Factory ecu

[neil_jdmr]

I Have been reading a fair bit into how the factory ecu works in comparison to the stanalone range and have found out that when the standard mazda ecu detects knock it retards the ignition timing acting as a safegaurd.
 
Stanalone ecu\'s dont do this function for the obvious reason as your tuner has set it up correctly he will have compensated fuelling with the timing demand.
 
But im now wondering if this safeguarding measure is whats causing my boost to drop off2-4psi after 5k. Its deffo not fuel cut as thats a sharp kick feeling similar to the car cutting out, but it does feel like the timing is adjusted back as its still pulling but not as much as it should and the engine note isnt as aggressive as it should be.
 
 
I will mention this to pip see what he thinks when he maps my recently purchased pfc and hopefully shake hands with full boost to redline:D

[BlitzBoy]

yes when it retards the factory ECU also pulls back boost when knock is detected down to 7psi

[neil_jdmr]

Funny thing is though it still did the same with the factory backbox??
 
 
Although when it was rebuilt a new refurbished turbo pack was fitted which i have now found out is from a 99+ car.
 
The peices seem to be falling into place now.
 
 
My money is on the factory 8bit ecu is retarding timing because of knock, due to the newer spec turbos producing more boost.
 
 
Bring on the pfc:wiggle

[BlitzBoy]

you have 99 spec turbos wont make it produce more boost, the factory boost solenoids control boost. If you getting knock its due to something else either the fuel mixture is now to lean . Are you getting the heat warning light flash at all?

[neil_jdmr]

No heat light, and never seen it even at WOT,
 
It was also happening with the factory exhaust and just filters,
 
 
So ??,   Fuel filter maybe/ injectors/ ecu itself

[leon]

From memory if you get knock the heat light on your dash will go crazy with the standard ecu! Are you sure you just dont have a problem with the rats nest/solenoids that controll it as your making boost up to around 5k (rough area for the changover to 2nd turbo.) or even a leak on the intercooler pipes etc?

I think the factory turbo\'s controlers are sprung to 5psi by default (so if you dont have a way to controll the arm it will only reach 5psi)

[RemarkLima]

I thought the factory ECU didn\'t light up anything for knock, only the Power FC\'s do that as there\'s no facility to retard knock.

But then it could just be a gammy knock sensor.

[neil_jdmr]

Leon, Its deffo not that as ive been on with this for months now and just about everthing pressure/vacuum related has been double checked and /or replaced.
 
Remarklima, I too was under the impression that the factory ecu didnt flash up any lights for knock, only the pfc, as that setting can be selected on the commander ( as can max injector duty ).

[BlitzBoy]

The reason I mention heat light if your CAT has collapsed and causing the ECU to retard.


ps 7psi is the wastegate spring pressure you cant go lower then that in boost, if you do then you have a boost leak

[neil_jdmr]

The cat has been changed for a known good one as the original had collapsed and 7psi sounds about right as the second comes on strong to 0.8bar then tails back to 0.5-0.6 which is about 7 psi.
 
 
Sorry but my gauge is in bar

[BlitzBoy]

yep sounds like either a solenoid problem causing the boost to drop off or the ECU is retarding the ignition and cutting boost due to knock. Once you get the Apexi in and Mapped , Pip will be able to tell if you have a solenoid problem

[neil_jdmr]

If the ecu is retarding ignition due to knock, what variables cause knock on a good condition near standard motor (only filter and a backbox) ??

[neil_jdmr]

Just a quick update!!!!
 
Been to wgt and and yes the factory ecu was saving the engine by retarding ignition and cutting boost, Pip explained to me that i was infact getting boost creep due to the backbox/filter/99spectwins ?? somehow. So as the boost was spiking to 13-14psi the standard ecu flapped and reduced power.
 
The good news: i now have full glorious boost till redline and beyond, a solid 0.8bar and she pull like an absolute train. A TOTALLY different car.
 
Celebrated by embarrassing some guy and his chick in a black 07 plate 350z GT on the way home, and i do mean embarass :-)

[connor66]

Nice one Neil, pleased you got it sorted
Gary

[pearl_rex]

how did u get this sorted out mate? suspecting i have the same problem