hello everybody.
in advance sorry for bad english (not my main language)

i have a fiat brava 1.6 1996 manual trans.
iv got it almost 1.5 years now, and since i got it i had a little hesitation problem that i couldnt solve in anyway.
(leads, coil pack, plugs, everything is new and been working fine)

a few days ago i got the injectors out, took a carb cleaner, made a 3v connector and took a syringe housing or what every you call it,
and cleaned all the injector one by one.
put all togather back into the car, and since then the car hesitates on accelertion very badly sometimes when u press the gas on 3rd gear it jump like a kangaroo and straightens up only on high rpm.

iv chacked all injectors for resistance, and all shows more then 15ohm.
the injector light was always off.

plus, i took the car to a car injection repair shop and we checked the fuel pressure, valve pressure. but the mechanic didnt find anything.

please help me i feel so stupid because i made the hesitation even greater, till now the car did a great job didnt break at all.

Check the tube from manifold to the MAP sensor on the firewall, clean it and if it was full of crud, look at the sensor itself.

If it behaves itself on full acceleration but hesistates on partial, it could be the lambda.

partial throttle goes very bad, ill check the map tube and sensor can i clean the lambda?
or the only way is to get a new one?

something weird iv noticed.
when i disconnect the lambda sensor, the warning light doesn't show,
and nothing changes, seems the car doesn't know about the sensor?
my question is will disconnected lambda trigger the warning light?

It should, alteast when the engine has warmed up as it has no feedback for the mixture (water temp sensor? they're separate for dash and ECU).
On full throttle it should bybass the lambda a bit, thats why I asked about it earlier.

Do the plug look like rich/lean/good mixture and similar on all cylinders?
Have you checked the airfilter during your ownership?

the temp sensor works fine, i think. (btw the lambda was replaced by a new one)
still the same problem.
the temp it shows when warmed up is stable right under the half.

iv checked the plugs few days ago they looked like its running rich (plug look bit black)
any idea what can be the cause of it? the hesitating problem is only when driving, when i stand in place and rev the engine, it goes all the way to the rev limiter with no problems at all.

Idle Air Control valve ( IAC)

If the lambda is unplugged, it should go with predefined values from ECU, which shouldnt be too bad.

As for IAC, shouldn't it only affect idle rpm? While driving the MAP should account for all air coming in with the Throttle position sensor.

Try unplugging the throttle position sensor and see if it gets better?
ECU should estimate the position from MAP, lambda and engineload in that case.

A bad or dirty IAC valve affects drivability a lot!
A new one from Ebay is inexpensive.
Also the throtlebody is probably dirty with build up carbon and oil sooth, so cleaning the inside with carb. cleaner may help as well.
Our Palio 1,6-16V suffered almost the same problems as the OP describes, after cleaning the throtlebody, and a new IAC valve, it runs like new...

this is just amazing in a very bad way.
First of all i unplugged the TPS and the car goes alot better, beside the dead zone the throttle has with no sensor, and its not very smooth, but with full throttle the acceleration is just great!!! no hastation.
then i ordered a new TPS from Ebay, installed it and BOOM the stupid problem is back again, mid range RPM hesitating sometimes, full throttle hesitating also. its a bit better with the new TPS, but ALOT better with no sensor.

Did you thoroughly clean the throtlebody inside..??
Take the IAC valve of, and clean it and it's seating and bores as well.
http://www.ebay.nl/itm/Wynns-Air-In...ssories_Car_Care_Cleaning&hash=item43b4bfaf0d

i got a carb cleaner, ill clean the whole throttle later, ill post results tommorow

same s***, cleaned the hell out of the throttle body, seems it got a bit worse then before, the idle now feels not so smooth, the revs are stable no problem with them.
this is very weird the car is alot better with no throttle pos sensor, the new one i got is better, but it didn't solve the problem.
can this be that the ECU is somehow defective?
what any other sensor can couse a problem like that?
temperture sensor? maf maybe? or the intake air temp sensor?

Before changing any sensor at all, have the ECU read at a Fiat dealer....

Back to basics?

Spray the intake manifold from the throttlebody to the joint on the block with brake cleaner or similar to determine if there are leaks in the intake side (also spray the MAP tube, watch the exhaust manifold for fire).

Possibly run new groundcable from block/transmission to the ECU (ecu chassis bolt should be good enough).
And maybe from battery to chassis and to the transmission (Ive done this as mine were corroded, and mine is made in -99, bit more salt and water in Finland I assume).

im about to kill my self. this thing is Driving Me Crazy.
i went to the scrap yard few days ago to try and swap the maf + ecu engine temp sensor.
came home, changed both of them, nothing spacial happend, then i decided ill reset the ecu, so i took the - of the battery for an hour, then started the car for a warm up.
two days later in those two days the cars is driving with the same problem.
today i got home and took the ecu out to open it and see maybe there is a defect that i can see with my eyes. took the ecu in my hand and what i see?
the ecu is from a TIPO called iwf 13.
i guess the last owner changed it idontknow why.
so the question is can it be the problem that i was looking for all this time?
if i get a brava ecu and put it will it work properly? Another thing, wikipedia shows that tipo got 90 hp 1.6L engine, and my brava is 103hp, i assume the ecu isnt the same on both cars? Opinions?

I.A.W.-1AF.13 from Marelli/Hitachi on the manual versions (23 for automatic).
I've seen brava quoted both for 90hp and 103hp on parts sites, but atleast here I haven't seen or heard about 90hp models.

Are you sure the lambda isnt a cheap low quality one? Maybe take it from scrapyard for testing?

Checked the intake for leaks?

Would it be possible that the fuelpump or fuelfilter (mk1 so it has one infront of hte rear wheel) is causing pressure fluctiations -> the injected amount of fuel changes.

please read again what i wrote, my car now has the iaf 13 that says Fiat tipo.
but my car is fiat brava.
my fiat brava is 103 hp as far as i know.
but the ecu in my car is from a tipo 1.6 that has a max of 90hp in any 1.6 engines.

I.A.W.-1AF.13 is in mk1 brava/bravo/marea, also cant say about swapping them over as I have no idea what kind of antitheft tipo had. My guess is just compression ratio/geometry so the tipo ECU should learn the engine.

Brava should have Fiat CODE system. If you swap another bravX/marea ECU into it, you will need the ECU, the Fiat Code box with the reader and the master key for reprogramming your blue keys into it (or just blue keys if you use the donor key with the ignitionbarrel)

Haven't owned a Tipo, I only know the chassis is pretty same.

Did the OP ever get to the bottom of this??? I think my car has the same issue? It's a 1.6 8v tempra I.e engine.