Technical 500C twin air misfire/flat spot

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Technical 500C twin air misfire/flat spot

trippo62

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May 8, 2013
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Sydney
Hi all
I have a flat spot issue with my 500C. The coil packs have been replaced...twice. I drive in manual mode and mostly using the paddles. I tend to drive the 500 Twin fairly hard...even in Sydney traffic (yes, Australia). Here are the symptoms:
- accelerating hard in 2nd gear a flat spot/misfire at about 2750rpm and another at 3000rpm
- EWL flickers on
- accelerating hard in 3rd gear a flat spot at about 2000rpm (doesn't happen as often as the 2nd gear flat spot)

This flat spotting does not occur when driving smoothly or 'normally'. It really only manifests under harder acceleration. Maintaining the hard acceleration when the flat spots occur results in the EWL staying on, the warning "Start/Stop is not available" and the engine running as rough as it can. Pull over, turn the engine off, restart the engine, back to normal.

I usually drive with the Start/Stop feature off (ie engine does not turn off when stopped in traffic) but have experimented by leaving it on lately. No difference.

I use 98 octane fuel (mostly Shell, occasionally BP or Caltex Vortex).

My gear change method in manual mode mimics the traditional manual change where I release accelerator momentarily on gear selection. Habit.

Any ideas besides the "Italian service" remedy suggested on another post. Not that I mind hitting the redline on occasion I'm just not sure that post referred to a 500C Twinair.

Given my driving style should I buy the Arbath ? Should I change my gear change method? Should I not take it to the local dealer and find a mechanic who can fix it ? Surely I couldn't be the lucky recipient of 3 dodgy coil packs in a row from FIAT.

Any ideas the forum has would be appreciated.

cheers
 
Take it to dealer could be coil packs again! Maybe they replaced it with old spec rubbish! By the way, can't really do Italian tuning with a ta as the rev limiter is so low and sudden.
 
Surely I couldn't be the lucky recipient of 3 dodgy coil packs in a row from FIAT.

Did replacing the coil packs previously fix this issue? How long was the car running fine until the issue happened again?

Also, have you owned this car since new?
 
Hi 44sunsets. I must admit the car ran better with the new coil packs for a while. Can't say how long exactly until the flat spot manifest again but it would have been within a couple of weeks from service. First coil packs replaced as part of the recall.

I have had it since almost new. It was a dealer demo. It had only travelled 800km.

I reckon I'll take it back to the dealer I purchased it from for the next check. Last couple of services I've taken it to the dealer where I live (Inner West).
 
yeah I know. My moto guzzi Griso revs harder than this ta. It's still fun to drive though.
 
What about chucking a couple of new spark plugs in it? One might be failing.
 
Two new plugs should be cheap and simpler that rooting around with coil packs. Some VW twinchargers were prone to misfire and the fix was new plugs that were properly gapped. VW diagnostic tools could readily identify the offending cylinder too, so perhaps multiecuscan can do similar with the TA.
 
Hi all

I have a flat spot issue with my 500C. The coil packs have been replaced...twice. I drive in manual mode and mostly using the paddles. I tend to drive the 500 Twin fairly hard...even in Sydney traffic (yes, Australia). Here are the symptoms:

- accelerating hard in 2nd gear a flat spot/misfire at about 2750rpm and another at 3000rpm

- EWL flickers on

- accelerating hard in 3rd gear a flat spot at about 2000rpm (doesn't happen as often as the 2nd gear flat spot)



This flat spotting does not occur when driving smoothly or 'normally'. It really only manifests under harder acceleration. Maintaining the hard acceleration when the flat spots occur results in the EWL staying on, the warning "Start/Stop is not available" and the engine running as rough as it can. Pull over, turn the engine off, restart the engine, back to normal.



I usually drive with the Start/Stop feature off (ie engine does not turn off when stopped in traffic) but have experimented by leaving it on lately. No difference.



I use 98 octane fuel (mostly Shell, occasionally BP or Caltex Vortex).



My gear change method in manual mode mimics the traditional manual change where I release accelerator momentarily on gear selection. Habit.



Any ideas besides the "Italian service" remedy suggested on another post. Not that I mind hitting the redline on occasion I'm just not sure that post referred to a 500C Twinair.



Given my driving style should I buy the Arbath ? Should I change my gear change method? Should I not take it to the local dealer and find a mechanic who can fix it ? Surely I couldn't be the lucky recipient of 3 dodgy coil packs in a row from FIAT.



Any ideas the forum has would be appreciated.



cheers


If it was me I'd be bringing to my dealer to have fault codes checked rather then second guessing what the problem might be, that's what your warranty if for after all!
 
Two new plugs should be cheap and simpler that rooting around with coil packs. Some VW twinchargers were prone to misfire and the fix was new plugs that were properly gapped. VW diagnostic tools could readily identify the offending cylinder too, so perhaps multiecuscan can do similar with the TA.

That's true, but if a coil pack is just starting to fail, there is a possibility that it might run normally for a short time with the new plugs and then misfire again in a few thousand miles, leading you to mistakingly believe the problem is with the plugs rather than the coil pack.
 
Two new plugs should be cheap and simpler that rooting around with coil packs. Some VW twinchargers were prone to misfire and the fix was new plugs that were properly gapped. VW diagnostic tools could readily identify the offending cylinder too, so perhaps multiecuscan can do similar with the TA.

TA plugs are NOT cheap..,:(

BUT they get changed annually with servicing anyway..;)

I wasn't aware it was still under warranty.., :rolleyes:
try ECO mode anyway.. as it'll be interesting to see if the Misfire "moves" within the rev range ( due to load changes within the mapping)

do let us know what you find.., (y)
Charlie
 
I have pretty much an identical problem with my 2012 TwinAir and it's been at Fiat since May trying to be fixed. It was at 1 dealer for a couple of months and I gave up on them after they told me I should just take it to an auction and take the loss on the car even though it's still under dealer warranty, I've since taken it back to the dealer I actually bought it from. Car seems fine in eco mode, just broken when accelerating hard in second and third in non-eco. I've had the car given back to me a few times after it been told it has been fixed but same problems occur each time.

So far they have changed:

Spark plugs
Coil pack
MultiAir unit
Head gasket
Spark plugs
ECU

and it is still broken. I'd love to hear if you do manage to find the cause as they are stumped.
 
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So far they have changed:

Spark plugs
Coil pack
MultiAir unit
Head gasket
Spark plugs
ECU

and it is still broken. I'd love to hear if you do manage to find the cause as they are stumped.

I assume you are only using 98 ron fuel. Using low octane fuel would quite possibly cause the higher performance tune to mis behave. If you are using exclusively 98 from a single source maybe try getting your fule elsewhere for while.
My VW has an ECU tune and it specifically requires 98 to function properly.
 
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