As the title suggests 1.4 MPi 8v, 50k miles, idle is a little uneven, almost like it's missfiring every now and again, car runs perfectly, drives smoothly and pulls OK just the idle is a little annoying, I've read this can't be adjusted but is there something obvious I should check or is it just a trait of this engine ?

I would start checking all the normal things, plugs, leads/coils any vacuum leaks etc. Could clean the MAP sensor if it has one and plug it in to check the readings etc.

1 hour ago, Panther_uk said:

As the title suggests 1.4 MPi 8v, 50k miles, idle is a little uneven, almost like it's missfiring every now and again, car runs perfectly, drives smoothly and pulls OK just the idle is a little annoying, I've read this can't be adjusted but is there something obvious I should check or is it just a trait of this engine ?

 

I wouldn't worry about it, the 1.4MPI engine is an ancient design and they're famous for being tough but a bit rough around the edges.

They have an uneven idle but it shouldn't be really erratic. Mine was far worse when the battery was failing because it put more load on the engine to fight the extra alternator resistance.

 

EDIT: Also check the small vacuum pipe that goes from the rocker cover to the throttle body. And check the large breather hose. They can become perished and affect the idle.

Edited 18 June, 20188 yr by TMB

If I recall correct the 8v is a OHV engine.. Any of my past experience with OHV is that tappets need adjusted quite often to stop rough running (which is more noticeable at idle than when driving) , you had them done? 

 

Tbh I've not seen that exact engine but on most OHV it is a simple job... Time consuming but simple.. Just buy a decent brand of (slider gauges I think they're called) 

 

if if you need anymore help let me know and I'll whip the Haynes out for you.

4 hours ago, taylsy01 said:

If I recall correct the 8v is a OHV engine.. Any of my past experience with OHV is that tappets need adjusted quite often to stop rough running (which is more noticeable at idle than when driving) , you had them done? 

 

Tbh I've not seen that exact engine but on most OHV it is a simple job... Time consuming but simple.. Just buy a decent brand of (slider gauges I think they're called) 

 

if if you need anymore help let me know and I'll whip the Haynes out for you.

 

The tappets on the 1.4, 8 valve mpi engine are hydraulic self-adjusting. It was one of the modifications VW did to the old Skoda engine.

 

A base adjustment is possible but only to be done if the valve gear has been dismantled, or possibly if the head has been skimmed due to gasket failure.

 

https://workshop-manuals.com/skoda/fabia-mk1/drive_unit/1.0/37;_1.4/44;_1.4/50_kw_mpi_engine/engine_cylinder_head_valve_gear/repairing_cylinder_head/basic_setting_of_hydraulic_valve_clearance_compensation/

Edited 19 June, 20188 yr by TMB

Nice feature, I'd never heard of it.... Well chances are it's not tappets then

6 hours ago, taylsy01 said:

Nice feature, I'd never heard of it.... Well chances are it's not tappets then

 

No, it's caused by cam scatter, a result of the cam chain slackening off over time, there's really no need to worry about it, it's perfectly normal.

My sister-in-law had an MPI Fabia from new and it always had that rough idle like a plug was misfiring.