[SOLVED] Throttle/Boost Cut/Misfire on Partial Throttle?

I wouldn't dismiss this connection as being a possible problem. But there are no obvious signs of damage. The reason I say this is because the retention mechanism inside those female pins may not be as secure as they look.

Have you plugged this connector back in since you have started diagnosing? Is the problem intermittent or dependent on variables like engine or outside temperatures?

Can you monitor your Throttle Duty cycle and compare it to your throttle position and APP?

 

I cleaned out the connectors for the throttle body and the MAF, in addition to cleaning the MAF itself. The issue persists after cleaning and reconnecting.

I'm going to try and do this next. One thing that I realized was this only really seems to happen in boost. I suppose doing the obvious check for hoses and stuff should be in order, but I'm really trying to think why this issue is very easy to replicate and only seems to happen under partial throttle with boost.

More troubleshooting to come.

 

Alright, I added Throttle Duty Cycle to my datalogs and got 2 more instances of the issue happening.

Datalog 143 (Normal):

Video:


Datalog 144 (Slight throttle issue):

Video:


Datalog 145:

Video:


Datalog 148:

Video:


After seeing datalog 145 I kind of my throttle body and/or connection, however datalog 148 almost makes me wonder if it's potentially pedal related as well. From what I understand the pedal is electric so swapping another one in its place should be easy in theory. Really struggling to wrap my head around all of this...

 

From my understanding:

Accelerator pedal position data goes TO ECU.
Throttle Duty cycle is ECU command TO Throttle body
Throttle Position is the actual position that the sensor is reading on the throttle plate/valve.

Since your system goes rich when the problem occurs, I am going to say that your ECU is commanding the throttle body to open, but it is struggling to stay open at times. Either there is resistance or something is broken. Boost pressure will create additional pressure on the throttle plate, especially at low throttle opening positions (high plate surface area).

Based on the data, I am diagnosing it as a failing throttle body.

I would make sure your throttle body is clean with no obstructions. With the throttle/butterfly plate visible (IC boot removed), You can power the car (Ignition position 2, Key on engine off) and watch the plate move in the throttle body. I believe it does a sweep when you power the car as a self calibration/check system. You may also be able to control the position with your pedal (depends on vehicle).

Before you stick your fingers and try to move the plate by hand, make sure you disconnect the throttle body connector. Although it is not recommended to move the plate by hand, you may consider it, you should feel if there is a change in resistance as the plate opens and closes.

Even if you don't find anything strange in the above diagnostics, I would still consider replacing with a used throttle body. If it is in fact the problem, it won't be a large expense. This type of failure is not common on these cars.

Just note that I am using general knowledge and information that you provided from the diagnostics.

Good luck.

 

Log your calc load.

 

All of my logs contain "Calculated Load (Load)" if that's what you're referring to.

Used OEM throttle body has been ordered! It will likely be some time until I can install it, as I don't have access to a garage, but I will surely update this post with the results.

Here's also a bonus pic of the wiring before it goes inside the connector. Someone from NATOR recommended I check it. It looks good for what it is, so that's what led me to pull the trigger on the throttle body.

 

So it is. Have you checked to see if you're hitting cutoffs in the tune at all? This stinks of tune issues.

 

What do you mean by cutoffs? I checked the logs and nothing looked out of place aside from the parameters I clipped in the screenshots. All the full logs are attached via link though if you want to spot check!

 

He is referring to events where the ECU may "cut off" power via spark or fuel. Sort of like a fail safe, in case it has trouble reading critical sensors.

 

Ahh, I see. Well I'm open to any possibilities, although my tune hasn't changed since August of 2020.

Here's a screenshot from above with STFT and Spark Adv. Although they are changing, I'm still not sure the throttle body is acting as intended, and those two parameters seeming reactive rather than the other way around.

 

Who tuned you?
Do you know how to check your tune safeties as far as load throttle close and fuel cut goes?

 

I'm tuned by DramaTuned who was the first person I sent the datalogs to. He said he was probably the APP sensor, so that's when I started investigating all those parts and connections.

I don't know how to check those, no, but I imagine if he saw something tune related he'd let me know.

 

Oh my fucking god.

 

Do you care to elaborate...?

 

Not particularly. Can you edit the tune yourself to look at the settings? Do you have ATR or whatever that you can use to do this?

 

I don't, unfortunately. I have nothing more than the Accessport and the software for that.

 

What's your mod level? Can you safely flash to an OTS tune (don't go WOT) and see if the cruise issue is resolved?

 

BNR S3, FMIC, 3" intake, catless DP, HKS 3" exhaust, HKS BOV, HPFP internals, etc.

I could certainly try an OTS tune just for the heck of it, but I've heard a ton of bad things about them.

 

Yeah well, sometimes it's what you haven't heard that will bite you in the ass the hardest.
If there's an OTS tune for your specific intake, try running that for a quick cruise test (and log it).

 

poor guy

I think I found your problem, sorry.