Technical Fiat cinquecento 899cc hesitates when accelerating

[Luismigas]

Hello I have a 1994 fiat cinquecento 899cc and when I push the car it can sometimes hesitate or sluggish to accelerate, also have that happening with a fiat punto I have, also from 94. could it be the map sensor ? I noted different wires going into the intake, what other sensors could there be, I know it shouldn’t be an issue from the fuel pump, I also just changed out a the fuel filter, the car starts up and runs without issues, but I am hoping this will be a simple fix and not something too extreme, I hope to restore this car and keep it on the road for as long as I can so any and all help is appreciated

 

[bugsymike]

Any chance an air leak on the inlet side causing a weak mixture and making it stumble?
Can't recall on your model, but is it possible for timing to be retarded a little?

 

[FiatMatt94]

A few days ago I had this intermittently on my 899 Seicento where it was slightly hesitant & sluggish on acceleration although it started & was running ok but with an intermittent misfire so when I got home I pulled each HT lead off 1 at a time, numbers 1,3 & 4 were all consistent with a healthy spark but number 2 was very weak in comparison to the other 3 so I determined it was either a faulty HT lead (number 2) or a coil that does cylinder 2 breaking down so I purchased a new decent set of HT leads & 2 new Bosch coils as I don't do cheap unbranded chinese parts, they only cost me just over £40 & after fitting them which took only 15-20 mins it has completely solved the issue. Also check your spark plugs tips are tight. When you change the coils the leads go in a specific order, so as you see the coils on the brackets mounted sideways to the rocker cover as marked in the picture

The correct order the leads go in as below

Top coil
Cylinder 3
Cylinder 2

Bottom coil
Cylinder 4
Cylinder 1

This is all pretty self explanatory when you do the job as all the leads are different lengths.

 

[timmycm850]

Can I ask if you have E5 Fuel in the car or just E10.