super51fan;1978038 said:
I don 't know how come the MKIII crowd is so against FCD. On one hand they talk about the over rich safe factory fuel tuning. Then on the other how the FCD kills engines. Yes you can be stupid with anything. The MKIV crowd suggest the FCD for BPU setup. With your list of mods I think it is a good idea. Btw the black car in sig. page has ran one since 1992.
The reason is, that it is a very destructive tuning item when used in an uneducated or improper way, which more often than not it is. There were a large number of people that did kill their engine in the early days. Those pages existed on the pre-pre-crash forums and mailing lists. The HKS FCD was intended to be used in concert with several other supporting HKS electronics, it deviates the signal from the AFM by a set percentage across the entire operating range. So while there may be plenty of extra fuel to get past fuel cut at WOT, you can encounter other driving situations where the ECU is searching for a more stoichiometric option and the deviated AFM signal can create a dangerously lean condition. So while people may think they have plenty of room to push the envelope when checking AFR's at WOT, they have run out of room in other areas that they are not paying attention to.
And just because you have successfully used the FCD for a long time doesn't automatically mean it is a good idea, primarily due to the inherent risks in using one. To use an analogy, If you hand the average person a chainsaw, and send him into the woods to start cutting down trees, there is a very high probability that he is not going to come back alive. If you give that person some knowledge on the proper way to cut the trees down, the possibility that the person comes back alive improves greatly, but it does not change the inherent risk that person will face cutting down trees. That risk is there regardless. That risk is the main reason we don't recommend using the FCD. Especially when you take into consideration the likelihood of what is becoming the typical MKIII owners probability to cut corners, or not heed warnings when setting up the FCD. It's more productive to dissuade the use of the device to the majority. Those that are left are going to use it regardless of what it said, but hopefully they will do so fully understanding the risks.
Lastly, the MKIV community do not suggest using the HKS FCD for BPU setups. The typically recommended device is the Greddy BCC. It clamps the signal at a set level, unlike signal deviation that the HKS employs, so that the various ECU controls, such as sequential turbo operation are not altered.
