Technical "Flat spot" on acceleration

[Old Man Jitsu]

Hi guys. Bought a little Panda 1.2 Young a couple of months ago. As I always do when buying a used vehicle, I serviced it, had the cambelt changed, changed the gear oil and anti freeze. The little car has been a joy, but for one problem. At first, it tended to die underfoot while pulling away. First thought it was me, but some of my employees said it did it with them while driving as well. Took it for diagnostic and they said the battery terminals needed to be changed. I realized since that it only seems to do that when the aircon is on. So will take it to a specialist for that.

However, another problem that bothers me is that the acceleration is smooth, but not uniform. This happens whether aircon is on or not. It doesn't starve or die but you can feel the power comes and goes when accelerating....difficult to explain. The vehicle has proven to be quite dependable and economical but I travel 50km daily through rural South Africa and I am concerned that it might get stuck with me at some point if I don't get this sorted.

I have changed the fuel pump and filter (in tank) as well and the problem persists. Vehicle still has the catalytic converter in as it only has 108000 km on. As mentioned it does daily long distance driving and the last bit I was heavier on the loudpedal, thinking something might 'burn clean' so to speak.

Any advice appreciated

 

[koalar]

take a look at the spark plugs and post some pictures


would tell use/you how its burning.

Quite a few misfires/flat spots under acceleration are due to the gap increasing or wrong plugs fitted previously

 

[Old Man Jitsu]

take a look at the spark plugs and post some pictures


would tell use/you how its burning.

Quite a few misfires/flat spots under acceleration are due to the gap increasing or wrong plugs fitted previously

Thank you, I will check and post pics, but it was doing this before the service as well, and I checked the plug gap myself before fitment. Thinking maybe I should change the plug leads as well...

 

[timmycm850]

Hi all.

If its a euro6 engine and the flat spot us just on light throttle. Then its due to the eu emissions requirements of liw emissions.

Best thing and is a popular thing to do here in the UK is go and fit some Iridium plugs as this reduces the effect.

Give it a go.

In south Africa what is the fuel type normally available to you.

Tim

 

[Old Man Jitsu]

Hi Tim. Here at the coast it is 95 Octane Unleaded. Not sure how to identify a "Euro 6" engine....

I've thought about changing the coil and plug leads, might as well then get the iridium plugs as well and fit them...

 

[MrMagoo]

Was it behaving properly before the cambelt change?

 

[Old Man Jitsu]

Was it behaving properly before the cambelt change?

Well I hardly drove it before I serviced it and had the cambelt done. Initially thought it might be a "VVT" issue, but then realized there is no "VVT" on this engine.

Do you think it might be a valve timing issue?

 

[MrMagoo]

Possibly. You need to be absolutely spot with modern engines even if they don't have VVT.
And if you are going to do your own maintenance or diagnostics than you will need an OBD tester.

 

[Old Man Jitsu]

Possibly. You need to be absolutely spot with modern engines even if they don't have VVT.
And if you are going to do your own maintenance or diagnostics than you will need an OBD tester.

Proper knowledgeable technicians (apart from the stealers) are a scarce commodity here in SA.

Actually that might make sense. One night just after driving a mountain pass an error code came up. I took it for diagnostic and they said it overheated (only happened once and no permanent damage) If indeed the valve timing is incorrect, it will cause overheating under these circumstances as well...

Funny enough. I have a Autel diagnostic machine, but it cannot communicate with the Panda. I have a servicing and minor repair shop, so use the Autel quite often, and this is only the second vehicle it won't communicate with.

 

[koalar]

drive ability faults have many causes nobody can tell you change this and it will fix your problem. Although you may guess right via luck

what year is the car

if you listen carefully to the exhaust note from the back of the car. post a YouTube is helpful

is it even or every now and then a pop or a regular pop sound

no vvt sounds like an older engine to me

we have nothing to go on

at the moment its anything to do with ignition, fuelling or compression. We are shooting in the dark. I could guess everything to do with those three systems but it would be pointless.

injectors
crank senor
plugs
leads
pump
relay
head gasket
burn valves
MAP sensor
coil/coils
battery
alternator
blocked CAT
accelerator pedal
throttle body
piston rings
cracked melted inlet manifold
O2 sensors
and more

we need to start somewhere. I normally start by looking at the plugs. We aren't there so posting a picture is the next best thing

 

[timmycm850]

tell us how old your car is as it might help diagnosis

Easy to try the iridium plugs first.

Tim

 

[Old Man Jitsu]

It is a 2012 Panda 1.2 and it has done 108000km so mileage is quite low as well. There is no "pop" while driving, but I have noticed that if you floor it (overtaking another car or such) the engine does get louder under load (but not in relation to speed)...I put that down to the throttle being wide open?

 

[jrkitching]

Was it behaving properly before the cambelt change?

Well I hardly drove it before I serviced it and had the cambelt done. Initially thought it might be a "VVT" issue, but then realized there is no "VVT" on this engine.

Do you think it might be a valve timing issue?

Posts reporting rough running / low on power after a cambelt change appear frequently here.

The camshaft pulley isn't keyed, has no markings and thus the timing is infinitely variable. The procedure for changing the belt is quirky, and most independent garages outside the dealer network won't know it, or have the necessary timing tools to do it properly. Improvising without the correct tools is commonly tried, with varying degrees of success; some get away with it; others have the kind of issues you're describing in this thread.

It's more serious on the VVT engines (you can do real damage if you're not careful), but the non-VVT unit isn't immune from this sort of thing.

 

[Old Man Jitsu]

Thank you for the advice guys as well as the list I can start with. I will start with checking the valve timing at a Fiat specialist and work from there. Much appreciation. Will keep you posted.

 

[Old Man Jitsu]

Sorry to flog a dead horse. I am starting with some easier stuff seeing as I co-own a tyre and exhaust shop. Getting new plugs and plug wires today. Has anybody here "de-catted" a A118.4000 Panda? I see it has one O2 Sensor above and one below the cat, will I have problems with engine lights and limp mode?

 

[koalar]

Sorry to flog a dead horse. I am starting with some easier stuff seeing as I co-own a tyre and exhaust shop. Getting new plugs and plug wires today. Has anybody here "de-catted" a A118.4000 Panda? I see it has one O2 Sensor above and one below the cat, will I have problems with engine lights and limp mode?

illegal here in the UK

people have put the punto sporting catifold on and it just moves the power band up the revs range

if you suspect its blocked remove the top O2 and take it for a drive. I very much doubt this will be your problem.

you can run without either O2 sensor. I dont think I have tried without both. Yes it will put the engine light on. yes you burn more fuel with the top one disconnected. It uses default safe values but not a limp mode.

throttle pedal and head gasket are common for flat spots but without something to go on we can only keep guessing

compression test
live data recording
photo of spark. plugs

something

 

[DaveMcT]

The 1.2 60 is a "safe engine" so if you mess up the timing or break the belt no serious harm gets done. However its very easy to set the new belt one tooth retarded.

There is no need to loosen the cam pulley wheel.
White mark the timing positions on cam wheel and lock the crank with the special tool.
Simply fitting the belt and tightening the tensioner will pull the cam one tooth out of alignment.
Reft the belt one tooth away and retention the tensioner. The marks should now be correctly aligned. Remove the crank lock and box up the job.

 

[timmycm850]

Not sure which way you are going. Take some of the advise above to help you with flat spots. If you want to go down the modifying route its a bit difficult to.help from the UK as we have differing regulation.


Tim

 

[Old Man Jitsu]

So interesting development. When ordering the new spark plugs, I looked it up as a NGK BKR5EZ, the only one listed for the A188 engine. However the vehicle has a ZKR7A-10 fitted. "Eureka!" I thought and ordered 4 new spark plugs of correct spec, but the 'correct spec' has 14mm thread and head had a 12mm hole

 

[A3jeroen]

Isn't it supposed to take DCPR7E-N-10?

All in the manual which can be downloaded from FF.

gr J