Is 18.1 psi boost, stock?

[Noah99]

Just used Versa Tuner for the first time and with a couple hard pulls I got 18.1 psi boost with 1748 fuel rail pressure. Just bought the car and I want to make sure that 18.1 psi is okay. Looking forward to your replies.

PS- I'm looking to change the intake to corksport and also a corksport HPFP. I just want to make sure everything's fine and dandy before hand.

[Pu Manchu]

18 stock isn't a disaster outside of low RPM under heavy load, bad AFR, high BAT, knock, etc. a datalog would tell a better story.

[MSMS3]

If AFR is not lean, pump pressure stays no lower than 1600, and the boost tapers to 15+/- at Redline, I’d not go crazy. But stock boost should be 15.5 or thereabouts max.

This makes me suspect the car has previously been modified. An aftermarket downpipe will raise boost to 18 psi even on stock tune. And, it is not safe without a compatible tune.

[Noah99]

Thank you for the respectful replies.

To my knowledge the car has zero modifications, the 2nd owner gladly boasted about that before I purchased the car.
Also I stupidly didn't monitor the air/fuel ratio.
I'll do another run soon and I'll post the log here, since I have no idea what these numbers mean.

Also, What does BAT mean?

[Noah99]

Attached is a csv. with a couple hard pulls. Looking forward to reading your replies!

Min/Max Boost (PSI) = -12.4/17.5
Min/Max Actual equivalence AFR= 0.629/2.000
Min/Max Fuel Rail Pressure= 403/1736
Min/Max Engine RPM= 701/6250

Min/Max Desired fuel rail pressure= 292/1669
Min/Max Desired equivalence AFR= 0.631/1.009

[Noah99]

Also here's a csv. of my car idling afterwards.

[whatsabrooklyn]

hey, this may help a bit

Ultimate Guide to Parameter Monitoring?



BAT mean boost air temperature.

this could be a decent reference for ya

A Noob's Guide to Tuning Acronyms


also try to do pulls over 3k rpm for engine safety (didn't read log so maybe you did)

[Vansquish]

OK. Let's chat about datalogs. Imagine that you're where we are. You've been asked to remotely help figure out things that might be going on with someone's car. Datalogs are obviously going to help. The question is: what kind of datalogs?

Well, we need logs that show whatever problem that you're trying to have us diagnose. That means, if you're having problems under boost, we need datalogs showing behavior of the car under boost. If you're having problems under idle conditions, then we need to see idle behavior of your car.

We all have limited time though, and asking someone to sift through data from a log that is more than 2400 lines long is...unrealistic and difficult. It's also frustrating for those of us inclined to help you out.

Here's what I would recommend:

1. If you're having problems or concerns with your car's behavior under boost, take a standard WOT log. That means, put your car in either third or fourth gear, start datalogging slightly below 3000rpm, push the pedal to the floor and log all the way past at least 6000rpm. Then stop the log.

2. If you're having problems or concerns with your car's behavior at idle, take an idle log that replicates whatever issue that you're concerned about. It doesn't need to be thousands of lines long.

In short, hone the logs so that they show what you want to show us, not everything under the sun and then some.

Furthermore, when you datalog, you should make sure to capture at least the following parameters, but DO NOT include desired fuel pressure and desired AFR.

Accel. Pedal Pos. (%)
Actual AFR (AFR)
Boost (PSI)
Boost Air Temp. (° F)
Calculated Load (Load)
Coolant Temp. (° F)
HPFP Act. Press. (PSI)
Inj. Duty Cycle (%)
Intake Temp. (° F)
Intake Valve Adv. (°)
Knock Retard (°)
Long Term FT (%)
MAF Voltage (V)
Mass Airflow (g/s)
RPM (RPM)
Short Term FT (%)
Spark Adv. (°)
Throttle Position (%)
Vehicle Speed (mph)
Wastegate Duty (%)

[Noah99]

Thank you for the correction Vanquish and whatsabrooklyn. Here's a new log, recorded from 3rd gear at about 2800rpm to 6300rpm. I tried to add everything I could from your list Vanquish, but VersaTuner wouldn't allow me to add more than 16 data points.

I'm looking forward to your replies and criticisms!

P.S. My primary interest is the AFR. I suspect my car is running lean. (Spark plugs had a white haze)

[Noah99]

I'm sort of lost here. Does anyone know how to read the air fuel ratio? If not, who should I send this file to?

[Bertospeed3]

the way your afr is being logged requires a little math for me to be familiar with. Take your afr values and multiply it by stoich afr (14.8?).

So in line 30 of your log, your afr is showing 0.865
0.865 x 14.8 = 12.80 AFR - this is leaner than i would be comfortable with. You would like something starting with 11.xx

It starts to get more rich as your boost tapers down but i'm not seeing any red flags tho.

Granted, i'd wait for people who know more than me to chime in lol just figured id give me two cents

[Jeff23spl]

isn't there a place to switch units from metric to imperial. Yours is in lamba.

If you are limited to 16, i would pic those:

Accel. Pedal Pos. (%)
Actual AFR (AFR)
Boost (PSI)
Boost Air Temp. (° F)
Calculated Load (Load)
Coolant Temp. (° F)
HPFP Act. Press. (PSI)
Inj. Duty Cycle (%)
Knock Retard (°)
Mass Airflow (g/s)
RPM (RPM)
Short Term FT (%)
Long Term FT (%)
Spark Adv. (°)
Throttle Position (%)
Wastegate Duty (%)

Discarded ones:
Vehicle Speed (mph) (Probably needed for virtual dyno but...)
Intake Temp. (° F) (you can just note the ambiant temp yourself)
Intake Valve Adv. (°) (higher level of tuning...)
MAF Voltage (V) (Needed with flow when you do a maf cal but flow is enough for diagnosis)

[Jeff23spl]

here is it with correction, i used lambda 1=14.7

[Noah99]

Originally Posted by Jeff23spl here is it with correction, i used lambda 1=14.7

Thank you for the log correction Jeff! I'm mostly interested in the AFR since it seems my car is running on higher than stock boost. BTW, do you still want me to log another run with the 16 metrics you posted above?

Also, how can we tell what's a dangerous or inefficient AFR?

I know my car has an aftermarket hybrid TurboSmart BPV/BOV, (from the previous owner), but I doubt that effects the boost levels.

[Jeff23spl]

from the log it isn't that much high but i don't know exactly what would it be stock reading.

when i look at your air flow isn't that high,,,

the 50/50 valve is just half bad but nothing to rise boost, it just make it rich between shifts.