Z does not accelerate

Vicster

Not exactly...

Yes, there were codes and the codes were MAF related. The throttle bodies are not really the issue. It's the buildup in the throttle bodies that cause the problems. As a couple in this thread mentioned doing, cleaning the throttle bodies also works to fix this issue. So what's the root cause? Probably a few things but we're leaning towards a combination of oil output from the PCV and oil/junk from the filters.

So what's the problem with the ECU? And as you stated, why can't the ECU tell they are shut when they shouldn't be? Well, this is my take on it: The ECU does see that there is a problem but not with the TBs. When the car is started and begins to idle the ECU sees two non equal outputs from the MAFs from each intake bank. It begins to prefail the MAF sensor that appears to be reporting a non-normal idle air flow based on how much air should be allowed through a closed TB. It also decides to put the car into a limited power mode at this point (though this part is odd and doesn't seem to happen all the time during the prefail but is consistent once the CEL is on and the code is fully thrown) as I would imagine it is trying to prevent damage to the engine with different intake levels to the manifold. Eventually the code is fully failed and CEL comes on. So why? I suppose the ECU is programmed to think a sensor has failed before the TB, which sorta makes sense to me.

So, is there a fault component in the TB? No. Plain and simple, no. It's just that Nissan doesn't have a clean up procedure for this issue and just replaces the entire throttle body - which is somewhat normal in this industry these days.

This is basically why the next step for me is to get a good set of catch cans and to not use oiled filters anymore. Plenty of good dry filters (even in some of the nicer CAIs such as the Stillen)...

__________________
-Chris

'13 Z34 Touring Sport | ARK GRiP CBE | Stillen G3 CAI | AAM HFC | UpRev | 20mm Z1 Spacers | StopTech Drilled/Slotted Rotors | StopTech SS Lines