My car has been at the Ferrari dealer for 2 weeks now with them trying to get to the bottom of this never ending CEL P1154. The tech said he changed the plugs because Ferrari changed the the spec of the plugs a while ago and that Ferrari themselves suggested this get done. The CEL hasn't thrown again for the tech, but I know it will. He's taking it for a 40 minute drive tomorrow again. Is it possible a change of plug could sort this? I doubt it.
P1154 is your LTFT hitting the upper threshold - ie: the O2 sesnor is saying there is too much oxygen in the exhaust. I would have thought a bad plug would cause the opposite as unburnt fuel would be dumped into the exhaust. I would say that you either have an unmetered air leak (manifold gaskets?) or the O2 sensor is bad.
Manifold gaskets have been done and the dealer said the 02 sensor is fine. But all along I have thought it was an 02 sensor. Reason being the CEL only throws after the motor is well and truly warm. Is there a way of testing it? Thanks for the info though.
The engine runs in open loop mode until it warms up so that may be why it doesn't throw the code until it is warm. If you suspect the sensor then note the STFT and LTFT on the other bank and then swap the O2 sensors from side to side to see. Afterwards watch the STFT on the other side - if it rises then it stands to reason that the O2 sensor is faulty.
The O2 sensor is looking only to O2 in the exhaust, not to unburt fuel. In case of bad plug or coil, the unburt mixture contains the (unburt) oxygen, which is measured by the O2 sensor and let think the ECU that the mixture is too lean. This is consistent with a P1154 DTC.
Of course, you are correct. However, if the cylinder was dumping enough unburnt oxygen and fuel into the exhaust to trigger this code wouldn't the cat monitoring system have something to say about it? EDIT: It is worht swapping the MAFs to see if it is a case of incorrect measurement of the air flow? Remember at low RPM (which is where this code is tied against) the air crosses the intake manifold.
I'm copying this and sending it off to the tech. Thanks a lot for this info. All I know is that I'm not picking the car up until this is sorted. Cheers
Graham, can you pm me...I want to ask you a few specific question about your car. I had this code before and it took me a long time to get it corrected, but you would not believe what causes it.... I took advise from F-chatter here in this forum, got lucky and CEL has not return....
The time driven and or distance may not entirely effective when trying to complete a monitor to see if there is a fault or not. It's consider a "drive cycle"...O2 monitor are "two trip" cylcle trigger. You can drive it all days and it won't trigger the like, but two trip of 15minutes with knowing the parameter, can easily trigger the CEL, if there is a fault...
I hope you got a good tech working on your car...Driving it that much just to set a CEL seems a waste of time, mileage put on the car, clutch wear, and so on. Sorry for sounding too conservative. LOL I do smog inspection here in CA, and yes, running the monitor (for Ferrari) can be xtremely challenge. But on the other hand it would be a challenge to any type of manufacture car and not just Ferrari, if you don't know the parameter for that specific system. In this case we are talking about O2 monitor...
