Ok so  with a nearly 20 year old car it could be anything.. or lots of little things taken altogether - or it could be one thing - need some input ^^

 

fuel filter replaced, air filter replaced, timing chain replaced, some nice bosch exotic metal sparkplus, good oil, good filter

 

No fault codes at all

 

Pulling up onto the highway is not a problem - the car will pull its weight just fine going into high revs without stutter in any gear and keeps going very steady

Starting is never an issue - 1-2 turnovers and its running

 

Sitting their idling the engine will have the mpi shake as usual  with the addition of some variety - the rpm gauge wobbles around and so does the engine

- 830-870rpm -

 

Putting a brick on the gas with the car stationary applying a static load to get it into the 2000-2500 range   that same wobble to the rpm count is present and is magnified with the wobble to the rpm count increased in stroke so to speak

 

Under load driving  there is no perceived engine rpm variance..

 

 

 

Edited 8 October, 20187 yr by Goss

Vacuum leak, check the servo hose first.

thnx sepulchrave - I did have a look at the vac lines but there was distraction going on at the time ( ball, kid )  will have a poke and feel round again this weekend without

 

 

My sister-in-law's 2002 reg 1.4 mpi had that shake from new. She kept it for 15 years and traded it in for another Fabia. 

yes but  shake as in a steady shake  or a shake with exponents 

 

it has been a while since we drove this new  but  I think remember her going a good bit steadier on the rpm count

 

 

A regular shake like it was running on 3 cylinders. On the move it pulled OK. I was not looking at the rev counter but I felt it as a passenger

Edited 9 October, 20187 yr by edbostan

Lol k   that does sound a little like ours Ed..

 

It has been a while since I took an interest in engines - and now it just bothers me I can't figure out what is keeping it from running as smooth as I thínk it used to be. The mechanic where stuff gets done on the lift just tells me  it's running,no fault codes,  it starts fine  it hasn't stalled on you ever, fuel mileage is good - don't let it bother you because these things are just the way they are..

Came close to purchasing a used fab III combi recently (funny how in all this time none of the competition has filled the niche the fab combi takes up)  - and taking a critical look at how things stand with our fab I and made the decision to enjoy it just a bit longer if we can manage.

Dusted off my toolset, Haynes book and obdII and  enjoying my gearhead neighbours' commentary while I poke and prod at the problem - none of which is really narrowing things down but is widening the search lol

 

Short of poking a scope into the combustion chambers one tip I got was  to fuel op on 98 instead of 95 and see how she runs - if the engine runs smoother its probably carbon buildup.

The buildup is never even and it can make the air-fuel mix / compression ratio different between cilinders which can make the computer try to compensate for this which makes for the wobble in rpm..

will try that and report back ^^

 

Edited 10 October, 20187 yr by Goss

I did not like to mention it in case I upset her. She had it serviced regularly so I am sure the dealer would have picked up upon it. She was a low miler of only 2000 miles per year and a typical lady owner. 

Sounds like someone I know ^_^  Hér car's computer told the tale of her total average speed being somewhere around 15km/h lol, with about 1000km per year travelled..  Prime candidate for carbon buildup but  hers ran just fine and smooth for a good decade and a half till she finally traded it in. Only once had a major issue due to a faulty alternator which basically toasted the battery - of course this had to happen just when I was driving it..

 

Well its not the first tale of shaking mpi's I have found and heard about..   

Mine likes to work out the engine mounts nice and good as well but adds a shudder every couple seconds

Will inspect áll the vacuum hoses again, have a looksee in the throttle body, and when I visit the garage next time for fitting some winter tyres I'll ask him to check the fuel system pressure exactly  - just to be sure its still in the operating spec, chuck in some more injector cleaner and then  follow my mechanic friend's advice - just accept it lol

 

 

Sounds like a 1.4 MPI AQW to me ! Mine's just the same and always has been

Lol k thnx nipedley  For this week incl in real life that makes three encounters with fellow fab1 Combi owners who did heavy head nodding at said quirk I am just about ready to accept it.. 

 

if it aint broke don't fix it   don't go pulling at loose threads  and all that   she is nearing 20  no use poking her all over if no faults show mileage is good  and nothing is leaking out or falling off or knocking kaput.

 

Some due diligence in poking a camera down the sparkplug wells for giggles  and running my eyeballs and fingers along all vacuumhoses and such   then onto winterizing her for the coming one I suppose.. 

 

Thanks for the perspectives everyone =]

Compression pressures?

 

I had 1.2 mpi running idle on 2 cylinders, and on revs every cylinder. It pulled ok but idle was horrible and engine shaked a lot. Middle (#2) cylinder had 5-6bar and #1 and #3 over 11 bar compression pressures.

No fault codes - pinging or failed ignitions would definitely throw those. Did try fueling up with Euro 98 - she ran nicer on the stuff - engine ran  well more buttery I would call it ^^ but  the rpm's  were no smoother..