.
Time to get my head under the dash and investigate further.
I'll get back with updates.
Thanks everyone so far!

 

[VEEDUBBED]

Right then,
Managed to get to the car this morning early.
Friday I disconnected both lpg and iaw ignition/injection ecus so I connected both back on to the car, started it, all fine no engine check lite lit.
The car is in an underground garage so it's under load to get out, first try in first no problem, pulled out without hesitation, backed back in and tried again, bam.. back to three cylinders..
Disconnected the brake switch thas virtually impossible to get at, let alone even see the bloody thing, nothing changes, same as before the only difference being is that the rev limiter to 4000 rpm has dissapeared because the switch is disconnected.
Always the same misfire codes given by the obd software, always number 3 cylinder injector open circuit.
Checked the abs wheel sensors on both front wheels, both look fine and no dash abs fault lite lit on dashboard display, abs also works fine but engine check lite remains lit.
Could it be a possible faulty vvt camshaft unit?
Vvt solenoid is brand new.
Start it and idle is fine, as soon as it sees a whif of load, 3 cylinders.
Getting a bit fed up with the fu$$King thing now..