hello everybody,


my Fiat Stilo 1.6 looses power during fast acceleration on 3rd 4th and 5th speed between 3000 to 4000rpm. Missfire alarm has been received for cylinder 4 and after reset for cylinder 2 so far. engine alarm self resets from time to time. engine works fine at any other rpms or when accelation is not "fast".
temperature indication was indicating below middle position for some time and occationally flactuate for no reason. temperature sensor was changed.


from the trip computer i noticed that instant fuel consumption drops to --.-- (zero) at the same time engine looses power, so i believe they are related.


any suggestions ?


thanks in advance

If you're picking up error messages then it's most likely to be an electrical problem rather than a fuel problem.

I'd check the coils, especially if #2 and #4 are connected to the same coil.


If the two cylinders are connected to the same coil, you can swap the coil for the other one and see if the problem switches to cylinders 1 and 3 instead.

If there's an ECU fault instead, the problem will stay on the coil "position", rather than move with the coil itself.


Ralf S.

thanks for your reply

tha fact that the varius problems arise only under specific conditions ( hard acceleration around 3000 to 4000rpm ) gives any clue ? the car works ok for slow acceleration.
is there a case that power surge causes the problems ? can a faulty sensor give such kind of problems/power surges ?

Impedance. If the coil is faulty it will have a higher internal resistance than normal... so under load the coil will be receiving current (c/o the ECU) more quickly than it can get rid of it.

If you accelerate more slowly then it can still shift the current it's getting (to the plugs) but probably at the expense of a lot of heat in the coil. Heat increases resistance, so the problem might be worse when the car has been running a while.

If you swap the coils over it's an easy (free) test to be sure.


Ralf S.

I once had something similar with my Alfa GT jtd.
Sudden "stutter" and the fuel gauge going crazy...than suddenly everything OK again, very annoying, and of course no codes..
Turned out to be a bad (burned) connection at one of the injectors....the fuel gauge got it's earth from the injector connection as well...

thanks for your replies,


as you said it appears to be an electrical problem, with some sort of short circuit. the problems increased the last days, giving false high temeperature alarms among other things.


i took the car to my mechanic to have a look. I will let you know what he finds.

Dear friends,


my mechanic suggested it was an ecu problem, and we changed it.


car started ok, but after 2-3km i had the same problems (not as much as before). missfire for cylinder 1+4, reset, and then missfire cylinder 3. furthermore temperature indication although is fine at the begining at some point it jumps to maximum and then fall back again.


the temperature reading on dashboard is the same the ecu reads ? or there is an other sensor for the ecu ?
the ecu we change was a used one. is there a chance somehow we damaged that one as well ?




any suggestions ?