Technical Misfire above 60ish+ MPH

[JSingh1]

Hello,

Trying to sort out the misfire issue some people experienced 1.4 8V grande Punto of a flashing engine light and misfire codes when hitting 60ish+ mph & does shake a little. The engine light goes off once speed drops.

Had a service done on it 4 months ago, and I got the original NGK spark plugs for the garage to use as per the part number on Fiat Elearn for a 1.4 8V.

I changed the coil packs & leads today, wasnt any high end ones but was a brand new Lemark coil & leads. Same problem as before. Scanner showed Misifire on multiple cylinders, a code for each cylinder.

Not sure what to do next? I've heard it can be a timing belt problem, where it's not been fitted properly? It was done before we got the car in January, by previous owner.

MES will not let me carry out a phonic wheel relearn as it says RPM too high. RPM sensor?

So far:
1. New spark plugs
2. New coil pack
3. New leads
4. Oil & Air filter service

Thanks

 

[eeeno]

The reason why phonic wheel relearn is not done may be that the engine is not yet running on its operating temperature. It's wrong, don't do it.

Is it losing coolant somewhere? The engine may be worn. Check compression. Pcv hose leak, but you already checked that thing when changing the spark plugs.

May need a cambelt change? Or did a that problem occur after cambelt change? Then it needs phonic wheel relearn.

 

[JSingh1]

MES won't do anything once it's up to temp either, just says revs are too high.
I don't think it's losing coolant, seems fine. Dirty coolant but fine, lol.

PCV hose should have been checked by the mechanic when they changed the spark plugs, hopefully.

Haven't checked compression & I think the cambelt was changed before I bought it?

 

[eeeno]

You can assume things or you can DIY to know for sure.

You can do phonic wheel relearn even without MES. Just search these forums or elearn material (google it) what is said about adaptation.

Good luck.