SimonRHC Posted January 26, 2009 Share Posted January 26, 2009 Hi Chaps, Having convinced the nice man next door to buy an alfa 156 2.5 the dam thing is not playing the right tune. well when i say the "right tune" it's not hitting the high notes. It revs and pulls (sounding amazing) cleanly round to 5.5k rpm where it just starts spluttering and smelling rich. (during a drive by with me on the curb) yesterday it was fine, today not so. it has coils on top of each plug so i'm assuming the HT leads arn't HT (we couldn't see any tracking sparks). could the spark be weak? Could it be the extra juice at 5.5k is quenching the spark? could the spark be weak? what would cause it to start spluttering at 5.5k? We have checked the airflow meter and it's not that. he is going to run it up to 5.5k in the morning (what finer alarm call) in nutral just to see if it splutters under no load. the thought being that the revs will be the same but there wont be a lot of cold petrol vapor hitting the spark because they'll be light pressure on the accelerator. we found that there was a split in the concertina tubing between the airflow meter and the throttle valve. maybe at 5.5k the valve timing changes and the extra air being drawn in is causing the split to open suddenly turning the mixture very lean? I'm worried that unless we can fix this we might seace being mates and he won't have as much free time (and imunity to cold) when my caterham needs to get through it's MOT this time around! Cheers Si Link to comment Share on other sites More sharing options...
Steve, Carol and little Cl Posted January 27, 2009 Share Posted January 27, 2009 Any air entering the intake system after the mass air flow meter is unmeasured air, and can cause a multitude of problems, especially with the fuelling. It may not be the cause of the problem you've got, but before you go off chasing unknowns, sort out the split tubing, otherwise you could well end up peeing into the wind for quite some time. Once done, you can eliminate that as a cause of the problem, should it still be present. Something else to note....if, for whatever reason, the engine misfires at 5500rpm, you will more than likely be able to smell the unburnt fuel. This does not necessarily mean that the engine is running rich and causing the engine to miss, it may well be one of the symptoms of another problem. On the other hand, it doesn't rule it out as a cause either (sorry if that hasn't helped). Good luck, Steve Edited by - Steve, Carol and little Claire on 27 Jan 2009 08:44:59 Link to comment Share on other sites More sharing options...
SimonRHC Posted April 25, 2015 Author Share Posted April 25, 2015 Two tanks full of Redex infused 4 star completely cured the problem. And i though it was an old-wives tale! Link to comment Share on other sites More sharing options...
SM25T Posted April 25, 2015 Share Posted April 25, 2015 Did it really take 6 years though ?? Link to comment Share on other sites More sharing options...
6speedmanual Posted April 26, 2015 Share Posted April 26, 2015 Ans since when did a 156 run on 4-star? Link to comment Share on other sites More sharing options...
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