First Time Datalog

[BR1JZL]

Hey all, this is my first post here and I've tried to read as much as possible before making a post (will still probably get flammed).

I bought an '05 Mazda 6 MPS (or Mazdaspeed6) about 4 months ago.

I have the thing fairly stock performance wise, other than a 3"CircuitWerks downpipe.

I have also completed a list of preventative maintenance items:
Cleaned Intake valves and intake manifold w/ Walnut Media and new OEM intake manifold gasket
Run Subaru Upper Engine Cleaner (we don't have Seafoam readily available in Aus)
Changed O2 Sensors
Changed RMM to Damond
Changed Rear and Front Brace Diff Mounts
Changed Thermostat
Changed Transfer Caps
Changed spark plugs (running ITV20)
Done compression test
Cleaned EGR system
Coil stretch
Timing Chain, VVT actuator and race bearings have all been changed (owner before)

For some reason the car struggles on the performance side and randomly has an aggressive feeling knock (generally over a KR of 2). I took it to Mazda, who after hooking it up to their software, couldn't see any issue, but said it felt like there was no boost.

I have also done a boost leak test and exhaust leak test, and fixed any issues, but yet I have grannies flying past me on the freeway still.

I am hoping the datalogs pros can have a look and let me know if there is anything out of place? I couldn't get to 6,500 RPM as I ran out of road, but it is WOT in 3rd gear from 2,800RPM to 5,700RPM.

I have attached a data log using the Torque App (haven't been able to purchase the AP yet), and have it graphed here:

https://datazap.me/u/br1jzl/first-da...og=0&data=5-12

[Pu Manchu]

Torque is a horrible way to datalog on these cars, the resolution is nightmarish. I'll say what little I can guess from this poor log, but you really need a tool like Accessport or Versatune to do anything with this platform.

15-16 psi boost, expected.
AFR 10:1, pretty expected.
Boosted air temp 75C, roasting hot, wouldn't be surprised to see this heat cause loss of power and knock retard.
Fuel pressure dipping into the 1400s, over 1600 is considered safe. your car probably doesn't have upgraded high pressure fuel pump internals and the already rich AFR combined with the heat and knock retard putting additional strain on the fuel system.

Assuming the data is accurate, I wouldn't push the car in these conditions.

[BR1JZL]

Thanks Pu Manchu, the Autotech HPFP and Cobb AP are next on the list, was just trying to get it to stock performance (the car was running the same before the DP as well).

[5doorsoffury]

You could put a gallon or so of e85 in to a full tank and that should help stop the knock until you get this sorted out.

[BR1JZL]

Can you run e85 on stock setup (no flex tune etc)? We use 98 Octane in Australia as pump fuel.

Also in regards to the fuel pressure, is it that it shouldn't dip below 1600 in WOT conditions, or in general?

[BN00249]

Originally Posted by BR1JZL Can you run e85 on stock setup (no flex tune etc)? We use 98 Octane in Australia as pump fuel. Also in regards to the fuel pressure, is it that it shouldn't dip below 1600 in WOT conditions, or in general?

1st) Dont need a flex fuel sensor. The e85 is only used to minimize knock, not for any performance gain.

2nd) Wot you should never dip below 1600. direct injection hpfp's pressure varies from idle 430'ish up to 1800+ at wot.

Ps.
That downpipe shouldve never been installed until you upgraded your hpfp

This forum is FULL of info that has been collect over 10yr with thousands of people sharing their knowledge of this platform. It still is the go-to place for most things. Read, read, and keep reading if you want to keep your car and keep it running well.

good luck

[BR1JZL]

also, I have searched, but can't seem to find, is their a guide on "how to read datalogs"?

[Dubcnea]

Originally Posted by BR1JZL also, I have searched, but can't seem to find, is their a guide on "how to read datalogs"?

Never seen one.


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[MSMS3]

Running a 3" downpipe on stock tune and with stock hpfp is a big no-no. It requires a hpfp upgrade. It's downright unsafe to run it as you are. It also requires a compatible tune.

You are not only getting dangerously low fuel pressure, but if your data log had high enough resolution (refresh rate) it would probably be showing nasty transient boost spikes as high as 22 psi or more. Also, due to the poor resolution of Torque, you may be getting transient fuel pressure drops much lower than what you are seeking. It only takes a fraction of a second to lean out and destroy an engine. The engine's ECU will try to compensate for low pressure by increasing the length of time the injectors stay open, so as to maintain a safe AFR. It can do this only up to a certain point. If you were logging injector pulse width, you would see it widening considerably when pressure drops. This is dangerous when it reaches the point that it can't keep up. And is not good for the engine, regardless, because the extra fuel is not being atomized properly and may be pooling up on top of the pistons.

1. Do not go wide open throttle any more untij you upgrade the fuel pump internals and get your AP (or Versatune) and have compatible tune for the extra flow from that mod. It will raise boost by at least 2 psi with a good tune - more like 18-19 psi and do so safely only if tuned for it.

2. Get the pump internals, AP or Versatune right now, load a dp compatable safe tune, learn to log and consider getting a custom tune from one of the excellent e-tuners here.

[BR1JZL]

Hi all, thanks for all the responses, I have ordered the Autotech HPFP, so should be here in a few days, but it’s also left me broke until next pay cycle :/. On the plus side, that’s the first time I’ve actually gone WOT, but will be taking it easy in the mean time