Originally Posted by
LTPC
The car has done 138000km. I did run a Cobb stage 1 map A month ago and saw boost up to 16psi but I guess something could’ve come loose since. I wonder if it’s the 3inch intake messing with the hpfp?
I can't think of any way for the inlet to mess with the HPFP pressure. I run a similar setup myself - OEM airbox, high flow filter, custom turbo inlet pipe. Your MAF sensor is still in the OEM housing by the sound of it, yes? i.e. MAF sensor and high flow filter are in the OEM housings? That won't introduce any issues in and of itself.
I'm thinking the HPFP pressure relief valve might be in the early stages of failing. I don't recall OEM tuning ever exceeding 1700PSI, but yours is peaking at over 1700 and then dropping back by 100PSI. A stage 1 cobb tune can see 1750PSI on the OEM HPFP but should be steadier than that, and you are on OEM tune. If HPFP relief valve fails it will fail to hold pressure - in early stages I imagine you might well see unexpected variation in HPFP pressure.
The other thing occurring to me is that you aren't reaching wastegate spring pressure of 14psi. The OEM 2 port boost control solenoid bleeds pressure off the wastegate actuator to keep the wastegate closed. With the solenoid bypassed or held in the spring pressure state your boost should reach close to 14 psi. EBC allows the wastegate to be closed longer so boost rises further than 14psi. Fully functional it allows boost to rise to 16 psi or more. If you EBC stuck in the open state I'd imagine overboost conditions more than under.
14psi minus pressure drop across the TMIC with EBC failing to keep the wastegate closed might account for 12psi and no higher.
There are some additional perameters you could log : HPFP commanded pressure to compare against actual pressure - what ECU is aiming for vs what's actually there. I think there may be some similar PID to log for boost or MAP. I usually run my logs using MAP (manifold absolute prressure) rather than boost pressure. MAP will measure 12psi boost as 26PSI = 14PSI atmospheric pressure + 12 PSI boost.
My BL with a stage 1 tune and similar mods (TMIC and inlet) sees 32PSI max = 18PSI boost.
I would be suspecting the HPFP relief valve is early stages failing and EBC solenoid fail - possibly there is a boost leak as well. At 4000-4500 RPM there seems to be enough wastegate duty to expect exceeding 14psi, but it's actually 2psi under spring pressure.
I'd check all hoses, including wastegate actuator hoses, and also confirm your bypass valve has a gasket in it, and the gasket is in good condition.
I'm far from an expert, so there's a bit of edjumacted guessing going on here, but that's what I'd be looking at now, based on the _theory_ I know.
HPFP relief valve suspect
EBC suspect. If EBC dead and stuck in spring pressure state, won't exceed 14psi and won't respond to wastegate duty cycle signal.
bypass valve gasket suspect
Last edited by Nexus; 06-07-2018 at 08:36 PM.
"Blue Meanie" 2007 Aurora Blue MPS 3 - 18x8.5+44 SSR GTX01 - 235/40R18 Michelin PS5 - 3.5" ETS TMIC - CPE stg 2 mount - HKS/CPE BPV - 2XS inlet - 2XS short shift - Corksport turbo manifold - HT 98 octane tune - Leather/Aluminium handbrake - Momo shifty knob - 7" touchscreen - JDM Mazda Retractable dashtop screen assembly - Bespoke Raspberry Pi Android based GPS/Carplay and instrumentation - 36AH reserve battery and C-TEK isolator - TEIN Street Advanced coilovers 1" drop - Superpro bushings - 220Kw/410Nm.
"Lipstick" 2013 Velocity Red MPS 3 - 18x7.5+48 Enkei RPF1 -225/40R18 Federal RS-RR - CPE TMIC - COBB inlet - CPE stg 2 mount - COBB Stage 1 98 octane tune - COBB shifty knob - 2XS short shift - 2XS turbo manifold.