(T) bravo 1.2 16v misfire, pls help

Hi all,
been having a problem with my 2001 1.2 16v bravo, its stated misfiring under load so changed coilpack, leads and plugs, didn`t cure it so had it scanned where i work ( garage/motorspares shop) no faults stored but ignition was retarded when engine was revved, changed knock sensor, which also didn`t cure it,... cam belt needed changing so changed that while double checking timing so know thats ok, nearly pulling my hair out now...i know fueling isn`t a prob coz its lobbing the un burnt fuel into the cat and backfire aswell so looking forward to replacing that soon, just wondered if anyone could throw some light on my problem, wondering if the ecu controling the ignition timing could be at fault...
many thanks...

try changing oil and filter, and spark plugs (check for any signs of oil on old ones)

cheers for the reply, oil and filters where changed months before the misfire appeared, and plugs changed when i changed coilpack and leads
as the first step to track down the misfire, plugs looked a nice toastey
colour so reakon the prob lies elsewhere... also changed crankshaft sensor
now as well and still missing under load...but still not eng man light or fault codes stored GOING MAD!!!!!!!!!!!

I would try a resistance test on the injectors next and a compression test.

thanks for reply, found a written off bravo in a breakers so off today
to get the injectors out of it, if that fails then i`l dig the compression tester out and cross my fingers, one of them probs ya can`t track down...on one hand it looks electrical ,then on the other hand it looks mechanical( no fault codes etc), thanks again mate

Still banging my bloody head, changed a very dirty throttle body today
but still that nasty misfire shows its ugly face. compression test ok, nice high figures and even across the cylinders,...only thing i did notice i took fuel pump out and gave filter a clean off, when i put it back togeather and stuck the ignition on to check for leaks. it seems to take forever for the fuel pump to pressure up and shut off, from turning the key to shutting off takes 7 secs...not sure if this is just a fiat thing or my pump is at deaths door, can anyone shed some light on this

Has the ECU error light not come on at any point. Do you have a spare fuel rail perhaps the pressure regulator is not 100%
Always a chance the fuel pump could give you jip I suppose.

if fuel was a little restricted then weak mixture would give poor detonation,
Are all air pipes ok, no splits etc?

Cheers for reply guys, nope no fault codes/ light at any point which makes me think its got to be mechanical...had it on two different fault code readers one of em being a snapon , might give a new fuel pump and fuel rail ago nxt week...putting new clutch in it as well as thrust bearings eaten it self.. thanks everyone for the help...

O2 sensor in exhaust, can go wrong without red warning light.....!

cheers mate, lambda sensor did cross my mind but was counting on the fact no warning lights came on , but if you say it might not switch light on i might stick it on the emission tester at work, just to count that out...will be so happy when this is sorted....more time to play with my sierra sapphire on wet roundabouts..

I have the same issue with my 1,6-16V (Palio).
Misfiring at idle, 10% more fuel consumption, black exhaust etc.
No red warning light.
I changed coils, plugs, leads, fuel + air filter, used injection cleaner etc. all to nothing.
Emission tester at local garage showed nothing wrong....!!!!
Went to an official Fiat dealer yesterday, car was hooked on Fiat Examizer Computer: car's ECU had stored one fault: bad O2 sensor.
So that's what I'm going to change next week.

Good to hear someone beat the horrible misfire problem...the prob with mine is at idle its fine, no misfire then as soon as you load the engine your driving down the road like a learner driver... doesn`t matter if engines hot or cold/ weathers hot or raining

let us know if that helped

Misfiring in a modern ECU equipped engine is almost always ignition or fuel injection failure, due to bad sensor(s).
So you have to be a computerfreak to read the ECU or you have to go to the dealer to have it done.
I did the last, took less than 10 minutes and was free of charge!!
Did you go to a Fiat dealer already with your misfiring problem?
If you didn't, I suggest you do, have your ECU read by the Fiat Factory Examinizer computer, it's the easiest way to solve the problem!