Question on newer cars with high leakdown, FI problem?

This is a general answer but, on the 5.2 motronic you have one ECU controling both banks of a 355 and fuel maps that are used have limits to the fuel that is injected based on various sensor information. If you were running too rich a mixture and the 02 sensors could not correct it the CELs would come on.
The 355 engine problems are more related to header and valve guide failure. All factory headers should be changed to an aftermarket part, NEVER replace with a factory piece. The valve quide problem only effects certain cars('95 and some '97 and '98) corrected with steel guides in mid '98, might be poor quality meterial or poor installation(or both). This is fairly general answer, do a search on 355 valve quides and headers you will find a ton of info. Regards, Vern

 

I would lean(no pun intended) on the answer that it is fairly difficult for electronic FI systems to allow 1 or 2 cylinders to run so rich that OBD part of the ECU would not catch the malfunction. On the electronic systems I suppose you could have a bad injector but, if it gets real bad the 02 is going to try to adjust the mixture via its reading from the exhaust on the offending bank(1 ECU on 5.2 but 2 02s) and it eventually will probably turn on the CEL because the ECU can't bring the fuel mixture within it's pre-programed parameters. That is what is good about the computer contolled fuel and ignition systems of modern cars they "see" problems long before they get serious, in most cases. As you probably know you could have a bad carb throat on a 308 weber system that could cause a rich cylinder and maybe not notice it and have no warning (no monitoring system) Did that help? Again this is fairly general. Regards, vern

 

Yes, a fuel injected Ferrari can run rich on just 1 cylinder (e.g. failed or incorrect fuel injector). Worse, it can run lean leading to catastrophic damage.

No need to guess, though. You can pull your spark plugs to instantly discover if you have such a rich/lean condition in any cylinder(s).

http://www.ferrarichat.com/forum/showthread.php?p=136079421#post136079421

 

NO Not possible.



We are talking about US spec Ferrari's.

If the engine is running correctly in every way the cats are much of the time running very near their max operating temp. To not do so would be throwing away HP and Ferrari did not build or tune the cars that way. One of the reasons car makers have been able to make more and more power since the intro of cats is that cats have been able to take higher and higher heat without either overheating or degrading faster than federally mandated life spans. That has allowed tuning the cars to higher levels. The F40 was the first production car with metallic cats. That kind of performance would not have been possible without them.

That is exactly the reason so many people have slow down light problems. One cylinder not running well, slight mistiming of a cam (3 degrees is enough to do it) etc can cause a slow down light easily.

Also when 1 or more cylinders is not running well they often do not burn all the oxygen they have available. When that happens the O2 sensor richens the mixture and you have China syndrome.

 

I will ammend the previous post to say I have seen many cases where an entire bank or entire motor was running so badly that sufficiant exhaust heat was not available to get the cat hot enough to warm up and hurt itself.