Technical Uno 999cc hesitation problem

[smokeme]

I have a friend with a mk2 uno 999cc fire injection (1993 i think), he says that it has a hesitation/stumble around 3-4krpm. It's got new plugs,leads, timming belt,fuel filter, fuel pump and coils (one was cracked and caused misfires)

anybody have any guesses, i haven't seen the engine yet but will this week, i was thinking something was installed wrong or not installed since he said it was there before maintenance was done and it's still there.

does it have an o2 sensor?

 

[Louie Bee]

does it have an o2 sensor?

Hi Smokeme,

Yer - there is a Lambada sensor on FIRE IE .

 

[smokeme]

Hi Smokeme,

Yer - there is a Lambada sensor on FIRE IE .

Thanks, at least i got one reply

 

[Sav_M]

Hi Smokeme,

I'm running a 999 ie FIRE Uno just now and had a hesitation a few months ago.
My problem ended up being with the Lambda/O2 sensor, but was the last thing I tested.

Symptoms were similar to what you describe, plus it was very rough and lumpy until warmed up.
After changing the probe I reset the ECU and drove more gently for a few hundred miles. Runs very smoothly right through the rev range now, and ok when cold.

Sav

 

[Chas Uno]

Might be a fuel starvation problem? Check fuel pump and fuel filter. Possibly a coil breaking down as well? ECU?

I've only had carburetor Uno's so I can't offer much more advice - sorry

I'm surprised you didn't slap on a turbo to this engine like you normally do

 

[Chas Uno]

Just re-read your post Smokeme and realised that you've already changed what I suggested :bang:

Maybe a dodgy distributor? Stepper motor on the SPI unit? Maybe even something like valve clearances?

Best of luck with sorting it out.

Chas

 

[smokeme]

Just to clear something up, i've never seen this engine even though i've driven the car a few times. The car has a very low mileage so i think the valve clearances are ok.