It is hard to explain, but my car (328) isn't smooth at all RPM's. At a steady RPM, like 3500, it will run fine, but will miss about every 20 (total guess) power strokes. It accelerates fine but it is annoying. I have new spark plugs and wires. I did a resistance check on all of them from the inside of the distributor to the end of the extensions and it looks good. The contacts on the rotor and the rotor itself are worn so that may be an issue, but an expensive fix. Could more powerful coils help at all? I have seen a few threads on it but haven't seen any actual tests. Any help would be much appreciated. Thanks! Gene
(Assuming that you have a US version 328) One thing you might try (just to better rule out the fuel side of things) is to unplug the O2 sensor and see if the behavior is the same or different (i.e., when the Lambda stuff is running at a fixed setting).
You may have a spark plug extender going bad. Pull them out and check very carefully. Alternatively, buy a new one and exchange it with one cylinder at a time. Cheap way to find a bad one. Dave
This thread shows a picture of a 328 where the Owner found that the single wire from the O2 sensor was already disconnected -- you'd do the same for the test: http://ferrarichat.com/forum/showthread.php?t=153484
Could be something as simple as a plug extender not properly seated on the plug. I found a couple of mine were a bit loose & that seems to have cured a similar problem - just required a little fettling of the spring thing inside the extender. Also, as has been said, check all your extenders for scorch marks & cracks. You can get the pattern dizzy caps from Superperformance & these seem to work well by all accounts. Another option is it could be the crank sensor is starting to go south - do a search for that & how to test them. Getting into the land of the "horribly expensive" then you are looking at the coil(s) and/or the ECU starting to break down. I.
Not necessarily---they are NOTORIOUS for shorting out to the head---examine them all with magnifying glass on inside and see if htere is any burn indication. sometimes a small hole will be on outside with a black scorch mark at it...replace them all and for added protection i wrap mine with about 3 layers of electric tape or 1 good shrink-wrap coating..... I have had a dozen or more people call me with 308's misspireing and 90% of the time it is the extenders....
