Technical 1.2 engine misfire cured(finally!)

[steveras57]

Hi all just wanted to share this in the hope it might help someone else out!
I have had my 500 for 9 months and in all that time it has had the "classic" idle misfire/stumble that manifests itself by excessive vibrations felt through the seat and can be seen by the air filter box vibrating back and forth at tick-over!.

I had tried everything i could think of as follows! new spark plugs (iridium!), new coil pack and leads, new map sensor, new throttle body, all vacuum lines checked, intake rubber replaced, timing checked, ecu parameters reset(many times,) two tanks of 99 ron fuel with injector cleaner put through!, fuel cap checked for sealing ,all electrical connectors in the engine bay cleaned with contact cleaner and more i have forgotten! nothing worked!! Even checked that no spark plug was crossed threaded like it one of Pauls cars on love 500 you tube channel! nothing!
In the end just by chance a mate was talking to me and said have you swapped any of the injectors as if one sticking or failing the cleaner wont make any difference!.
No says i. so he lent me a spare injector rail he had! took an hour to swap it on Monday (quite easy job worst part was releasing the "quick release" fuel rail supply connector!) very easy to break the tabs!..
Put it all back together and first turn of the key i knew it was different! revs went up then settled tick-over at 1000rpm as she warmed up ,then dropped to 800 r p m steady as a rock with no shuddering through the seat and air box just tremoring evenly!
FINALLY ITS FIXED!.
So my advice would be if you have changed the plugs, leads,, and coil pack do the injectors next before you do anything!!! else ,might save you a whole lot of time and aggro! in the long run!.
As you can get a complete fuel rail with injectors and wiring used online for between £45 &75 quid id change the whole thing in one go! rather than individual injectors ( unless you can positively identify the problem one!) dont forget theres probably a lot of dirt and debris down there so clean it out as best you can before removing the old rail(it takes quite a bit of tugging and pulling as the old seals have probably been there a LONG time!) when putting the new rail back in i sprayed wd 40 around the holes and put a VERY LIGHT coating of red rubber grease on the lnjector "O" rings!, it requires a "FIRM" push to get the rail back in, as all four need to locate and go back in at the same time! go slow and double check at least twice (useful to have a good L E D torch with you to see properly!).

p s my car is a 2012 with 84 k miles on her!

hope this helps someone out there who might be suffering similar frustrations to what i was!
stay safe all!
best regards
Steve

 

[Ralf S.]

Touch wood... but I've never had any injector problems on anything.. and several of my cars have been over 150k, with a couple close to moon-shot distance (225,291 miles, although that's not important).

I regularly feed the cars a supplement of home-made fuel system cleaner every 2 or 3 fill-ups, using whatever random solvents I have to hand.

Usually this is kersone (aka "Turpentine Substitute"... which is not white spirit, nor "Eco thinners" etc.) and if I'm feeling creative, I'll mix in some Propanol, Acetone (use Hammerite thinners, or just buy a litre of Acetone from eBay) or Toluene (ditto eBay). I've even used B&Q brush cleaner in the past... since it is "petroleum distillate" .. no idea what kind, but it's blue and can dissolve paint.. It's going in..

Anyhow.. 250ml of brew per tankful of fuel may be extra-useful now that benzina is full of Ethanol.. since some solvents (Propanol particularly) can dissolve separated/condensed water, which is a by-product of having extra Ethanol in the petrol.

The only yardstick I've got to measure whether it works or not is I once sent some injectors to be ultrasonically cleaned, since that car was suffering from what turned out to be a sooted up throttle position sensor. The before and after report came back that the injectors were running around 96-7% efficiently, with one down at 94%. After the clean they were 98% and 96% respectively... so, it seems like they weren't in too bad shape, even at 150k.

I dunno if the brew helped or not but anyhow dissolving gum/varnish doesn't seem like a bad thing and it's easy and not tooooo expensive (certainly if you brew your own, rather than use off-the-shelf proprietary stuff, which is usually 90% kerosene anyway, but with a dye in it to make it look saucy.


Ralf S.