Fiat Punto 1.2 16V 2004 - Running on 2 cylinders - Fixed #
Posted by Brian Baylis on June 9, 2017, 8:50 am
Year of Manufacture *: 2004 Engine Size and Code *: 1.2 16v
this is not i'm afraid a very technical post as was done in a rush but will have the car back soon to do more in depth testing . the car has had an intermtent misfire when damp but when it arrived had a bad misfire and was warm and no signs of damp. did spray some water around which did nor seem to make any difference removed no 1 and no 2 plug leads made no difference to idle speed when 3 or 4 removed with 1 and 2 unplugged engine stalled . removed plugs on 1 and 2 seemed ok and when plugged into leads with engine running spark jumped a large gap . so replace plugs and leads then disconnected 1njectors in turn with the same results. removed injector rail to find that all injectors seemed to inject fuel for 2/3 cycles then still seem to inject but very small amounts of fuel while this was happening fuel pressure remained constant at about 3.5 bar . p s did check injectors with node light and listened to clicking before removing them
not sure where to go next would injector duration and current ramping help any help would be great as donnt do a lot of this type of work at the moment
thanks Alan Was thinking about that but was getting caught up in the fact injectors seemed to deliver well then very quickly drop of to little flow but that was all injectors. But had all so thought this would /should not cause a 2 cylinder miss fire. Went to do a comp.test this morning and do not have a 12 mm adapter so will have to wait till Monday. Thanks for the reply, seems very quite on here used to come here quite often a few years ago only just re-joined Some times i think as i work on my own there is no one to bonce ideas off and i cann't see the wood for the trees Seem to miss the obvious and it needs fresh eyes to see it for me thanks again
>>removed injector rail to find that all injectors seemed to inject fuel for 2/3 cycles then still seem to inject but very small amounts of fuel <<<
If all the same possibly an ECU strategy to prevent flooding / cat damage ?
Does this log misfire fault codes ?
Remember that if ECU detects a slight regular misfire (which might not be detected by driver) it will stop injection to that cylinder to prevent cat damage, it will then of course be very noticeable!
hi Aidan this vehicle definatley has a miss maybe my explanation not very good but basically has 2 cylinders (no 1 no 2 ) that do not appear to contribute . when i pull off the plug leads or the injectors to those cylinders there is no change in engine speed/sound Allso just noticed plugs are black bot not oily
thanks Alan Was thinking about that but was getting caught up in the fact injectors seemed to deliver well then very quickly drop of to little flow but that was all injectors. But had all so thought this would /should not cause a 2 cylinder miss fire. Went to do a comp.test this morning and do not have a 12 mm adapter so will have to wait till Monday. Thanks for the reply, seems very quite on here used to come here quite often a few years ago only just re-joined Some times i think as i work on my own there is no one to bonce ideas off and i cann't see the wood for the trees Seem to miss the obvious and it needs fresh eyes to see it for me thanks again
well long story short after all the tests i could think of decided to run it for a while and let it get hot . then up in the air with the car to find the exit pipe of the cat glowing cherry red . thought ah that could be the problem then a blocked cat as the internals of the cat were jammed up behind the down stream 02 sensor . so removed the manifold cat just to prove it only to find that it was still the same . then i had a brain wave if i had a brain with no ideas let to try sat and looked at the car thinking the scrap yard is calling As i said did every test and still had 2 almost dead cylinders No1 and N02 so why those 2 a blocked cat would affect all cylinders and i had spark injection fuel compression and timing all ok the one thing that i had not checked was the plug leads as i had not touched them and the car was ok the day before this problem apart form a damp start missfire some days so i thought what the heck swap no 1 and 2 plug leads over And yes it ran perfectly (well as far as a fiat with no exhaust could . A friend of mine had taken a quick look at the car while he was in my garage a couple of days earlier before i started stripping things off and had taken the plug leads of to check them and put them back incorrect but as the car had a bad miss fire from the blocked exhaust did not realise they were wrong and i did not think to check as i had not taken them off . I new all along i was missing some thing simple
on June 9, 2017, 10:10 pm, in reply to "
if i had a brain