Strange problem with Throttle Body

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gorjiam
Posts: 12
Joined: Sat Nov 01, 2014 5:32 pm

Strange problem with Throttle Body

Post by gorjiam »

2008 GR STi. Syvecs S6 PnP.
Recently, at random ocassions (usually just after start up), the throttle body will not respond to pedal input. I need to switch the engine off. Wait a few mins to a few hours and then everything will work again.
However, yesterday, suddenly the throttle body does not respond at all no matter what.
Plugging into Scal shows that the pedal positions are OK. But the throttle body is not responding.
There is also an output Error regarding throttle body positioning error.
We have swapped throttle bodies, no response.
We swapped back to original ECU, the throttle body works fine.

Is there a process to "re calibrate" the throttle body? What else could be the problem?
Note: I have tried reprogramming the S6 hoping it'll "recalibrate" the throttle body. No go.

TimH
JT Innovations
Posts: 621
Joined: Wed Sep 01, 2010 2:51 pm

Re: Strange problem with Throttle Body

Post by TimH »

Basically, the throttle positioning error will mean that the ECU has requested x% throttle position but the feedback of the resulting position is not within tolerance so it flags an error.

It could be a hardware problem - the DBW interface is in an external black box on the PnP kit, so might be worth taking the lid off and making sure the 5 wires inside are still connected OK.

Or it could be that the throttle position and/or pedal position sensor calibration might have been borderline (hence it previously being intermittent). Ryan has done quite a good video on YouTube showing how to calibrate it all:

https://www.youtube.com/watch?v=gUHThP2A09k

gorjiam
Posts: 12
Joined: Sat Nov 01, 2014 5:32 pm

Re: Strange problem with Throttle Body

Post by gorjiam »

I doubt is a cal problem because the car have been running wonderfully on this cal for 2 yrs.
The whole strange issue started about 1 mth ago.
We opened up the small box, no wires are loose, but I thought on my PNP kit it's for CAN BUS?
We also opened up the S6 itself and realised it is all PCB, nothing looks physically broken here.

TimH
JT Innovations
Posts: 621
Joined: Wed Sep 01, 2010 2:51 pm

Re: Strange problem with Throttle Body

Post by TimH »

There are 2 black boxes - one is a CAN bridge (usually connects to the loom adapter via a plug and socket) and the DBW interface which is hard wired in.

Your best bet is to log the DBW-related signals (PPS and TPS) as well as the DBW duty, error and status, and see if you can see where it's going wrong.

I wouldn't totally rule out the CAL. The two TPS sensors need to have been calibrated correctly and must remain within calibrated opening and closing margins otherwise a DBW trip will result. If the calibration was marginal, then deterioration of the wiring could just push them out of tolerance - and temperature may have an effect too. Not likely, but possible.

The logs should reveal why.

gorjiam
Posts: 12
Joined: Sat Nov 01, 2014 5:32 pm

Re: Strange problem with Throttle Body

Post by gorjiam »

Tim,

While cleaning up the car I finally noticed the "black box" you were talking about. I kept fiddling with the one for the CAN.
Opened it up and saw a row of terminal block and as you've guessed, it's loose. Tightened them up and everything is good to go again.
But we'll be logging calibrating the pps and tb just in case.

TimH
JT Innovations
Posts: 621
Joined: Wed Sep 01, 2010 2:51 pm

Re: Strange problem with Throttle Body

Post by TimH »

Glad it was as simple as that :D

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