Buzzing throttle body/strange behavior?
 

Hey guys,

Been trying to diagnose a stumbling-during-acceleration issue on my FR-S for a long time now. Finally got around to looking into the TPS. Questions for you:

1. If car is off, key is ON, does your throttle body emit a loud buzzing sound? Because mine definitely does.

2. If you gradually depress the throttle (car off, key ON), does the throttle plate "jump" open when you've reached like 25% throttle on the pedal? Because mine also does that, and doesn't seem normal to me.

Thanks!

1. Loud is subjective but it buzzes.

2. What do you mean by "open?" Wide open, or does it not begin to open until after quarter throttle? Or does it jump open to about a quarter throttle ignoring the beginning of the arc?

Regarding your second question, I'm not an expert with this platform but it sounds like you're onto something.

Can you borrow someone else's TB and accelerator to swap out? (one at a time)

If I sit and watch the throttle plate as someone in the driver seat slowly depresses the pedal, the plate starts to gradually open, then shoots open to full when the pedal is like 20% depressed. Then after that, pushing the pedal the rest of the way to the floor has zero effect. Plate stays fully open.

That's definitely not good. Here's a clip of how it should work. A friend who actually is an expert shot this clip. It's an S2000 TB but you'll get the idea.

So I feel it may be appropriate to mention that I'm turbo'd running Delicious's tune. I'm assuming the tune shouldn't mess with that, and my stumbling issue occurs on a completely different tune from Dynosty as well, but I just want to be sure before I go further with this theory.

Good to mention but as you also confirmed, it's not the tune. I'm guessing you have an ECUTek system. That will help diagnose the issue but I'm not an expert with it. I log using a Tactrix device.

(edit: well, dipped my toe into logging. really a noob)

Do you have a copy of the service manual, wiring diagram?

I do not. I do however have a multimeter. I noticed that the throttle body connector has 5 pins. I'm assuming 3 of them are for the TPS and the other 2 are for the drive by wire system? Problem is I don't know which are which to test things. Nor do I know what exactly to test since it seems like it might be the drive by wire system that's acting up instead of the TPS. New territory for me.

Grab the electrical manual from here. Start at page 98. You will find the throttle body on page 107 and the accelerator control on 108.

Not sure what to do with that info just yet. It might not be the right place to start.

edit: Due diligence - am I correct in assuming it's not throwing any codes?

This sounds normal to me.
Throttle body actuator make buzzing humming sound totally normal.

Also accelerator position reliative to throttle butterfly position is no linear its controlled my complex throttle maps in ecu.If your ecutek turbo tuned then you could also be running hybrid speed density tune.

The was some recient update to ecutek racerom to combat hesitations in cold weather on speed density tunes.

you need to talk to your tuner, i dont think you can do much diagnostics without loggong and knowing the tune setup.

Sigh. I already sent logs to my tuner. They were very confused by them and told me it looks like a mechanical issue. I suspected TPS because one of the classic symptoms is shuddering/hesitation during acceleration, which is exactly what I'm seeing. Also I'm running the very latest tune from them as of last week. I still get random (jarring) hesitations during acceleration and initial shuddering when going WOT.

not sure if this has anything to do with it
http://www.ft86club.com/forums/showp...3&postcount=46


https://www.google.com.au/search?q=s...e:ft86club.com

According to the filename of my tune, I am running RaceRom 8. (It has RR8 in the filename, I'm assuming that's not just for show)

arh well might indeed by another problem :iono:

Do you have any friends which might let you borrow their TB for testing?